class 10 science chapter 9 case study questions

Case Study Questions Class 10 Science Chapter 9 Heredity and Evolution

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Case study Questions Class 10 Science Chapter 9 are very important to solve for your exam. Class 10 Science Chapter 9 Case Study Questions have been prepared for the latest exam pattern. You can check your knowledge by solving case study-based questions for Class 10 Science Chapter 9 Heredity and Evolution

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In CBSE Class 10 Science Paper, Students will have to answer some questions based on Assertion and Reason . There will be a few questions based on case studies and passage-based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.

Heredity and Evolution Case Study Questions With Answers

Here, we have provided case-based/passage-based questions for Class 10 Science Chapter 9 Heredity and Evolution

Case Study/Passage Based Questions

Question 1:

Pea plants can have smooth seeds or wrinkled seeds. One of the phenotypes is completely dominant over the other. A farmer decides to pollinate one flower of a plant with smooth seeds using pollen from plant with wrinkled seeds. The resulting pea pod has all smooth seeds.

(i) Which of the following conclusions can be drawn? (1) The allele for smooth seeds is dominated over that of wrinkled seeds. (2) The plant with smooth seeds is heterozygous. (3) The plant with wrinkled seeds is homozygous. (a) 1 only (b) 1 and 2 only (c) 1 and 3 only (d) 1, 2 and 3

Answer: (c) 1 and 3 only

(ii) Which of the following crosses will give smooth and wrinkled seeds in same proportion? (a) RR X rr (b) Rr x rr (C) RRX Rr (d) rrrr

Answer: (b) Rr x rr

(iii) Which of the following cross can be used to determine the genotype of a plant with dominant phenotype? (a) RR RR (b) Rr x Rr (c) Rr RR (d) RR x rr

Answer: (d) RR x rr

(iv) On crossing of two heterozygous smooth seeded plants (Rr), a total of 1000 plants were obtained in F 1 generation. What will be the respective number of smooth and wrinkled seeds obtained in F 1 generation? (a) 750, 250 (b) 500, 500 (C) 800, 200 (d) 950, 50

Answer: (a) 750, 250

(v) The characters which appear in the first filial generation are called (a) recessive characters (b) dominant characters (c) lethal characters (d) non-mendelian characters.

Answer: (b) dominant characters

Question 2:

Seema crossed pure breed pea plants having round-yellow seeds with wrinkled green seeds and found that only A-B type of seeds was produced in the F1 generation. When F1 generation pea plants having A-B type of seeds were cross-breed by self-pollination, then in addition to the original round yellow and wrinkled green seeds, two new varieties A-D and C-B types of seeds were also obtained.

2.1) What are the A-B type of seeds? (a) Round -yellow (b) Round- green (c) Wrinkled- yellow (d) Wrinkled- green

Answer(a) Round -yellow

2.2) A-D are __________ and C-B are _______ type of seeds. (a) Round green and wrinkled yellow respectively (b) Wrinkled green and round yellow respectively (c) Round yellow and wrinkled green respectively (d) Wrinkled green and round green respectively

Answer(a) Round green and wrinkled yellow respectively

2.3) A and B are _____________ traits. (a) recessive (b) dominant (c) both (a) and (b) (d) None of these

Answer(b) dominant

2.4) Which one of these will be produced in maximum number in the F2 generation? (a) A-D (b) A-B (c) both (a) and (b) (d) None of these

Answer(b) A-B

2.5) The above cross is known as : (a) Test cross (b) Monohybrid cross (c) Back cross (d) Dihybrid cross

Answer(d) Dihybrid cross

Case Study 4

Purebred pea plant with smooth seeds (dominated characteristic) were crossed with a purebred pea plants with wrinkled seeds (recessive characteristic). The F1 generation was self-pollinated to give rise to the F, generation.

4.1) What is the expected observation of the F1 generation of plants? (a) 1/2 of them have smooth seeds and 1/2 of them have wrinkled seeds. (b) 1/4 of them have wrinkled seeds and 3/4 of them have smooth seeds. (c) 3/4 of them have wrinkled seeds and 1/4 of them have smooth seeds. (d) All of them have smooth seeds.

Answer(d) All of them have smooth seeds.

4.2) What is the expected observation of the F2 generation plants ? (a) 1/2 of them have smooth seeds and 1/2 of them have wrinkled seeds. (b) 1/4 of them have wrinkled seeds and 3/4 of them have smooth seeds. (c) 3/4 of them have wrinkled seeds and 1/4 of them have smooth seeds. (d) All of them have smooth seeds.

Answer(b) 1/4 of them have wrinkled seeds and 3/4 of them have smooth seeds.

4.3) If a genotype consists of different types of alleles, it is called : (a) homozygous (b) heterogyzous (c) monoallelic (d) uniallelic

Answer(b) heterogyzous

4.4) The alternative form of gene is called : (a) dominant character (b) recessive character (c) alternative genes (d) allele

Answer(d) allele

4.5) Which of the following will be the genotypic ratio of the given F2 generation? (a) 1:3 (b) 3:1 (c) 1:2:1 (d) 1:1:1

Answer(c) 1:2:1

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Case Study Chapter 9 Heredity And Evolution

Please refer to Chapter 9 Heredity And Evolution Case Study Questions with answers provided below. We have provided Case Study Questions for Class 10 Science for all chapters as per CBSE, NCERT and KVS examination guidelines. These case based questions are expected to come in your exams this year. Please practise these case study based Class 10 Science Questions and answers to get more marks in examinations.

Case Study Questions Chapter 9 Heredity And Evolution

Case/Passage – 1

Question: A person first crossed pure-breed pea plants having roundyellow seeds with pure-breed pea plants having wrinkledgreen seeds and found that only A-B type of seeds were produced in the F1 generation. When F1 generation pea plants having A-B type of seeds were cross-breed by selfpollination, then in addition to the original round-yellow and wrinkled-green seeds, two new varieties A-D and C-B type of seeds were also obtained. (a) What are A-B type of seeds? (b) State whether A and B are dominant traits or recessive traits. (c) What are A-D type of seeds? (d) What are C-B type of seeds? (e) Out of A-B and A-D types of seeds, which one will be produced in (i) minimum numbers, and (ii) maximum numbers, in the F 2 generation?

(a) Round yellow (b) A (round) and B (yellow) are dominant traits (c) Round-green (d) Wrinkled-yellow (e) (i) A–D (ii) A–B

Question: Question number (a) – (d) are based on the images (A) and (B) given below. Study them and answer the following questions.

class 10 science chapter 9 case study questions

(a) What term can be used for the structure given in image A? (b) What term can be used for the structure given in image B? (c) Which image shows a common ancestry? (d) Which image has a common function but different origin?

(a) Homologous organs (b) Analogous organs (c) Image A shows common ancestry (d) Image B i.e., analogous organs have a different origin but common functions.

Case/Passage – 2

Most human chromosomes have a maternal and a paternal copy, and we have 22 such pairs. But one pair, called the sex chromosomes, is odd in not always being a perfect pair. Women have a perfect pair of sex chromosomes, both called X. But men have a mismatched pair in which one is a normal-sized X while the other is a short one called Y. So women are XX, while men are XY

Question: If a normal cell of human body contains 46 pairs of chromosomes then the numbers of chromosomes in a sex cell of a human being is most likely to be: (a) 60 (b) 23 (c) 22 (d) 40

Question: The process where characteristics are transmitted from parent to offsprings is called: (a) Variation (b) Heredity (c) Gene (d) Allele (e) None of the above

Question: In human males, all the chromosomes are paired perfectly except one. These unpaired chromosomes are: (a) Large chromosome (b) Small chromosome (c) Y chromosome (d) X chromosome

Question: Which of the following determines the sex of a child? (a) The length of the mother’s pregnancy (b) The length of time between ovulation and copulation (c) The presence of an X chromosome in an ovum (d) The presence of a Y chromosome in a sperm

Question:Who have a perfect pair of sex chromosomes? (a) Girls only (b) Boys only (c) Both girls and boys (d) It depends on many other factors

Case/Passage – 3

In some animals, the temperature at which fertilised eggs are kept determines whether the animal developing in the egg will be male or female. In other animals, such as snails, individuals can change sex, that is sex is not genetically determined. In human beings, sex of individuals is largely genetically determined. All chromosomes in human beings are not paired. We have 22 pairs and one pair of sex chromosomes which is odd and not always a perfect pair.

Question. Who is responsible for birth of male child? (a) Father (b) Mother (c) Father only in first pregnancy. (d) Mother only in first pregnancy

Question. How many pairs of chromosomes are called autosomes? (a) 23 (b) 22 (c) 21 (d) 20

Question. Which pair of chromosomes are present in Male (a) XX (b) YY (c) XY (d) XXY

Question. Which of the following statement is true? (a) Men have short sized X chromosome (b) Men have one long sized Y chromosome (c) Men have normal sized Y chromosome (d) Men have one short sized Y chromosome

Question. Which pair of chromosomes are present in female? (a) XX (b) YY (c) XY (d) XXY

Case Study Chapter 9 Heredity And Evolution

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CBSE Class 10

CBSE Class 10 Science Chapter Wise Important Case Study Questions

Chapter wise important case study questions cbse class 10 science: cbse class 10 science board exam 2024 is just around the corner and students are working hard to score maximum marks. check these case study questions from class 10 science to ace your examination this year also download the solutions from the pdf attached towards the end. .

CBSE Class 10 Science Chapter Wise Important Case Study Questions: While the CBSE Board exam for Class 10 students are ongoing, the CBSE Class 10 Science board exam 2024 is to be held on March 2, 2024. With the exams just a few days away, CBSE Class 10th Board exam candidates are rushing to prepare the remaining syllabus, practising their weak portions, trying to revise the important questions from the past year papers, practise questions, etc.

Why are CBSE Class 10 Science Case Study Questions Important?

Section A : 20 Multiple Choice Questions (MCQs) carrying 1 mark each.
Section B : 6 Very Short Answer type questions carrying 2 marks each. Answers to these questions should be in the range of 30 to 50 words.
Section C : 7 Short Answer type questions carrying 3 marks each. Answers to these questions should be in the range of 50 to 80 words.
Section D : 3 Long Answer type questions carrying 5 marks each. Answers to these questions should be in the range of 80 to 120 words.
Section E : 3 Case Based/ Source Based units of assessment (4 marks each) with sub-parts.

How to solve case study questions in CBSE Class 10 Science?

Read the case given and the associated questions carefully.
Read the questions attentively and analyse what they are asking.
Apply your subject knowledge and theories in the given case to decide what the correct answers should be.

1.A chemical reaction is a representation of chemical change in terms of symbols and formulae of reactants and products. There are various types of chemical reactions like combination, decomposition, displacement, double displacement, oxidation and reduction reactions. Reactions in which heat is released along with the formation of products are called exothermic chemical reactions. All combustion reactions are exothermic reactions.

(i) The massive force that pushes the rocket forward through space is generated due to the

(a) combination reaction

(b) decomposition reaction

(d) double displacement reaction

(ii) A white salt on heating decomposes to give brown fumes and yellow residue is left behind. The yellow residue left is of

(a) lead nitrate

(b) nitrogen oxide

(d) oxygen gas

(iii) Which of the following reactions represents a combination reaction?

(a) CaO (s) + H2O (l) → Ca (OH)2 (aq)

(b) CaCO3 (s) → CaO (s) + CO2(g)

(d) 2FeSO4(s) → Fe2O3 (s) +SO2(g) + SO3(g)

(iv) Complete the following statements by choosing correct type of reaction for X and Y.

Statement 1: The heating of lead nitrate is an example of ‘X’ reaction.

Statement 2: The burning of magnesium is an example of ‘Y’ reaction.

(a)X-Combination,Y-Decomposition

(b)X-Decomposition,Y-Combination

(c)X-Combination,Y-Displacement

(d) X- Displacement, Y-Decomposition

2.The earlier concept of oxidation and reduction is based on the addition or removal of oxygen or hydrogen elements so, in terms of oxygen and hydrogen, oxidation is addition of oxygen to a substance and removal of hydrogen from a substance. On the other hand, reduction is addition of hydrogen to a substance and removal of oxygen from a substance. The substance which gives oxygen to another substance or removes hydrogen from another substance in an oxidation reaction is known as oxidising agent, while the substance which gives hydrogen to another substance or removes oxygen from another substance in a reduction reaction is known as reducing agent. For example,

(i) A redox reaction is one in which

(a) both the substances are reduced

(b) both the substances are oxidised

(d) one substance is oxidised while the other is reduced.

(ii) In the reaction, H2S+Cl2⟶S+2HCl

(a) H2S is the reducing agent.

(b) HCl is the oxidising agent.

(d) Cl2 is the reducing agent.

(iii) Which of the following processes does not involve either oxidation or reduction?

(a) Formation of slaked lime from quicklime.

(b) Heating mercuric oxide.

(d) Formation of zinc from zinc blende.

(iv) Mg+CuO⟶MgO+Cu

Which of the following is wrong relating to the above reaction?

(a) CuO gets reduced

(b) Mg gets oxidised.

(d) It is a redox reaction.

3.A copper vessel gets tarnished due to formation of an oxide layer on its surface. On rubbing lemon on the vessel, the surface is cleaned, and the vessel begins to shine again. This is due to the fact that which reacts with the acid present in lemon to form a salt which is washed away with water. As a result, the layer of copper oxide is removed from the surface of the vessel and the shining surface is exposed.

1.Which of the following acids is present in lemon?

(a) Formic acid

(b) Acetic acid

(d) Hydrochloric acid

2.The nature of copper oxide is

d) amphoteric

3.Name the salt formed in the above reaction

a) copper carbonate

b) copper chloride

c)copper citrate

d) copper citrate

4.The phenomenon of copper getting tarnished is

a) corrosion

b) rancidity

c) displacement

d)none of these

4.Metals as we know, are very useful in all fields, industries in particular. Non-metals are no less in any way. Oxygen present in air is essential for breathing as well as for combustion. Non-metals form a large number of compounds which are extremely useful, e.g., ammonia, nitric acid, sulphuric acid, etc. Non-metals are found to exist in three states of matter. Only solid non-metals are expected to be hard however, they have low density and are brittle. They usually have low melting and boiling points and are poor conductors of electricity.

i.____________ is a non-metal but is lustrous

A.Phosphorus

ii.Which of the following is known as 'King of chemicals'?

C. Sulphuric acid

D. Nitric acid

iii.Which of the following non-metals is a liquid?

iv.Hydrogen is used

A.for the synthesis of ammonia

B. for the synthesis of methyl alcohol

C.nitrogenous fertilizers

D. all of these

5.Nisha observed that the bottoms of cooking utensils were turning black in colour while the flame of her stove was yellow in colour. Her daughter suggested cleaning the air holes of the stove to get a clean, blue flame. She also told her mother that this would prevent the fuel from getting wasted.

a) Identify the reasons behind the sooty flame arising from the stove.

b) Can you distinguish between saturated and unsaturated compounds by burning them? Justify your answer.

c) Why do you think the colour of the flame turns blue once the air holes of the stove are cleaned?

6.Blood transport food, Oxygen and waste materials in our bodies. It consists of plasma as a fluid medium. A pumping organ [heart] is required to push the blood around the body. The blood flows through the chambers of the heart in a specific manner and direction. While flowing throughout the body, blood exerts a pressure against the wall or a vessel.

Pulmonary artery
Pulmonary vein
Very narrow and have high resistance
Much wide and have low resistance
Very narrow and have low resistance
Much wide and have high resistance
It is a hollow muscular organ
It is four chambered having three auricles and one ventricle.
It has different chambers to prevent O2 rich blood from mixing with the blood containing CO2
Both A & C
Blood = Plasma + RBC + WBC + Platelets
Plasma = Blood – RBC
Lymph = Plasma + RBC
Serum = Plasma + RBC + WBC

7.A brain is displayed at the Allen Institute for Brain Science. The human brain is a 3-pound (1.4-kilogram) mass of jelly-like fats and tissues—yet it's the most complex of all known living structures The human brain is more complex than any other known structure in the universe. Weighing in at three pounds, on average, this spongy mass of fat and protein is made up of two overarching types of cells—called glia and neurons— and it contains many billions of each. Neurons are notable for their branch-like projections called axons and dendrites, which gather and transmit electrochemical signals. Different types of glial cells provide physical protection to neurons and help keep them, and the brain, healthy. Together, this complex network of cells gives rise to every aspect of our shared humanity. We could not breathe, play, love, or remember without the brain.

1)Animals such as elephants, dolphins, and whales actually have larger brains, but humans have the most developed cerebrum. It's packed to capacity inside our skulls and is highly folded. Why our brain is highly folded?

b) Learning

3)Which among these protects our brain?

a)Neurotransmitter

b) Cerebrospinal fluid

d) Grey matter

4.Ram was studying in his room. Suddenly he smells something burning and sees smoke in the room. He rushes out of the room immediately. Was Ram’s action voluntary or involuntary? Why?

8.Preeti is very fond of gardening. She has different flowering plants in her garden. One day a few naughty children entered her garden and plucked many leaves of Bryophyllum plant and threw them here and there in the garden. After few days, Preeti observed that new Bryophyllum plants were coming out from the leaves which fell on the ground.

1.What does the incident sited in the paragraph indicate?

(a). Bryophyllum leaves have special buds that germinate to give rise to new plant.

(b). Bryophyllum can propagate vegetatively through leaves.

(c). Bryophyllum is a flowering plant that reproduces only asexually

(d). Both (a) and (b).

2.Which of the following plants can propagate vegetatively through leaves like Bryophyllum?

3.Do you think any other vegetative part of Bryophyllum can help in propagation? If yes, then which part?

4.Which of the following plant is artificially propagated (vegetatively) by stem cuttings in horticultural practices?

(b)Snakeplant

(d)Water hyacinth

9.The growing size of the human population is a cause of concern for all people. The rate of birth and death in a given population will determine its size. Reproduction is the process by which organisms increase their population. The process of sexual maturation for reproduction is gradual and takes place while general body growth is still going on. Some degree of sexual maturation does not necessarily mean that the mind or body is ready for sexual acts or for having and bringing up children. Various contraceptive devices are being used by human beings to control the size of the population.

1) What are common signs of sexual maturation in boys?

a) Broadening of shoulders

b) Development of mammary glands

c) Broadening of waist

d) High pitch of voice

2) Common sign of sexual maturation in girls is

a) Low pitch voice

b) Appearance of moustache and beard

c) Development of mammary glands

d) Broadening of shoulders

3) Which contraceptive method changes the hormonal balance of the body?

b) Diaphragms

c) Oral pills

d) Both a) and b)

4) What should be maintained for healthy society?

a) Rate of birth and death rate

b) Male and female sex ratio

c) Child sex ratio

d) None of these

10.Pea plants can have smooth seeds or wrinkled seeds. One of the phenotypes is completely dominant over the other. A farmer decides to pollinate one flower of a plant with smooth seeds using pollen from a plant with wrinkled seeds. The resulting pea pod has all smooth seeds.

i) Which of the following conclusions can be drawn?

(1) The allele for smooth seeds is dominated over that of wrinkled seeds.

(2) The plant with smooth seeds is heterozygous.

(3) The plant with wrinkled seeds is homozygous.

(b) 1 and 2 only

(d) 1, 2 and 3

ii) Which of the following crosses will give smooth and wrinkled seeds in same proportion?

(a) RR X rr

(b) Rr X rr

(d) rr X rr

iii) Which of the following cross can be used to determine the genotype of a plant with dominant phenotype?

(a) RR X RR

(b) Rr X Rr

(d) RR X rr

iv) On crossing of two heterozygous smooth seeded plants (Rr), a total of 1000 plants were obtained in F1 generation. What will be the respective number of smooth and wrinkled seeds obtained in F1 generation?

(a) 750, 250

(b) 500, 500

(d) 950, 50

11.Food chains are very important for the survival of most species.When only one element is removed from the food chain it can result in extinction of a species in some cases.The foundation of the food chain consists of primary producers.Primary producers or autotrophs,can use either solar energy or chemical energy to create complex organic compounds,whereas species at higher trophic levels cannot and so must consume producers or other life that itself consumes producers. Because the sun’s light is necessary for photosynthesis,most life could not exist if the sun disappeared.Even so,it has recently been discovered that there are some forms of life,chemotrophs,that appear to gain all their metabolic energy from chemosynthesis driven by hydrothermal vents,thus showing that some life may not require solar energy to thrive.

1.If 10,000 J solar energy falls on green plants in a terrestrial ecosystem,what percentage of solar energy will be converted into food energy?

(d)It will depend on the type of the terrestrial plant

2.Matter and energy are two fundamental inputs of an ecosystem. Movement of

(a)Energy is by directional and matter is repeatedly circulating

(b)Energy is repeatedly circulating and matter is unidirectional

(c)Energy is unidirectional and matter is repeatedly circulating

(d)Energy is multidirectional and matter is bidirectional

3.Raj is eating curd/yoghurt. For this food intake in a food chain he should be considered as occupying

(a)First trophic level

(b)Second trophic level

(c)Third trophic level

(d)Fourth trophic level

4.Which of the following, limits the number of trophic levels in a food chain

(a)Decrease in energy at higher trophic levels

(b)Less availability of food

(c)Polluted air

5.The decomposers are not included in the food chain. The correct reason for the same is because decomposers

(a) Act at every trophic level at the food chain

(b) Do not breakdown organic compounds

(d) Release enzymes outside their body to convert organic material to inorganic forms

12.Shyam participated in a group discussion in his inter school competition on the practical application of light and was very happy to win an award for his school. That very evening his father gave treat to celebrate Shyam’s win. Shyam while sitting saw an image of a person sitting at his backside in his curved plate and could see that person’s mobile drop in the flower bed. Person was not aware until Shyam went and informed him. He thanked Shyam for his clever move.

a)From which side of his plate Shyam observed the incident –

i)outward curved

ii)inward curved

iii)plane surface

b)Part of plate from which Shyam observed the incident acted like a-

i)concave mirror

ii)convex mirror

iii)plane mirror

c)The nature of the size of the image formed in above situation is –

i)real, inverted and magnified

ii)same size , laterally inverted

iii)virtual, erect and diminished

iv)real , inverted and diminished

d)Magnification of the image formed by convex mirror is –

more than 1

iii)equal to 1

iv)less than 1

The location of image formed by a convex lens when the object is placed at infinity is

(a) at focus

When the object is placed at the focus of concave lens, the image formed is

(a)real and smaller

(b) virtual and smaller

The size of image formed by a convex lens when the object is placed at the focus ofconvex lens is

(a) highly magnified

(b) point in size

When the object is placed at 2F in front of convex lens, the location of image is

(b) between F and optical center

(d) none of the above

14.One of the wires in domestic circuits supply, usually with a red insulation cover, is called live wire. with black insulation is called neutral wire. The earth wire, which has insulation of green colour, is usually connected to a metal plate deep in the earth near the house appliances that has a metallic body. Overloading contact, in such a situation the current in the circuit abruptly increases. circuit prevents damage to the appliances and the circuit due to overloading.

1 When do we say that an electrical appliance

2 Mention the function of earth wire in electrical line

3 How is an electric fuse connected in a domestic circuit?

4 When overloading and short circuiting are said to occur?

5 What is a live wire?

15.Light of all the colours travel at the same speed in vacuum for all wavelengths. But in any transparent medium(glass or water), the light of different colours travels at different speeds for different wavelengths, which means that the refractive index of a particular medium is different for different wavelengths. As there is a difference in their speeds, the light of different colours bend through different angles. The speed of violet colour is maximum and the speed of red colour is minimum in glass so, the red light deviates least and violet colour deviates most. Hence, higher the wavelength of a colour of light, smaller the refractive index and less is the bending of light.

(i)Which of the following statements is correct regarding the propagation of Light of different colours of white light in air?

(a) Red light moves fastest.

(b) Blue light moves faster than green light.

(d) Yellow light moves with the mean speed as that of the red and the violet light.

(ii)Which of the following is the correct order of wavelength?

(a) Red> Green> Yellow

(b) Red> Violet> Green

(d) Red> Yellow> Orange

(iii)Which of the following is the correct order of speed of light in glass?

(a) Red> Green> Blue

(b) Blue> Green> Red

(d) Green> Red> Blue

(iv)Which colour has maximum frequency?

16.The region around a magnet where magnetism acts is represented by the magnetic field.The force of magnetism is due to moving charge or some magnetic material. Like stationary charges produce an electric field proportional to the magnitude of charge, moving charges produce magnetic fields proportional to the current. In other words, a current carrying conductor produces a magnetic field around it. The subatomic particles in the conductor, like the electrons moving in atomic orbitals, are responsible for the production of magnetic fields. The magnetic field lines around a straight conductor (straight wire) carrying current are concentric circles whose centres lie on the wire.

1)The magnetic field associated with a current carrying straight conductor is in anti- clockwise direction. If the conductor was held horizontally along east west direction,what is the direction of current through it?

2)Name and state the rule applied to determine the direction of magnetic field in a straight current carrying conductor.

3)Ramus performs an experiment to study the magnetic effect of current around a current carrying straight conductor with the help of a magnetic compass. He reports that

a)The degree of deflection of magnetic compass increases when the compass is moved away from the conductor.

b)The degree of deflection of the magnetic compass increases when the current through the conductor is increased.

Which of the above observations of the student appears to be wrong and why?

Case Study Questions Class 10 Science CBSE Chapter Wise PDF

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CBSE Class 10 Science Case Study Questions Download Free PDF

If you are looking for the CBSE Class 10 Science Case Study Questions in PDF, then you are in the right place. CBSE 10th Class Case Study for the Science Subject is available here. These Case studies can help the students to solve the different types of questions that are based on the case study.

CBSE Board will be asking case study questions based on Science subjects in the upcoming board exams. Thus, it becomes an essential resource to study.

The Science Subject case study for class 10th covers a wide range of chapters from the Science. Students willing to score good marks in their board exams can use it. The questions are highly interactive and it allows students to use their thoughts and skills to solve such kinds of questions.

Case Study Questions Class 10 Science

In board exams, students will find the questions based on assertion and reasoning . Also, there will be a few questions based on case studies. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.

Case Study Questions for Chapter 1 Chemical Reactions and Equations
Case Study Questions for Chapter 2 Acids, Bases, and Salts
Case Study Questions for Chapter 3 Metals and Non-Metals
Case Study Questions for Chapter 4 Carbon and Its Compounds
Case Study Questions for Chapter 5 Periodic Classification of elements
Case Study Questions for Chapter 6 Life Processes
Case Study Questions for Chapter 7 Control and Coordination
Case Study Questions for Chapter 8 How do organisms reproduce?
Case Study Questions for Chapter 9 Heredity and Evolution
Case Study Questions for Chapter 10 Light reflection and refraction
Case Study Questions for Chapter 11 Human eye and colorful world
Case Study Questions for Chapter 12 Electricity
Case Study Questions for Chapter 13 Magnetic effects of current
Case Study Questions for Chapter 15 Our Environment

The above Case studies for CBSE Class 10 Science will help you to score good marks in the Case Study questions that have been coming in your examinations. These CBSE Class 10 Science Case Study have been developed by experts of cbseexperts.com for benefit of Class 10 students.

Class 10 Science Assertion and Reason Questions

Case Study Type Questions in Science Class 10

Case Study Type Questions in Science Class 10 include the information or data. Students willing to solve them are required to read the passage carefully and then solve them. While solving the paragraph the ideal way is to highlight the key information or given data.

Because later it will ease them to write the final answers. Science Case study type questions consist of 4 to 5 questions that should be answered in an MCQ manner.

While reading the paragraph students will get the clue in between about the possible answer of the question. They should definitely highlight those questions. This is the best way to solve such kind of Case study Type Questions.

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Case Study Questions Class...

Case Study Questions Class 10 Science

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Download the app to get CBSE Sample Papers 2023-24, NCERT Solutions (Revised), Most Important Questions, Previous Year Question Bank, Mock Tests, and Detailed Notes.

Download Case study questions for CBSE class 10 Science in PDF format from the myCBSEguide App . We have the new pattern case study-based questions for free download. Class 10 Science case study questions

This article will guide you through:

What are case study questions?

Sample Papers with Case Study questions
Class 10 Science Case Study question examples
How to get case-based questions for free?
How to attempt the case-based questions in Science?

Questions based on case studies are some real-life examples. The questions are asked based on a given paragraph i.e. Case Study. Usually, 4-5 questions are asked on the basis of the given passage. In most cases, these are either MCQs or assertion & reason type questions. Let’s take an example to understand. There is one paragraph on how nitrogen is generated in the atmosphere. On the basis of this paragraph, the board asks a few objective-type questions. In other words, it is very similar to the unseen passages given in language papers. But the real cases may be different. So, read this article till the end to understand it thoroughly.

What is CBE?

CBSE stands for competency-based education. The case study questions are part of this CBE. The purpose of CBE is to demonstrate the learning outcomes and attain proficiency in particular competencies.

Questions on Real-life Situations

As discussed the case study questions are based on real-life situations. Especially for grade 10 science, it is very essential to have the practical knowledge to solve such questions. Here on the myCBSEguide app, we have given many such case study paragraphs that are directly related to real-life implications of the knowledge.

Sample Papers with Case Study Questions

Class 10 Science Sample Papers with case study questions are available in the myCBSEguide App . There are 4 such questions (Q.No.17 to 20) in the CBSE model question paper. If you analyze the format, you will find that the MCQs are very easy to answer. So, we suggest you, read the given paragraph carefully and then start answering the questions. In some cases, you will find that the question is not asked directly from the passage but is based on the concept that is discussed there. That’s why it is very much important to understand the background of the case study paragraph.

CBSE Case Study Sample Papers

You can download CBSE case study sample papers from the myCBSEguide App or Student Dashboard. Here is the direct link to access it.

Case Study Question Bank

As we mentioned that case study questions are coming in your exams for the last few years. You can get them in all previous year question papers issued by CBSE for class 1o Science. Here is the direct link to get them too.

Class 10 Science Case Study Question Examples

As you have already gone through the four questions provided in the CBSE model question paper , we are proving you with other examples of the case-based questions in the CBSE class 10 Science. If you wish to get similar questions, you can download the myCBSEguide App and access the Sample question papers with case study-type questions.

Case-based Question -1

Read the following and answer any four questions: Salt of a strong acid and strong base is neutral with a pH value of 7. NaCl common salt is formed by a combination of hydrochloride and sodium hydroxide solution. This is the salt that is used in food. Some salt is called rock salt bed of rack salt was formed when seas of bygone ages dried up. The common salt thus obtained is an important raw material for various materials of daily use, such as sodium hydroxide, baking soda, washing soda, and bleaching powder.

Phosphoric acid
Carbonic acid
Hydrochloric acid
Sulphuric acid
Blue vitriol
Washing soda
Baking soda
Bleaching powder

Case-based Question -2

V 1 + V 2 + V 3
V 1 – V 2 +V 2
None of these
same at every point of the circuit
different at every point of the circuit
can not be determined
20 3 Ω 203Ω
15 2 Ω 152Ω

Case-based Question -3

pure strips
impure copper
refined copper
none of these
insoluble impurities
soluble impurities
impure metal
bottom of cathode
bottom of anode

How to Attempt the Case-Based Questions in Science?

Before answering this question, let’s read the text given in question number 17 of the CBSE Model Question Paper.

All living cells require energy for various activities. This energy is available by the breakdown of simple carbohydrates either using oxygen or without using oxygen.

See, there are only two sentences and CBSE is asking you 5 questions based on these two sentences. Now let’s check the first questions given there.

Energy in the case of higher plants and animals is obtained by a) Breathing b) Tissue respiration c) Organ respiration d) Digestion of food

Now let us know if you can relate the question to the paragraph directly. The two sentences are about energy and how it is obtained. But neither the question nor the options have any similar text in the paragraph.

So the conclusion is, in most cases, you will not get direct answers from the passage. You will get only an idea about the concept. If you know it, you can answer it but reading the paragraph even 100 times is not going to help you.

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Class 10 Science Chapter 9 Case Based Questions - Light Reflection and Refraction

$Class 10 Science Chapter 9 Case Based Questions - Light Reflection and Refraction$

Correct Answer is Option (b) In rectangular glass slab the ray undergoes only refraction and emerges out parallel. In a prism the emerging ray is not parallel but split due to change in wavelength of different colour of light. The shape of the glass slab with two prisms up and down splits light but recombines it into one.

Question 2: The light changes its path as its medium changes. Which of the following is incorrect statement. (a) Speed of light is different in different media. (b) Light changes its path because light only travels in straight line. (c) Speed of light is dependent on medium through which it is passing. (d) The light chooses the path with minimum time, as it changes its medium.

Correct Answer is Option (b) Light changes its path because light only travels in straight line.

Question 3: Light travel fastest in: (a) Air (b) Vacuum (c) Glass (d) diamond

Correct Answer is Option (b) Light travels faster in vacuum than any other medium. This is because there is no obstruction in vacuum for the propagation of light and thus, the refractive index of vacuum is the lowest.

An object is kept at a distance of 18 cm, 20 cm, 22 cm and 30 cm, from a lens of power + 5D. Question 4: The focal length of the given lens is: (a) 0.2 cm (b) 20 cm (c) 5cm (d) 0.5 cm

Correct Answer is Option (b) P = 1/f, f = 100/5 = 20 cm

Question 5: In which case or cases would you get a magnified image? (a) 18cm (b) 20cm (c) 22cm (d) All the above

Correct Answer is Option (d) An object at 18 cm, 22 cm, and 30 cm, the image can be magnified.

Question 6: The power of a lens of focal length 1 metre is called as: (a) Refractive index (b) 1 dioptre (c) Speed of light (d) Wavelength

Correct Answer is Option (b) The power of a lens whose focal length is one metre is dioptre .

Question 7: Name the lens/mirror used in film projectors and telescopes: (a) Convex lens (b) Concave lens (c) Convex mirror (d) Concave mirror

Correct Answer is Option (a) Convex lens used in film projectors and telescopes, where the distance between the eye's lens and retina is too short, as a result of which the focal point lies behind the retina. Eyeglasses with convex lenses increase refraction, and accordingly reduce the focal length.

Question 8: Which of the magnified image can we get on a screen? (a) At 18 cm (b) At 18 cm and 22 cm (c) At 20 cm and 22 cm (d) At 22 and 30 cm

Correct Answer is Option (d) At 22 cm and 30 cm, image can be obtained on a screen.

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Case Based Type Practice Questions: Light- Reflection & Refraction Free PDF Download

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NCERT Solutions
NCERT Solutions for Class 10
NCERT Class 10 Science
Chapter 9 Heredity And Evolution

NCERT Solutions for Class 10 Science Chapter 9 Heredity and Evolution

Ncert solutions class 10 science heredity and evolution – cbse free pdf download.

* According to the CBSE Syllabus 2023-24, this chapter has been renumbered as Chapter 8.

NCERT Solutions for Class 10 Science Chapter 9 Heredity and Evolution provides the answers to all the textbook questions with a thorough analysis of the concept. Discover important concepts and the method of giving their solutions with the NCERT Solutions given here, which are carefully answered by our highly qualified teachers. Intext questions are also answered with adequate explanations, wherever necessary. Furthermore, we make sure that relevant content on NCERT Solutions Class 10 is regularly updated as per the CBSE Board. We also ensure that the answers that we deliver are tailored to meet various criteria that teachers look for when awarding marks.

Download Exclusively Curated Chapter Notes for Class 10 Science Chapter – 9 Heredity and Evolution

Download most important questions for class 10 science chapter – 9 heredity and evolution.

Chapter 9 of NCERT Solutions is a very crucial and scoring chapter, as many questions would appear in the CBSE Board exams. Students will obtain an in-depth knowledge of the concepts as per the latest syllabus of the CBSE Board. To help students with exercise-wise answers, BYJU’S allows the free download of PDF solutions, which can be accessed without any time constraints. It also speeds up the revision of the chapters a few days before the exam. Students can download the free PDF of NCERT Solutions for Class 10 Science from the links given here.

Chapter 1 Chemical Reactions and Equations
Chapter 2 Acids, Bases and Salts
Chapter 3 Metals and Non-metals
Chapter 4 Carbon and Its Compounds
Chapter 5 Periodic Classification of Elements
Chapter 6 Life Processes
Chapter 7 Control and Coordination
Chapter 8 How Do Organisms Reproduce?
Chapter 10 Light Reflection and Refraction
Chapter 11 The Human Eye and Colourful World
Chapter 12 Electricity
Chapter 13 Magnetic Effects of Electric Current
Chapter 14 Sources of Energy
Chapter 15 Our Environment
Chapter 16 Management of Natural Resources

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NCERT Solutions for Class 10 Science Chapters

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Access Answers to Science NCERT Solutions for Class 10 Chapter 9 Heredity and Evolution

Exercise-9.1 Page: 143

1. If a trait A exists in 10% of a population of an asexually reproducing species and trait B exists in 60% of the same population, which trait is likely to have arisen earlier?

Trait B is more probable to arise early as this trait has already been existing and replicating in a larger percentage of the population as compared to trait A.

2. How does the creation of variations in a species promote survival?

Genetic variations enable the species to better adapt to changes in its environment. Moreover, it is an important force in evolution as it allows the frequency of alleles to increase or decrease through natural selection. These variations will determine the difference between extinction or continuation of the species.

Exercise-9.2 Page: 147

1. How do Mendel’s experiments show that traits may be dominant or recessive?

Mendel showed that the traits could either be dominant or recessive through his experiments that focused on the mono-hybrid cross. The experiment involved him crossing tall (TT) pea plants with dwarf (tt) pea plants. The resultant plants which formed after fertilisation represented the F1 (or filial) generation. All the F1 plants were tall. Mendel then proceeded to self-pollinate the filial generation plants, and the result was that 1/4th of the plants obtained in the F2 generation were dwarfs. From this experiment, Mendel concluded that the F1 tall plants were not true-breeding; instead, they carried the traits for both tall and dwarf heights. A portion of the plants was tall due to the fact that the traits for tallness were dominant over the traits for dwarfness. This cements the notion that traits can either be dominant or recessive.

2. How do Mendel’s experiments show that traits are inherited independently?

Mendel’s experiments show that traits are inherited independently through his dihybrid cross experiment. The experiment involved him using two traits – namely, seed shape and seed colour. The colour yellow (YY) is dominant over green (yy), while the round shape (RR) is dominant over the wrinkled shape (rr). The F2 progeny of the dihybrid cross resulted in a phenotypic ratio of 9:3:3:1; therefore, 9 plants with round yellow (RRYY) seeds, 3 plants with round green (RRyy) seeds and 3 plants with wrinkled yellow (rrYY) seeds and one with wrinkled green seeds (rryy). He further observed that the wrinkled greens and the round yellow are parental combinations while the round green and wrinkled yellow are new. A dihybrid cross between two seeds with dominant traits (RRYY) and non-dominant traits (rryy) resulted in the production of 4 types of gametes (RY, Ry, rY and ry). This means each of the gametes segregates independently of the other, and each with a frequency of 25% of the total gametes produced.

3. A man with blood group A marries a woman with blood group O, and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O – is dominant? Why or why not?

Given information is not enough to tell us which characteristics are dominant – blood group A or O. Blood type A is always dominant in ABO blood, and blood type O is always recessive. Here, the father’s blood group may be genotypically AA (homozygous) or AO (heterozygous), whereas that of the mother can be OA or OO.

4. How is the sex of the child determined in human beings?

The sex of the child in humans is determined by the males. Males have XY chromosomes, while females have XX chromosomes. Hence, if:

The male’s X chromosomes combine with the female’s X chromosomes, the mother gives birth to a girl
The male’s Y chromosome combines with the female’s X chromosome, the mother gives birth to a boy

NCERT Solutions for Class 10 Chapter 9 Image 1

Exercise-9.3 Page: 150

1. What are the different ways in which individuals with a particular trait may increase in a population?

An individual attribute could increase a population in the following 2 ways:

(a) Natural selection: If an attribute is useful to a population, it’ll increase naturally.

For example, mosquitoes which are resilient against a particular pesticide will pass on their genes so that future generations become resistant as well. The mosquitoes which are affected by the pesticide die out.

(b) Genetic drift: If a species faces a catastrophic event where most of the population is wiped out, the surviving population can pass on their traits to the following generations. This may result in a rise in the attribute within the population.

2. Why are traits acquired during the lifetime of an individual not inherited?

Traits acquired during a lifetime cannot be inherited by successive generations as the changes do not reflect in the DNA of the germ cells. For instance, a football player cannot pass on his skills to his offspring as they are limited to non-reproductive cells only.

3. Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics?

As the size of the tiger population decreases, the genetic pool of the species decreases too. This results in a limitation on the variations which will be introduced within the genetic makeup of the tigers. This lack of variation will result in serious implications. For example, if an illness spreads within the tiger population, it can potentially wipe out the whole population, possibly causing their extinction.

Exercise – 9.4 Page: 151

1. What factors could lead to the rise of a new species?

Factors that would result in a new species are as follows:

(a) Mutation

(b) Genetic drift

(d) Geographical isolation

(e) Generative isolation for prolonged periods

(f) Environmental factors on the isolated populations

(g) Quantum of genetic variant transmissible from one generation to the following generation

2. Will geographical isolation be a major factor in the speciation of a self-pollinating plant species? Why or why not?

In the pollination of plant species, geographical isolation is usually not a major factor, as no new trait will become part of the genetic makeup of a self-pollinating plant species. However, there are some possibilities of some environmental changes which could result in some variations.

3. Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually? Why or why not?

In the case of asexually reproducing organisms, geographical isolation can’t be considered a factor. This is due to the fact that meiosis does not occur during asexual modes of reproduction.

Exercise – 9.5 Page: 156

1. Give an example of characteristics being used to determine how close two species are in evolutionary terms.

Let us take the instance of humans and chimpanzees. Chimpanzees are able to express a wide range of emotions, such as busting out in laughter or smiling – this trait was once thought to be a feature exclusive to humans. The smile can be linked to the activation of the brain’s limbic system, where the orbicularis oculi muscle involuntarily contracts and raises the cheeks, forming wrinkles around the eyes. This implies that the smile is a true and genuine smile. Interestingly, this type of reflex has a name – the Duchenne smile. Moreover, research has shown that chimpanzees share 98.6% of our DNA – This means that humans and chimpanzees shared a common ancestor aeons ago. It is also important to note that chimpanzees are the closest living relatives to humans.

2. Can the wing of a butterfly and the wing of a bat be considered homologous organs? Why or why not?

The wing of a butterfly and the wing of a bat cannot be considered homologous organs as they do not share a common ancestor. Even though both structures aid in flying, they have evolved separately. To prove this, the wings of a butterfly are composed of two chitinous membranes, whereas the wings of a bat are composed of a bony skeleton, complete with blood vessels. Hence, these aren’t homologous organs but rather analogous organs.

3. What are fossils? What do they tell us about the process of evolution?

Fossils are the preserved remains of animals or plants, or other organisms that died out millions of years ago. These fossils tell us about a lot of extinct animals and also give insights into how evolution might have occurred. Fossils can be used to understand how an organism would have lived and what it may have looked like. More importantly, we can correlate with fossils as well as extant organisms to understand their relationships. For instance, scientists were able to recover protein sequences from a dinosaur called the T-rex, which confirmed its avian lineage. This means birds are the extant relatives of (avian) dinosaurs. Moreover, the pattern of fossil distribution gives us an idea of the time in history when various species were formed or become extinct.

Exercise – 9.6 Page: 158

1. Why are human beings who look so different from each other in terms of size, colour and looks said to belong to the same species?

While human beings do vary in colour and general appearance, their genetic makeup is identical to any other human. One of the speculations put forth for our drastic changes is due to evolutionary pressure, where the need to be easily recognised pushed us towards having widely different faces.

2. In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a ‘better’ body design? Why or why not?

Body designs are the result of environmental needs and pressure. Hence, we can’t conclude that one organism has a better body compared to another. For instance, fish have evolved a streamlined design as it is best suited for an aquatic environment. On the other hand, a spider or a chimpanzee might be ill-equipped to survive in such aquatic environments.

Exercises Page: 159

1. A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers, but almost half of them were short. This suggests that the genetic makeup of the tall parent can be depicted as

Correct answer – (c)

TtWW might be the genetic makeup of the tall parent. Since half the progenies are short, this implies that the parent plant also will have a collection of short genes; all progenies bore violet flowers, further suggesting that violet colour is dominant over white.

2. An example of homologous organs is

(a) Our arm and a dog’s foreleg

(b) Our teeth and an elephant’s tusks

(d) All of the above

Correct answer – (d)

Homologous organs have the same origin as each of the above organs but different functions. Homologous organs can be defined as the organs of various animals having similar basic structures but different functions. For example, a whale’s flippers, a frog’s forelimbs, and a man have the same basic structures but perform different functions, which is why they are called homologous organs.

3. In evolutionary terms, we have more in common with

(a) A Chinese schoolboy

(b) A chimpanzee

(d) A bacterium

Correct answer – (a)

Humans and chimpanzees are related since they belong to the identical order (Primates) and the same family (Hominidae). However, a schoolboy, regardless of ethnicity, is still a Homo sapien.

4. A study found that children with light-coloured eyes are likely to have parents with light-coloured eyes. On this basis, can we say anything about whether the light eye colour trait is dominant or recessive? Why or why not?

Knowledge of at least 3 generations is required to find if an attribute is dominant or recessive. Hence, it is not possible to identify if the given trait is dominant or recessive.

5. How are the areas of study – evolution and classification – interlinked?

Classification and evolution are two related fields of biology. Evolution pertains to how organisms evolve, and classification deals with finding out how two species are related to each other. For example, evolution and fossil evidence point to the fact that Australopithecus afarensis is considered one of our earliest ancestors. And classification tells us that Australopithecus afarensis belongs to the genus Homo, which is also the same genus as modern humans.

6. Explain the terms analogous and homologous organs with examples.

Homologous organs are those organs that have the basic structural design as well as the origin; however, they serve different functions. For example, the forelimbs of humans and the wings of bats are anatomically similar.

Analogous organs are those organs that have a different structural design as well as origin; however, they perform similar functions. For example, the wings of birds and insects.

7. Outline a project which aims to find the dominant coat colour in dogs.

Dogs have a certain set of genes that govern coat colour. There are a minimum of eleven known sequence series (A, B, C, D, E, F, G, M, P, S, T) that influence the colour of a dog. A dog inherits one copy from each of its parents. As an example, within the B series, a dog is genetically black or brown. Assume that one parent is homozygous black (BB), whereas the other parent is homozygous brown (bb).

NCERT Solutions for Class 10 Chapter 9 Image 2

In this case, all the offspring are going to be heterozygous (Bb).

Since black (B) is dominant, all the offspring are going to be black. However, they are going to have each B and b alleles. If such heterozygous pups are crossed, they are going to produce 25 homozygous blacks (BB), 15 heterozygous black (Bb), and 25 homozygous brown (bb) offspring.

NCERT Solutions for Class 10 Chapter 9 Image 3

8. Explain the importance of fossils in deciding evolutionary relationships.

Fossils give evidence about:

(a) The organism and their paleobiology

(b) Even the behaviour of an organism can be deduced to some extent (for example, palaeontologists) have unearthed a site with more than 10,000 skeletons of a dinosaur called Hadrosaurus. This implies that the dinosaur lived in herds.

(c) Fossils also provide insight into the evolutionary history of animals and plants (for instance, palaeontologists have discovered that whales had evolved from goat-sized land-dwelling animals called Pakicetus).

9. What evidence do we have for the origin of life from inanimate matter?

The evidence on the origin of life from inanimate matter was provided by Stanley L. Miller and Harold C. Urey’s experiment, which was conducted in 1953. They created an artificial environment which was reminiscent of the early earth’s atmosphere – it contained ammonia, hydrogen and other gases which were thought to have existed during primordial earth.

This concoction of gases was kept at a temperature slightly below 100 ° C. Additionally, sparks were generated to simulate lightning, which was also thought to be common during that period. At the end of the experiment, he was able to create 11 out of the 20 amino acids which are required for life.

10. Explain how sexual reproduction gives rise to more viable variations than asexual reproduction. How does this affect the evolution of those organisms that reproduce sexually?

Sexual reproduction causes a lot of viable variations because of the following reasons:

(a) Error in copying of DNA (though it was rare)

(b) Random segregation of paternal and maternal chromosomes at the time of sex cell formation.

(d) Accumulation of variations occurred because of reproduction over generation after generation, and choice naturally created wide diversity.

(e) In the case of asexual reproduction, variation is severely limited as there is only one parent involved. Hence, the offspring is genetically similar to the parent

11. How is the equal genetic contribution of male and female parents ensured in the progeny?

Equal genetic contribution of male and female parents is ensured in progeny through the inheritance of equal numbers of chromosomes from both parents. There are 23 pairs of chromosomes, but not all are paired. The 22 pairs are called autosomes, while the remaining 1 pair is called the sex chromosomes (represented as X and Y.)

Females have two sets of X-chromosomes, while males have one X-chromosome and one Y-chromosome.

During the process of reproduction, fertilisation takes place, where the male gamete fuses with the female gamete, and it results in the formation of a diploid zygote. Furthermore, the zygote receives an equal contribution of genetic material from both parents. The male contributes 22 autosomes plus one X or Y chromosome. The female contributes 22 autosomes plus one X-chromosome.

12. Only variations that confer an advantage to an individual organism will survive in a population. Do you agree with this statement? Why or why not?

The statement holds true – only variations provide an advantage to individual organisms that will survive in a population. For example, variations that lead to the increase in heat resistance in bacteria are very useful for survival if they find themselves in an environment where there is a sudden increase in ambient temperature. This will determine the difference between life and death for the bacteria.

Chapter 9 – Heredity and Evolution are expected to have between 1 to 3 marks based on the yearly trends.

In 2018, however, only 1 question was asked (regarding Laws of Inheritance) in the Class 10 Science exam. But it would be wise to learn all the relevant concepts in order to avoid any unpleasant surprises.

The topics covered in this chapter are listed below:

Laws of Inheritance
Mendel’s Experiments
Monohybrid Cross
Dihybrid Cross
Evolution and Its Theories
Evidence of Evolution

It is necessary to know how physical characteristics and traits are passed from a parent to his offspring. Furthermore, heredity provides a lot of insight into how genetics play a major role in organisms. Evolution is a gradual process where an organism changes and adapts to many variables. Sometimes, it is driven by the environment or competition.

Explore the definition of heredity and evolution. Discover its significance and implications. Find more learning resources on NCERT Solutions to aid your CBSE Board exam preparation and streamline your last-minute revisions.

Key Features of NCERT Solutions for Class 10 Science Chapter 9 Heredity and Evolution

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Tailored to meet CBSE-prescribed norms
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Nearly all jargons are explained in detail
Access to a plethora of additional learning tools and resources ranging from sample papers to solved previous year question papers

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Important Questions for CBSE Class 10 Science Chapter 9 - Heredity and Evolution 2024-25

CBSE Class 10 Science Chapter-9 Important Questions with Answers - Free PDF Download

Heredity and Evolution is an important chapter that covers the concepts of heredity, sexual reproduction, how evolution takes place, etc. Solving the Class 10 Science Ch 9 Important Questions will help students lay a strong foundation of these concepts. At Vedantu we provide students with solved important questions for Class 10 Heredity and Evolution PDF file . These questions will help students to score well in their examination. They can download and refer to the solved Class 10 Science Chapter 9 important questions PDF for free from Vedantu. Vedantu is a platform that provides free CBSE Solutions (NCERT) and other study materials for students. Maths Students who are looking for the better solutions, they can download Class 10 Maths NCERT Solutions to help you to revise complete syllabus and score more marks in your examinations.

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Study Important Questions for Class 10 Science Chapter 9 – Heredity and Evolution

Very Short Answer Questions (1 Mark)

1. Select the group which shares the maximum number of common characters-

Two genera of two families

Two species of a genus

Two genera of a family

Two individuals of a species

Ans: (d) Two individuals of a species

2. Two pea plants, one with round green seeds (RRyy) and another with wrinkled yellow (rrYY) seeds produce ${{F}_{1}}$ progeny having round, yellow (RrYy) seeds. When ${{F}_{1}}$ plants are selfed, the ${{F}_{2}}$ progeny will have the following combination of characters

Ans: (b) 9:3:3:1

3. Some dinosaurs had feathers although they could not fly birds have feathers that help them to fly. In the context of evolution, this means that-

Reptiles have evolved from birds

There is no evolutionary connection between reptiles and birds

Feathers are homologous structures in both the organisms

Birds have evolved from reptiles.

Ans: (d) Birds have evolved from reptiles.

4. What is a monohybrid cross?

Ans: The combination between two plants that display two different variants of a property (character).

5. What are autosomes and sex chromosomes?

Ans: There are 23 pairs of chromosomes in a human cell. 22 pairs are termed autosomes, while the remaining 1 pair, which determines a child's sex, is called sex chromosome.

6. Which of the following scientists gave the principles of inheritance?

Watson and Crick

Ans: (a) Mendel

7. Which of the following is not correct-

For every hormone, there is a gene.

For every protein, there is a gene.

For the production of every enzyme, there is a gene.

For every molecule of fat, there is a gene.

Ans: (a) For every protein there is a gene.

8. According to the evolutionary theory formation of a new species occurs generally due to-

Sudden creation by nature.

accumulation of variations over several generations

clones formed during asexual reproduction

Movement of individuals from one habitat to another.

Ans: (a) accumulation of variations over several generations.

9. Who coined the term ‘gene’?

Ans: The term gene was originated by Johannsen (1909).

10. What are dominant genes?

Ans: A dominant gene is one that expresses itself.

11. The concept of the origin of species by natural selection was given by.

Ans: (c) Darwin

12. If a round green seeded pea plant (RRYY) is crossed with wrinkled yellow seeded pea plant (rr yy) the seeds to be produced in F 1 generation will be.

Wrinkled and yellow

round and green

wrinkled and green

round and yellow.

Ans: (b) round and green

13. The genetic constitution of an organism is called.

Ans: (a) Genotype

14. Write the scientific name of the plant on which Mendel carried out his experiments.

Ans: Pisum sativum

15. How many autosomes are present in human sperm?

16. Two pink coloured flowers on crossing result in 1red, 2pink and 1white flower progeny. The nature of the cross is-

cross-fertilization

self-pollination

double fertilization

no fertilization

Ans: (a) cross-fertilization

17. A basket of vegetables contains carrot, potato, radish, and tomato. Which of them represent the correct homologous structure

carrot and potato

carrot and tomato

radish and carrot

radish and potato

Ans: (c) radish and carrot

18. Mendel proposed that every character is controlled by-

two factors

one chromosome

two chromosomes

Ans: (b) two factors

19. Who is called the father of genetics?

Ans: Gregor Mendel.

20. What is the scientific name of a human being?

Ans: Homo sapiens

21. The theory of chemical evolution of life was experimentally demonstrated by-

Miller and Urey

Ans: (b) Miller and Urey

22. Genetics is the study of-

resemblances amongst individuals

heredity and environment

differences amongst individuals

Heredity and variations.

Ans: (d) Heredity and variations.

23. The wing of a bird and wing of an insect is

Homologous organs

analogous organs

vestigial organ

both (a) and (b)

Ans: (a) Homologous organs

24. What is heredity?

Ans: Heredity refers to the transmission of a person's personality from one generation to the next.

25. What are Mendelian factors?

Ans: Mendelian factors are heredity components that carry on a character from parents to offspring.

26. A Mendelian experiment consisted of breeding tall pea plants bearing violet flowers with short pea plants bearing white flowers. The progeny all bore violet flowers but almost half of them were short. This suggests that the genetic make-up of the tall parent can be depicted as

Ans: (c) TtWW

27. An example of homologous organs is

Our arm and a dog’s foreleg.

Our teeth and an elephant’s tusks.

Potatoes and runners of grass.

All of the above.

Ans: (d) All of the above .

28. In evolutionary terms, we have more in common with

A Chinese schoolboy.

A chimpanzee

A bacterium

Ans: (a) A Chinese schoolboy.

29. What happened when Mendel crossed two traits of a character in a pea plant?

Ans: Mendel discovered that each feature was inherited separately from the others, resulting in its own 3:1 ratio.

30. Who provided experimental evidence to support the theory of the origin of life from inanimate matter?

Ans: Miller and Urey

31. A normal pea plant bearing coloured flowers suddenly starts producing white flowers. What could be the possible cause?

Ans: Mutation is responsible for the appearance of white flowers.

32. Mention any two recessive traits of a garden pea.

Ans: Dwarf (height of plant) and wrinkled seed.

33. What is called a phylogenetic system of classification?

Ans: Organisms are classified depending on their evolutionary relations.

34. What will be the percentage of ab gametes produced by AaBb parents?

Ans: 25 per cent

35. Mendel crossed a pure white recessive pea plant with a dominant pure red-flowered plant. What will be the first-generation f hybrids.?

Ans: Allred

36. Name the chemicals which were essential for the origin of life.

Ans: Proteins and nucleic acid

37. Why are males called heterogametic?

Ans: Males are called heterogametic because their y chromosomes are different.

39. What is the percentage possibility of a couple having daughters?

Ans: 50 per cent.

40. Name 2 organisms in which sex determination is regulated by environmental factors.

Ans: Turtle and lizard.

41. Clones of sheep are carbon copies of each other except for physical health. What kind of variation is it?

Ans: Phenotypic variation.

Short Answer Questions (2 Marks)

1. Why are acquired traits not inherited?

Ans: Acquired traits are those that organisms develop over the course of their lives. These characteristics can't be handed down because they're caused by non-reproductive tissue.

2. How evolution and classification are linked?

Ans: The organisation of organisms into groups based on their properties is known as classification. Characteristics are physical or behavioural characteristics. The most advanced and effective classification system is based on evolution. The division of organisms/species into groups reflects their shared origins, as well as their evolutionary relationship.

3. What are coacervates?

Ans: Coacervates are the first life molecules created when a membrane forms around amino acids, sugars, and nitrogenous bases aggregates. Coacervates continue to evolve, eventually leading to the origin of life.

4. How do the two factors for a character, present in diploid cells, behave at the time of gamete formation?

Ans: During gamete development, two components named X and Y separate. As a result, the gamete is either X or Y.

5. Give the pair of contrasting traits of the following characters in the plant and mention which one is recessive and which is dominant?

(a) yellow seed

Ans: Green seed- Dominant

Yellow seed- Recessive

(b) round seed

Ans: Wrinkled seed – Recessive

Round seed- Dominant

6. Mention two important features of fossils that help in evolution.

Ans: Two important features of fossils that help in evolution:

(i) Fossils are a type of ancient species preservation.

(ii) Fossils aid in the identification of evolutionary relationships between creatures and their forefathers and mothers.

7. What do you understand by the term natural selection?

Ans: Natural selection theory states that nature selects the fittest animals for breeding, while those who do not fit are removed by nature.

8. Mention the complement of a sperm and the egg which will determine the birth of a female child.

Ans: The X chromosome is found in both the sperm and the egg of a female child and it is the complement of a sperm and the egg which will determine the birth of a female child.

9. What is emasculation? Why is it done?

Ans: Emasculation is the removal of an anther to prevent pollination in an experimental plant.

10. What is a gene? Where are genes located?

Ans: The term "gene" refers to DNA segments.

Chromosomes are where genes are found.

11. How many contrasting characters did Mendel see in garden pea? Give any two of them.

Ans: In the pea plant, Mendel discovered seven distinct characteristics.

For example, axial and terminal flower positions. Round and wrinkled seed form.

12. What is the phenotypic ratio obtained by Mendel by monohybrid cross? Answer with the help of a diagram.

Ans: Mendel's monohybrid cross's phenotypic ratio isa3:1. A monohybrid cross happens when fertilisation occurs between two true-breeding parents who differ exclusively in the feature being examined, and the resulting offspring are termed monohybrids. Mendel experimented with seven different forms of monohybrid crosses, each including opposing features for various phenotypes. The F1 offspring of such crosses all had one parent's phenotype, but the F2 offspring had a 3:1 phenotypic ratio.

Mendel hypothesised that each parent in a monohybrid cross provided one amongst two paired unit factors towards each offspring, and that any potential combination of unit factors seemed equally probable.

13. Why are acquired characters not inherited?

Ans: Acquired qualities are those that organisms develop over the course of their lives.

They are not passed down to future generations. Because these characteristics are caused by non-reproductive tissues, they cannot be handed forward.

14. How is the chromosome number restored in the zygote?

Ans: Male and female gametes each have N chromosomes. Gametes combine and form a zygote during fertilisation. The number of chromosomes in a zygote is 2N.

15. What are variations? Give their types.

Ans: Despite the fact that offspring of the same parents seem the same, they are not identical to their parents. There are three distinctions between them. Variations are the term for these disparities. There are two types of it:

(a) Reproductive- It is passed down from one generation to the next.

(b) Non-reproductive—not passed down from generation to generation.

16. Write the difference between Autosomes and Allosomes.

Ans: The difference between autosomes and allosomes is as given below,

17. What will be the sex of the embryo if an egg is fertilized by the sperm having?

(a) \[22+x\] and

Ans: Female

(b) \[22+y\] composition

18. Mention two sources of variation.

Ans: Two sources of variation are:-

DNA copying errors.

Fertilization at random.

19. What are monohybrid and dihybrid cross? Give one example of each.

Ans: Monohybrid cross- This is the simplest cross in which only one character's inheritance is investigated. A cross is created by crossing two plants with one contrasting characteristic, such as tall or dwarf.

Dihybrid cross- A dihybrid cross is a cross between two plants with two sets of opposing characters. Round and green seed, for example, crossed with yellow and wrinkled seed.

20. Why did Mendel choose a pea plant for his experimentation?

Ans: Mendel chose the garden pea for his experiment for the following reasons:

Because this plant has a short life cycle, the results may be gathered and evaluated more quickly.

The garden pea possesses a number of features that are diametrically opposed to one another.

This plant is also tiny, easy to grow, and produces a big number of offspring.

21. If a trait A exists in \[\mathbf{10}%\] of a population of an asexually reproducing species and a trait B exists in \[\mathbf{60}%\] of the same population, which trait is likely to have arisen earlier?

Ans: Trait B.

22. What are the different ways in which individuals with a particular trait may increase in a population?

Ans: Individuals with a certain attribute can increase in a variety of ways, including:

Natural selection- Certain differences give individuals in a group a survival edge in a changing context, resulting in population growth.

Genetic drift—In a small population, even if no survival benefit is gained, accidents can lead to an increase in the number of specific individuals.

23. Why are traits acquired during the lifetime of an individual not inherited?

Ans: Any changes in non-reproductive organs are not passed on to germ cell DNA. As a result, qualities acquired during a person's lifetime are not inherited.

24. Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics?

Ans: The minimal number of living tigers is concerning because it could lead to a loss of genetic diversity. The abrupt demise of tigers and their genes will have an impact on natural diversity. Because the tiger population is declining, the genetic pool of tigers is shrinking. It will have an impact on the frequency of selection, which is necessary for survival. The population must have an indefinitely a vast number of individuals in order for selection to be effective.

25. Give an example of characteristics being used to determine how close two species are in evolutionary terms.

Ans: The evolutionary distance between humans and apes can be determined using the example of humans and apes. Both of their bodies are similar in appearance. Both animals have hair on their bodies and mammary glands. As a result, these two animals are tightly linked in terms of evolution.

Homologous organs share a common origin and basic structure, although they serve diverse purposes in different organisms.

Analogous organs have similar functions but vary in basic anatomy.

Homologous organs have evolved in different ways.

Analogous organs have evolved in a similar way. They form in creatures that are connected to one another.

26. Can the wing of a butterfly and the wing of the bat be considered homologous organs?

Ans: No, while the function of the wing is identical in both cases, the structural plan and origin are not.

27. Why are human beings who look so different from each other in terms of size, colour and looks said to belong to the same species?

Ans: Humans differ from one another in terms of size and colour, but they are all members of the same species. This is due to the fact that, despite the tremendous diversity of human shapes and traits among different human races around the world, all human beings' genetic footprints can be traced back to the same common heritage of African origins. Humans are a single species that descended from the earliest members of the human species in Africa, Homo sapiens. Because there has been no well-defined geographical or reproductive isolation among members of the human species, this has resulted in a wide range of genetic makeups for features with minor differences.

28. In evolutionary terms, can we say which among bacteria, spiders, fish and chimpanzees have a ‘better’ body design? Why or why not?

Ans: We can't say whether germs, spiders, fish, or chimps have a "superior" body design in evolutionary terms. The idea that various animals have better bodily designs is unjustifiable. Because the evolutionary process considers the development of the most efficient and suitable elements in organisms' body designs for survival and adaptation to a specific niche. Organisms with a complex and ostensibly better body architecture, for example, may not be able to live in a given context. Bacteria, on the other hand, can survive in the most hostile and severe environmental circumstances, such as extremely hot, cold, or acidic, due to their rudimentary body design and simple microbial lifestyle. Bacterial microorganisms can be found deep beneath arctic ice, in deserts, near volcanic eruptions on the surface of the world, at thermal vents under the deep sea or on the surface of the globe, and even in outer space.

29. How are the areas of study- evolution and classification interlinked?

Ans: Organisms are categorised into categories based on the similarities and differences they have with one another. The more features that two species share, the more closely they are related. The proximity of the two species shows that they shared a similar ancestry. As a result, species taxonomy reflects their evolutionary relationship.

30. Explain the importance of fossils in deciding evolutionary relationships.

Ans: The importance of fossils in deciding evolutionary relationships:

The study of fossils allows us to estimate how far back creatures' evolutionary relationships go.

Knowing the age of fossils allows us to determine which organisms evolved first and which evolved later.

31. Write the characteristics on the basis of which duck-billed platypus is considered as a link between reptiles and mammals.

Ans: Laying of eggs is a feature that resembles reptiles, whereas the presence of mammary glands is a characteristic that resembles mammals.

32. Why are the small number of surviving tigers a cause of worry from the point of view of genetics?

Ans: As the tiger population declines, genes are lost from the gene pool, which means there can be no recombination or variants, and hence no evolution.

33. How one is adopted to perform different functions? Give one example

Ans: One modification that occurred early in evolution is now utilised to accomplish additional functions. Feathers, for example, evolved for warmth before being modified for flying.

34. Why are asexually reproducing organisms capable of showing hereditary features?

Ans: Asexual reproduction tends to preserve the genetic similarities among all members of a line of descent. As a result, asexually reproducing organisms can exhibit hereditary characteristics.

35. If the sperm bearing Y-chromosome fertilizes the egg, the child born will not be entirely like his father. Why is it so?

Ans: If the sperm bearing Y-chromosome fertilizes the egg, the child born will not be entirely like his father because the X-chromosome, the other sex chromosome, will also have an impact. Other egg autosomes will also display their properties.

36. In evolutionary terms, which among-bacteria, spiders, fish and chimpanzees have a “body design''? Why or why not?

Ans: Chimpanzees have a better bodily design than the other species. They have greater movement, communication, and reasoning abilities.

37. What is offspring?

Ans: Offspring are organisms that are raised as a result of gene segment crossing and exchange in sexual reproduction.

38. What have inherited traits? Give one example.

Ans: Inherited traits are characteristics that are passed on from parents to their children. For example, earlobes are both free and attached.

39. When Mendel crossed a tall plant with a dwarf plant, no medium height plants were obtained in F generation. Why?

Ans: When Mendel crossed a tall plant with a dwarf plant, no medium height plants were obtained in F generation because dominant genes express themselves and prevent recessive genes from having an influence. As a result, no plants of medium size were obtained.

40. The human hand, cat paw and horse foot when studied in detail show the same structure of bones and point towards a common origin.

i. What do you conclude from this?

Ans: We can deduce that these organs share a common ancestor.

ii. What is the term given to such structures?

Ans: Homologous organs are those that are identical to one another.

41. How do we know how old a fossil is?

Ans: There are two techniques:

Relative method: When we delve into the earth, we find that the fossils found closer to the surface are more recent than those found in deeper levels.

In the fossil material, by measuring the ratios of different isotopes of the same element.

42. What will be the sex of a baby if sperm carrying the X chromosome fertilizes the egg in human beings? Why?

Ans: It will be a female since the fusion of gametes containing X chromosomes produces a homozygous zygote with the XX composition.

43. Feather imprints were preserved along with the dinosaur’s bones but dinosaurs could not fly. What was the significance of feathers in reptiles and later on for other species?

Ans: Dinosaur feathers are thought to have offered protection in cold temperatures, but they eventually became beneficial for avian flight.

44. What will be the blood groups of offspring produced by the parents having the following genotype?

Cross showing combination of Blood groups formed

Blood groups will be:

45. A woman with blonde curly hair married a man with black soft hair. All of their children in the first generation had black soft hair but in the next generation, children had different combinations in the ratio of 9:3:3:1. State the law that governs this Expression.

Ans: The law of independent assortment holds that the factors of various pairs of opposing traits are unaffected by one another. In terms of selection, they are unrelated to one another.

Short Answer Questions (3 Marks)

1. Only variations that confer an advantage to an individual organism will survive in a population. Do you agree with this statement? Why or why not?

Ans: Variations that benefit an individual organism may or may not survive in the population, depending on the organism's social behaviour. A variant in a sociable species, such as an ant, may not survive in a population, whereas a variation in a predatory animal, such as a leopard, may.

2. What are the different approaches to determine the evolutionary history of man?

Ans: There are three methods for reconstructing man's evolutionary history:

Fossil records provide direct evidence in the form of the historical approach. Carbon dating techniques can be used to establish the age of fossils.

Comparative method- By comparing multiple existing forms, we can build hypotheses about their common ancestors and reconstruct their history.

Analytic method: Observing vestigial organs in modern humans and examining their development from embryo to adult.

3. What is fossilization? How are fossils formed?

Ans: Fossilization is the term for the process of forming fossils. When organisms die, their corpses disintegrate and become fossilised. The body, or a portion of it, maybe in an environment that prevents it from fully decomposing. The mud will solidify over time and maintain the impression of the organism's bodily parts. This mud with the imprint will be referred to as an organism's fossil.

4. What are homologous and analogous organs? Explain with the help of an example.

Ans: Homologous organs have a similar basic structure and origin, but may perform diverse tasks. Human hands, for example, and avian wings, for example.

Organs that have a similar function but a different basic structure and origin are referred to as comparable organs.

For example,

a bat's wing and a bird's wing.

a bird's wing and an insect's wing

5. Differentiate between convergent and divergent evolution.

Ans: The difference between convergent and divergent evolution is as given below:

6. What are the different ways in which individuals with a particular trait may increase in a population?

Ans: Selection of environmental conditions for a species' survival are the factors that are responsible for raising a new species. If a variation exists in a population and the variation results in the organism surviving better in the prevailing natural conditions, the characteristic will be naturally selected and spread across the population.

7. What are the different theories about the origin of life?

Ans: Below given are the different theories about the origin of life:-

Special creation theory: This theory claims that the almighty god created life.

The idea of spontaneous generation- According to this theory, life sprang from non-living components by abiogenesis process including mud, decaying matter, the sun, air, and water, among other things.

Cosmozoic theory: According to this view, life came to Earth in the form of spores or seeds from distant celestial bodies.

Biogenesis—According to this hypothesis, life evolved from pre-existing life.

The modern view of life's genesis states that complex organic molecules can only be generated from simple inorganic molecules under certain conditions.

8. What is the difference between chemical evolution and organic evolution?

Ans: The difference between chemical and organic evolution is as given below,

9. Give the difference between homologous and analogous organs.

Ans: The difference between homologous and analogous organs is as given below:

10. State three laws of Mendel.

Ans: Mendel’s law-

Law of dominance- When two distinct character factors are present in an organism, only one (dominant factor) manifests itself, while the other (recessive factor) remains unexpressed.

Principle of segregation –At the moment of gamete formation, two elements of a character are separated, and each gamete receives only one factor for that character.

Principle of independent assortment- This concept asserts that one pair of contrasting qualities is independent of the other pair of contrasting traits when two or more pairs of contrasting traits are inherited.

11. Describe how the sex of the offspring is determined in the zygote ins human beings?

Ans: Males have the ability to create either X-type or Y-type gametes. The females only generate the X-type of gametes or ova. If X-type sperm unites with the ovum, the infant will have feminine sex. If Y-type sperm is used in conjunction with the ovum, the kid will be male. The baby's gender is determined at the time of conception. The baby's sex is determined at the time of conception.

12. Give a suitable explanation for “geographical isolation of individuals of a species lead to the formation of a new species?

Ans: Between the subpopulations, a reproduction barrier such as a river (geographical isolation) leads to:

Genetic drift, or chance changes in gene frequency, such as the selection of red or blue beetles over green beetles in the presence of crows.

Natural selection, or selection of the fittest by nature, e.g., in the presence of crows, green beetles are preferred over red beetles.

13. State the evolutionary force which leads to the origin of a new species.

Ans: The following are some of the evolution's elemental forces:

Mutation

Recombination (crossing over during meiosis, random gene assortment during gamete production)

Survival of the fittest or natural selection

Genetic drift is a term used to describe the process of a person's

14. What is a fossil? How do fossils tell us about the process of evolution?

Ans: Fossils are the dead remains of former live species. Paleontology is the branch of biology concerned with the study of fossils. The study of fossils reveals that species evolved from pre-existing ones or that evolution has occurred and is still occurring in nature.

15. Give the difference between diploid and haploid.

Ans: The difference between diploid and haploid is as given below:

16. Who disproved Lamarckism and how?

Ans: August Weismann established that Lamark's acquired character could not be inherited. He began cutting the rat's tail at birth and proceeded for 21 generations. Tight-lipped rats, on the other hand, were never born. Because this feature does not alter the DNA of germ cells, it cannot be passed down the generations. As a result, alterations in an individual's non-reproductive tissue during their lifespan cannot be passed on to their progeny, and hence cannot direct evolution.

17. How does Archaeopteryx provide evidence for organic evolution?

Ans: Archeopteryx contains reptile-like characteristics, dinosaur-like characteristics, and bird-like characteristics such as wings. This demonstrates that birds and reptiles are closely linked. Reptiles may have evolved into birds.

18. What is divergent evolution? Explain with the help of an example.

Ans: Divergent evolution is the process of animals with distinct appearances evolving from common ancestors. This is also known as adaptive radiation, and it refers to the evolution of new forms in multiple directions from a common ancestor type. The evolution of wild cabbage is a current example of such a process. For more than 200 years, humans have cultivated wild cabbage as a food plant and used artificial selection to produce a variety of vegetables (such as cabbage, broccoli, cauliflower, kohlrabi, and kale). As a result, all of these distinct vegetable structures are descended from the same ancestor, which is wild cabbage.

19. What is the difference between reproductive and non-reproductive variations?

Ans: The difference between non-reproductive and reproductive variation is as given below:

20. Write similarities between Mendelian’s factors and genes.

Ans: Genes, like mendelian factors, contain information about phenotypes. They are the units of inheritance that transmit from one generation to the next without turning into children.

Genes occur in the form of alleles of a gene situated on homologous chromosomes, identical to mendelian factors.

During gamete development, alleles of a gene also segregate, and each gamete obtains just one amongst the two forms, identical to mendelian factors.

One of the alternate versions of a gene is dominant over another that lowers its expression, similar to Mendelian factors.

When genes are situated on distinct chromosomes or at a distance on the very same chromosome, they segregate and assort independently, similar to Mendelian factors.

21. How does the creation of variations in a species promote survival?

Ans: Different individuals would have different sorts of advantages to adjust in a certain ecosystem depending on the nature of the variances. Variation allows individuals to create a variety of features that make creatures more bearable.

22. How do Mendel’s experiments show that traits may be dominant or recessive?

Ans: In a Mendel monohybrid cross between tall and dwarf pea plants, all progeny in the \[{{\text{F}}_{\text{1}}}\] generation is tall, while \[75\] percent of pea plants in the \[{{\text{F}}_{2}}\] generation are tall but \[25%\] are dwarf. This demonstrates whether a characteristic is dominant or recessive.

23. How do Mendel’s experiments show that traits are inherited independently?

Ans: When a round green seeded pea plant is crossed with a wrinkled yellow seeded pea plant in the \[{{\text{F}}_{\text{1}}}\] generation, all of the plants have round yellow seeds. However, two new features, round yellow and wrinkled green, develop in the \[{{\text{F}}_{2}}\] generation. This demonstrates that qualities are inherited separately.

24. A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits-blood group A or O- is dominant? Why or why not?

Ans: No, because the blood group is defined by a pair of genes, the information is insufficient. One came from the mother, while the other came from the father. In this situation, the youngster received the O blood group gene from both his mother and father.

25. How is the sex of the child determined in human beings?

Ans: A girl inheriting the X chromosome from her father will be a female, whereas a boy inheriting the Y chromosome will be a boy.

26. What factors could lead to the rise of a new species?

Ans: The following factors may contribute to the emergence of new species:

(a) In small breeding isolated populations, changes in gene frequency.

(b)Natural selection

27. Will geographical isolation be a major factor in the speciation of self-pollinating plant species? Why or why not?

Ans: No, because geographical barriers prevent breeding between sexually reproducing individuals in a community. Furthermore, asexually reproducing organisms pass on parental DNA to offspring, eliminating the possibility of speciation.

28. Will geographical isolation be a major factor in the speciation of an organism that reproduces asexually? Why or why not?

Ans: Yes, the two populations are separated due to geographical remoteness. The amount of gene flow between them will dwindle. The isolated population will breed with the local population, resulting in the isolated population being included in the new population.

29. What are fossils? What do they tell us about the process of evolution?

Ans: Fossils are preserved evidence of living animals that are found closer to the earth's surface and are more recent in origin than fossils discovered in deeper layers. Fossils can also aid in the discovery of evolutionary relationships between creatures.

30. A study found that children with light-coloured eyes are likely to have parents with light coloured eyes. On this basis, can we say anything about whether the light eye colour trait is dominant or recessive? Why or why not?

Ans: No,1 because parents pass on two copies of qualities, one from the mother and the other from the father. We can't identify which is dominant and which is recessive unless we understand the nature of these two types of attributes. When both parents contribute a recessive gene, recessive features arise. We can only assume that both parents contribute a recessive gene based on this remark.

31. Explain the terms analogous and homologous organs with examples.

Ans: Analogous organs: These are organs that have similar functions but differ in structure and origin. For example, the wings of birds and insects.

Homologous organs: Organs with identical structure and origin, but with different functions. Frog, lizard, and bird forearms are examples.

32. What evidence do we have for the origin of life from inanimate matter?

Ans: Stanley L. Miller and Harold C. Urey provided testimony in 1953. They created an atmosphere above water that was expected to exist on early Earth. They kept it at a temperature slightly below \[100\] degrees Celsius and stimulated lightning by passing sparks through the combination of gases. They discovered that \[15%\] of the carbon had been transformed to simple carbon compounds, such as amino acids, which make up protein molecules, at the end of the week.

33. Explain how sexual reproduction gives rise to more viable variations than asexual reproduction. How does this affect the evolution of those organisms that reproduce sexually?

Ans: Variations occur as a result of either DNA copying errors or sexual reproduction. Genetic heterogeneity in the population rises from generation to generation as a result of sexual reproduction. Because sexually reproducing organisms acquire half of their genes from each parent, this occurs. These differences are critical to the evolution process.

34. Only variations that confer an advantage to an individual organism will survive in a population. Do you agree with this statement? Why or why not?

Ans: No, various individuals have different kinds of advantages depending on the kind of variances. However, when the environment undergoes a radical shift, only those organisms in the population that have a beneficial variation in that population would be able to live in the new environment.

35. How is the equal genetic contribution of male and female parents ensured in the progeny?

Ans: During sexual reproduction, both male and female parents contribute equally to the child. Each progeny trait is determined by a pair of alleles, and male and female gametes each have one allele. During fertilisation, each allele pair combines to determine phenotypes. As a result, child qualities are decided by equal genes from both male and female parents.

36. Is it true that when a new species emerges, the old species is eliminated and why?

Ans: No, it is not true that as a new species emerges, the old one dies off.

Because when a species changes, it only affects a portion or a few individuals of the population. If the newly created species is better in any way, it will have a better chance of surviving, but if the genetic mutation is harmful to the environment, it will perish. As a result, unmodified members of other species may survive and thrive in a changing environment.

37. Why are traits acquired during the lifetime of an individual not inherited?

Ans: Changes in nonreproductive tissue or somatic cells cannot be passed on to the DNA of germ cells, hence traits acquired during a person's lifetime are not inherited. As a result, the acquired trait will perish with the individual's death. As a result, it is non-heritable and cannot be passed on through the generations.

38. The gene type of green stemmed tomato plants are denoted as GG and that of purple stemmed tomato plants as GG when these two are crossed.

(i) What colour of the stem would you expect in \[~{{F}_{1}}\] progeny?

Ans: Green is the colour of the \[{{\text{F}}_{\text{1}}}\] progeny.

(ii) Give the percentage of purple stemmed plants if F is self-pollinated.

Ans: In the \[{{\text{F}}_{2}}\] generation, the percentage of purple stemmed plants was \[{\scriptscriptstyle 1\!/\!{ }_4}\] or \[25%\].

(iii) In what ratio would you find the gene types CG and Gg in the F progeny?

Ans: CG and Gg genotype ratio is \[1:2\].

37. What are the causes of variations in clones?

Ans: Below given are the causes of variation in clones:-

(i) Amid DNA copying inaccuracies

(ii) Acquired variation refers to the effect of the environment.

(iii) Mutations are unidirectionally inheritable, sudden stable alterations caused by changes in genetic make-up.

38. The only variation that confers an advantage to an individual organism will survive in a population. Do you agree with this statement? Why or why not?

Ans: We concur with the assertion. All of the variations do not have an equal chance of survival in their current environment. The nature of variation affects the probability of survival. Individuals benefit from a variety of advantages. In a heatwave, microorganisms that can endure heat will do better.

39. Study the given data and answer the questions following the data: Parental plants cross-fertilize and seeds collected \[~{{F}_{1}}\] First Generation offsprings \[~{{F}_{2}}\] of offsprings of self-pollination of \[~{{F}_{1}}\] Male parents always bare red flowers, Female parent always had white flowers, 330 seeds sown and observed, all 330 gave red flowers, out of 44 seeds 33 seeds gave plants with red flowers and 11 seeds gave plants with white flowers.

(i) What is the term for this type of cross?

Ans: Monohybrid cross

(ii) What does the data of the column marked F indicate?

Ans: The red colour of the bloom takes precedence over the white flower.

(iii) Express the gene type of the (a) parents (b) \[~{{F}_{1}}\] progeny and (c) \[~{{F}_{2}}\] progeny

Parents – (RR) and (rr)

\[~{{F}_{1}}\] progeny – Rr

\[~{{F}_{2}}\] progeny – RR, Rr and rr

40. Wild cabbage was converted into a number of variants like cauliflower, broccoli and cabbage by man. What is this process known as? Does it play an important role in organic evolution?

Ans: Artificial selection is the term for this method. Because it is similar to natural selection, it plays a crucial role in biological evolution. It aids in the production of new species with beneficial features in a shorter amount of time.

41. How are variant genotypes produced?

Ans: Variant genotypes can be created using the following methods:

(i) Gene and chromosomal mutations.

(ii) Gene recombination is a process in which two or more genes combine to form offspring with combinations of traits.

(iii) Gene hybridization is a term used to describe the process of combining two or more genes.

42. Can geographical isolation lead to speciation? How?

Ans: Geographic isolation can, in fact, lead to speciation. As a result of genetic drift, members of two subgroups may not be able to interbreed due to geographical isolation. Natural selection works differently in these subgroups as well. Speciation occurs as a result of this.

Long Answer Questions (5 Marks)

1. Answer the following questions:

(i) Who provided the evidence of DNA as genetic material?

Ans: Mendel.

(ii) Why is DNA called polynucleotide?

Ans: DNA is made up of many different nucleotide units.

(iii) List three important features of the double-helical model of DNA.

Ans: Important features-

(a) In helical, both chains run antiparallel.

(b) Purine (A, G) and pyrimidine are two nitrogenous bases (T, C).

2. Give the basic features of the mechanism of inheritance.

Ans: Characteristics of the inheritance mechanism-

(a) A pair of elements influence each character. It's possible that the factors are similar or dissimilar.

(b) When two distinct character factors are present in an organism, only one of them manifests itself, while the other remains silent.

(c) At the moment of gamete production, two elements of a character are separated, leaving only one factor for that character.

(d) Inheritance of two or more pairs of contrasting features in such a way that one pair is independent of the other pairs.

3. Outline a project which aims to find the dominant coat colour in dogs.

Ans: Dogs have a variety of coats. Select a pure-bred male and female dog with a black coat (hair) colour or a pure-bred male and female dog with a brown coat (hair) colour to find the dominant coat (hair) colour in dogs. Cross a homozygous male BB with a homozygous female BB, then look at the coat colour of the offspring (offspring). If all of the progeny are black, this indicates that in dogs, black will be the dominant coat colour, and if the progeny has brown coats, brown will be the dominant coat colour.

Cross to identify dominant coat color in Dogs

And, if we make the Punnett square of the \[~{{F}_{1}}\] generation, we obtain Bb, Bb, Bb, Bb, i.e., all progeny is black. As a result, the dominant colour is determined to be black.

Learn More About Heredity and Evolution

The important questions for class 10 science chapter heredity and evolution cover every topic that is given in the chapter.

Genes can be defined as the functional unit of heredity. According to solved important questions for Heredity and Evolution Class 10, every gene is responsible for controlling one or several characteristic features in different living organisms. Class 10 Science Heredity and Evolution important questions will help students to understand the topics easily.

Heredity can be defined as the process through which various features of an organism are passed from one generation to another. This process is carried out by genes. Another important topic from which many CBSE Class 10 Science Heredity and Evolution important questions are asked is Mendel’s work.

It should be noted that Gregor Johann Mendel, who is also known as the ‘Father of Genetics’, was an Austrian Monk who worked on pea plants to explore the concept of heredity. It was his work that laid the foundation for the modern field of genetics. According to Gregor Johann Mendel, there are three basic laws of inheritance. These laws are:

The Law of Dominance

According to the law of dominance, a gene that has two contrasting alleles and the one gene always expresses itself is known as the dominant gene.

The Law of Segregation

The law of segregation states that the traits get segregated completely during the formation of gametes without any mixing of alleles.

The Law of Independent Assortment

According to the law of independent assortment, the traits can be segregated independently of different characters. This is done during the process of gamete formation.

Various concepts are related to this topic are as follows.

Dominant Traits

Dominant traits are traits that can express themselves in an organism under every possible combination. In the experiment that was carried out by Mendel, the tall trait of pea plants was dominant over the short trait.

Recessive Traits

Recessive traits are those traits that are not expressed in the presence of a dominant allele or dominant trait. Readers should remember that a recessive trait will not be expressed in the presence of a dominant allele.

Monohybrid Cross

During the crossing over of genes of two organisms, if only one trait is considered, then that type of cross is known as a monohybrid cross. Also, the monohybrid ratio is the ratio of characters that arises out of the monohybrid cross at F2 generation. The monohybrid ratio is 3:1.

Dihybrid Cross

If two characters are considered during a cross, then this type of cross is known as a dihybrid cross. The dihybrid ratio is the ratio of characters that arises out of a dihybrid cross at F2 generation. The dihybrid ratio is 9:3:3:1.

Inheritance

It is the process of transfer of traits from one generation to another in biology.

Sex Determination

Sex determination is the process in which the sex of an individual can be determined. This is done on the basis of the composition of genetic material. In various animals, the sex of an embryo is identified by considering different factors.

In human beings, the process of sex determination is carried out on the basis of the presence or absence of the Y chromosome. If XX chromosomes are present, then the child is a female and if XY chromosomes are present, then the child is a male.

Traits are characteristic features of an organism. These features are visible in a physical form or in the physiological aspect of an organism.

The different types of characters or traits are:

Acquired Characters: The characters that are acquired by an organism through experience or over the period of his or her lifetime are known as acquired characters. These characters might not be passed on to the next generation through genes.

Inherited Characters: These characters are inherited by the offspring from the parent through genes. These characters might be expressed or not expressed depending on whether the trait is dominant or recessive. For example, skin colour, height, and eye colour.

Genetic Variation

Genetic variations can be explained as the difference in the DNA sequences that are present among every organism. This leads to a varied and diverse gene pool. These differences also result in different physical characters and biochemical pathways.

Natural Selection

Natural selection can be explained as the process by which a favorable trait is selected from a population of a species. This occurs due to the changing natural conditions, which further exert equal pressure on all living organisms.

This further leads to a scenario where the organisms or species that are better adapted to coping up with the exerted pressure survive. In other words, those organisms are selected by nature and cannot perish.

Genetic Drift

Genetic drift is the process through which random fluctuations in gene variants occur due to various reasons. Genetic drift can also be defined as the change in the frequency of an existing allele in a small population. Due to genetic drift, a gene variant might completely disappear from a population. This also reduces genetic variation.

Speciation is the process through which new species are formed from existing species. This can be the result of various evolutionary forces like isolation of populations, genetic drift, and natural selection.

Students should also remember that Charles Darwin is known as the ‘Father of Evolution.’ He was an English biologist and naturalist. He wrote a theory of evolution, which was published in a book called Origin of Species in 1859.

Now, let’s move to the topic of evolution. Evolution can be best explained as a type of tangible change in the heritable characteristics of a population. This change occurs over several generations. For evolution, new species arise or the pre-existing species might become better at dealing with several environmental stressors.

There is also a theory on the origin of life. This theory was given by J. B. S. Haldane, who was a British scientist. According to this theory, life originated from lifeless and organic matter. This theory was proved to be correct by an experiment that was carried out by Urey and Miller. This theory is also known as the theory of abiogenesis. There is also much evidence that supports the theory of evolution. One of those evidences is fossils. Fossils can be defined as the preserved remains of ancient animals or plants that died millions of years ago. These fossils help scientists to understand the physiology and anatomy of organisms that existed millions of years ago on earth. This is the biggest evidence of how evolution worked and led to the formation of organisms that exist on earth today.

We know that humans belong to the primate family, and there are many studies that prove that humans have a very close genetic connection to chimps and other primate organisms. According to several theories on human evolution, it has been stated that some ancestors of human beings are Dryopithecurs, Ramapithecus, Homo erectus, Ramapithecus, neanderthalensis, and Cro-magnon man. Interestingly, the story of human evolution has also been traced back to Africa.

Why Should You Download Important Questions of Heredity and Evolution Class 10 From Vedantu?

There are many reasons for downloading the important questions of Heredity and Evolution chapter from Vedantu. Some of these reasons are:

All questions and answers are framed by the highly experienced academic experts.

These questions are as per the latest syllabus of CBSE Class 10 .

It becomes easier to revise all the topics covered in this chapter by referring to these questions and answers from the this PDF.

Solving and practicing these important questions will help students to score well in the exams.

Also, the important questions PDF is available for free download on Vedantu, hence accessible for all students.

Apart from solved important questions for class 10 science heredity and evolution PDF, Vedantu also provides students with online live classes. Students can join these classes for a better learning experience.

Important Related Links for CBSE Class 10 Science

Reviewing all the crucial questions for Class 10 Science Chapter 9 - Heredity and Evolution provides students with a solid grasp of the chapter's topics. The extra and important questions for Class 10 Science Chapter 9 - Heredity and Evolution engage in a concept-focused discussion encompassing all chapter themes. This question-and-answer method proves time-saving during exam prep, offering an efficient way to revise the chapter and enhance understanding. Practicing these important questions streamlines preparation and boosts confidence for the upcoming exams.

FAQs on Important Questions for CBSE Class 10 Science Chapter 9 - Heredity and Evolution 2024-25

1. Does Vedantu Provide Class 10 Heredity and Evolution Important Questions for Download?

Yes, students can download Class 10 Heredity and Evolution important questions PDF from Vedantu. This PDF file is available for free download. So, all that you have to do is simply install the Vedantu app and start practicing the questions.

2. What are the Important Topics Covered in Class 10 Science Chapter 9 Important Questions?

Some important topics of Chapter 9 of Class 10 Science NCERT book are:

Understanding DNA and RNA.

The evidence for considering DNA as the genetic material.

The mechanism of inheritance and evolution.

3. What do You Understand by Human Evolution?

Humans belong to the primate family and the story of human evolution has been traced back to the continent of Africa. According to studies, human evolution occurred in the following chain.

Dryopithecus → Ramapithecus → Australopithecus → Homo erectus → Homo neanderthalensis → cro-magnon man → Homo sapiens.

4. Why is hereditary variation important according to Chapter 9 of Class 10 Science?

Heredity is about traits and characters being transferred from parents to offspring. Hereditary variation includes variation in the genomes that alter genes in all organisms. Genetic variation is essential for the survival of the species because growth is restricted in the case of definite disparity in genes. Also, evolution in different generations comes with genetic enhancement and variations. For example, you may have similar traits and looks as your great-grandparents but your personality is more like that of your parents.

5. What is the basis of evolution as explained in Chapter 9 of Class 10 Science?

Evolution is based on the theory that constant changes take place in the living organisms over many years to form new species. Charles Darwin also proposed the theory of evolution which states that it is natural to have some variation. Evolution occurs because some organisms are not fit to live in the available surroundings. Thus, changes take place in the organisms so that they can live comfortably in the available environment which leads to the evolution of new species.

6. What are the carriers of genes according to Chapter 9 of Class 10 Science?

Genes are carried by chromosomes. Genes are transmitted from parents to offspring through chromosomes. An equal number of chromosomes are shared from both parents to produce new offspring. Some genes from each parent are transmitted to the child. Genes are responsible for transmitting hereditary characters from parents to children. Genes are present on chromosomes. Genes control one or more characteristic features in living organisms. Students will study the concept of genes and chromosomes and other related topics in Chapter 9 of Class 10 Science.

7. What do you understand about dominant and recessive traits as discussed in Chapter 9 of Class 10 Science?

Dominant traits mean the traits can express themselves when combined in any form. Recessive traits mean they cannot express themselves if a dominant trait is present. If a dominant allele is present then the recessive trait could not be expressed. For example, an experiment carried by Mendel showed that the tall trait was dominant and the short trait was recessive. Students can understand the Concepts Of Chapter 9 of Class 10 Science from the important questions available on Vedantu related to the chapter. These study material can be downloaded free of cost from Vedantu’s official website (vedantu.com)

8. What are acquired and inherited traits according to Chapter 9 of Class 10 Science?

Acquired traits are the characteristics that are acquired by a living organism during a lifetime and they are not transmitted from parents to children. Acquired traits are unique and are not passed from one generation to another. Inherited traits means the characteristics of an individual that are acquired or passed on from parents to children. Inherited traits are transmitted through genes from parents to children and are passed on from one generation to another.

CBSE Class 10 Science Important Questions

Cbse study materials.

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Case Study Question for Class 10 Science (CBSE Board)

Case Study Question Class 10 Science for CBSE Board: Understudies can discover the chapter astute vital questions for course 10th Science within the table underneath. These imperative questions incorporate questions that are regularly inquired in a long time. Moreover, arrangements are to give for these questions, with extraordinary accentuation on ease-of-study. Tap on the joins underneath to begin investigating.

Case Study Question for Class 10 Science Ch. 1 to 16

Case study: 1.

1) Sahil performed an experiment to study the inheritance pattern of genes. He crossed tall pea plants (TT) with short pea plants (tt) and obtained all tall plants in F1 generation. (CBSE Sample Paper 2022)

a.) What will be set of genes present in the F1 generation? (1 Mark)

b.) Give reason why only tall plants are observed in F1 progeny. (1 Mark)

Ans. Traits like ‘T’ are called dominant traits, while those that behave like ‘t’ are called recessive traits./Alternatively accept the definition of dominant and recessive traits with examples of T and t respectively /Alternatively accept the law of Dominance with examples of T and t.

c.) When F1 plants were self – pollinated, a total of 800 plants were produced.

How many of these would be tall, medium height or short plants? Give the genotype of F 2 generation. (2 Marks)

When F1 plants were cross – pollinated with plants having tt genes, a total of 800 plants were produced. How many of these would be tall, medium height or short plants? Give the genotype of F 2 generation.

Ans. Out of 800 plants 600 plants will be tall and 200 plants will be small, 1

TT: 2Tt: 1tt (1 mark)

In the cross between Tt X tt, 400 Tall (Tt) and 400 short (tt) plants will be produced.

Case Study: 2 Question Class 10 Science

2) Ansari Sir was demonstrating an experiment in his class with the setup as shown in the figure below. (CBSE Sample Paper 2022)

case study questions and answers class 10 science

A magnet is attached to a spring. The magnet can go in and out of the stationary coil.

He lifted the Magnet and released it to make it oscillate through the coil. Based on your understanding of the phenomenon, answer the following questions.

a.) What is the principle which Ansari Sir is trying to demonstrate?

Ans. Sir is trying to demonstrate the principle of Electromagnetic induction.

b.) What will be observed when the Magnet starts oscillating through the coil. Explain the reason behind this observation.

Ans. There will be induced current in the coil due to relative motion between the magnet and the coil. Changing the magnetic field around the coil generates induced current.

c.) Consider the situation where the Magnet goes in and out of the coil. State two changes which could be made to increase the deflection in the galvanometer.

Is there any difference in the observations in the galvanometer when the Magnet swings in and then out of the stationary coil? Justify your answer.

Using a stronger magnet, using a coil with more number of turns.

When the magnet moves into the coil, the ammeter shows a momentary deflection towards one side say left.

When the magnet moves out of the coil, the ammeter shows a momentary deflection now towards right.

This is due to changing magnetic field /flux associated with the coil as the magnet moves in and out.

Alternatively, the flux increases when the magnet goes in and it decreases when the magnet goes out.

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NCERT Solutions for Class 10 Science Chapter 9 Heredity and Evolution

Chapter 9 Heredity and Evolution Class 10 NCERT Solutions

Ncert solutions for class 10 science chapters:, why are acquired characters not inheritable, what do you mean by chromosome, how can we trace evolutionary relationships, what is dna copying, what is the effect of dna copying which is not perfectly accurate on the reproduction process, contact form.

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CBSE 10th Standard Science Subject Case Study Questions

By QB365 on 21 May, 2021

QB365 Provides the updated CASE Study Questions for Class 10 , and also provide the detail solution for each and every case study questions . Case study questions are latest updated question pattern from NCERT, QB365 will helps to get more marks in Exams

QB365 - Question Bank Software

10th Standard CBSE

Final Semester - June 2015

Redox reactions are those reactions in which oxidation and reduction occur Simultaneously. A redox reaction is made up of two half reactions. In the first half reaction, oxidation takes place and in second half reaction, reduction occurs. Oxidation is a process in which a substance loses electrons and in reduction, a substance gains electrons. The substance which gains electrons is reduced and acts as an oxidising agent. On the other hand, a substance which loses electrons is oxidised and acts as a reducing agent. (i) Which of the following is a redox reaction?

(ii) Identify the reaction in which H2 02 is acting as a reducing agent.

(iii) For the following reactions, identify the one in which H 2 S acts as a reducing agent.

(iv) For the following reaction, identify the correct statement. $\mathrm{ZnO}+\mathrm{CO} \longrightarrow \mathrm{Zn}+\mathrm{CO}_{2}$

(v) In the following reaction, which substance is reduced? $\mathrm{PbS}+4 \mathrm{H}_{2} \mathrm{O}_{2} \longrightarrow \mathrm{PbSO}_{4}+4 \mathrm{H}_{2} \mathrm{O}$

(ii) If the pH of a solution is 8, then its [H + ] ion is

(iii) In terms of acidic strength, which one of the following is in the correct increasing order?

(iv) Which of the following compounds does not give H + ions in aqueous solution?

(v) Four solutions labelled as P, Q, Rand Shave pH values 1, 9, 3 and 13 respectively. Which of the following statements about the given solutions is incorrect?

Baking powder produces carbon dioxide on heating, so it is used in cooking to make the batter spongy. Although, baking soda also produces CO 2 on heating, but it is not used in cooking because on heating, baking soda produces sodium carbonate along with carbon dioxide. Sodium carbonate, thus, produced, makes the taste bitter. Baking powder is the mixture of baking soda and a mild edible acid. Generally, tartaric acid is mixed with baking soda to make baking powder. When baking powder is heated, NaHCO 3 decomposes to give CO 2 which makes bread and cake fluffy. Tartaric acid helps to remove bitter taste due to formation of sodium tartrate. $2 \mathrm{NaHCO}_{3}+ \ \ \mathrm{C}_{4} \mathrm{H}_{6} \mathrm{O}_{6} \quad \longrightarrow \quad 2 \mathrm{CO}_{2}+2 \mathrm{H}_{2} \mathrm{O}+\mathrm{Na}_{2} \mathrm{C}_{4} \mathrm{H}_{4} \mathrm{O}_{6}$ Baking soda Tartaric acid Carbon dioxide Sodium tartrate (i) On passing excess CO 2 gas in aqueous solution of sodium carbonate, the substance obtained is

(ii) When sodium hydrogen carbonate is added to acetic acid, it evolves a gas. Which of the following statements are true about the gas evolved? (I) It turns lime water milky (II) It extinguishes a burning splinter (III) It dissolves in a solution of sodium hydroxide (IV) It has a pungent odour

(iii) Select the correct statement regarding sodium hydrogen carbonate.

(iv) Acetic acid was added to a solid X kept in a test tube. A colourless and odourless gas was evolved. The gas was passed through lime water which turned milky. It was concluded that

(v) Which of the following statements are correct regarding baking soda? (I) Baking soda is sodium hydrogen carbonate (II) On heating, baking soda gives sodium carbonate (III) It is used for manufacture of soap (IV) It is an ingredient of baking powder

The chemical reactivity of an element depends upon its electronic configuration. All elements having less than eight electrons in the outermost shell show chemical reactivity. During chemical reactions, atoms of all elements tend to achieve a completely filled valence shell. Metals are electropositive in nature. They have tendency to lose one or more electrons present in the valence shell of their atoms to form cations and achieve nearest noble gas configuration. The compounds formed by the transfer of electrons from one element to other are known as ionic or electrovalent compounds. (i) The electronic configurations of three elements X, Y and Z are: X : 2 Y: 2, 8, 7 Z : 2, 8, 2 Which of the following is correct regarding these elements?

(ii) Element X reacts with element Y to form a compound Z. During the formation of compound Z, atoms of X lose one electron each whereas atoms of Y gain one electron each. Which of the following properties is not shown by compound Z?

(iii) Which of the following is correct representation of formation of magnesium chloride?

(iv) The electronic configuration of sodium ion is

(v)Which of the following represents an electropositive element?

A hydrocarbon (P) has the molecular formula C 10 H 22 .A hydrocarbon (Q) has two carbon atoms less than (P) and belong to the same homologous series. A hydrocarbon (R) has two carbon atoms more than (P) and belong to the same homologous series. (i) What is the molecular formula of (Q) ?

(ii) To which homologous series do the compound (P), (Q) and (R) belong?

(iii) What is the molecular formula of (R) ?

(iv) Identify the correct statement about compounds (P), (Q) and (R) .

(v) Compounds (P), (Q) and (R) are

The recurrence of properties of the elements after a certain regular intervals, when they are arranged in the increasing order of their atomic numbers, is called periodicity. There are a number of physical properties such as atomic size, metallic and non -metallic character, etc. which show periodic variation. In periodic table, various properties vary differently from moving left to right in a period and going down in a group. In a period, properties vary because from moving left to right in a period, number of shells remain same but valence electron increases by one number hence nuclear charge increases. In a group, on going down, number of valence shells increases while number of valence electrons remains same. (i) From top to bottom in a group of the periodic table, the electropositive character of the element

(ii) Which element has the largest size in the second period?

(iii) Which of the following elements has three valence electrons?

(iv) In the periodic table, the metallic character of elements (a) decreases from left to right and decreases down the group (b) decreases from left to right and increases down the group (c) increases from left to right and increases down the group (d) increases from left to right and decreases down the group (v) Which of the following increases along the period?

The small intestine is the longest part of the alimentary canal. It is a narrow tube of about 6 metres which lies coiled in the abdomen. The length of small intestine varies in different animals depending on the type of food they eat. (i) Humans are not able to digest cellulose whereas they are able to digest starch due to

(iii) Butter cannot be digested in the stomach as lipase and bile are(a) released in small intestine

(iv) Which of the following is a correct statement? (a) Herbivores have shorter small intestine as they eat grasses (b) Carnivores have larger small intestine as they eat meat (c) Herbivores have larger small intestine as they eat grasses (d) None of these (v) Various types of movements are generated by the ______ layer of the small intestine.

(iii) Which of the following animals shows double circulatory pathway?

(v) Select the option which properly represents pulmonary circulation in humans. $\text { (a) Left auricle } \frac{\text { Deoxygenated }}{\text { blood }}{\longrightarrow} \text { Lungs } \frac{\text { Oxygenated }}{\text { blood }} \text { Right ventricle }$ $\text { (b) Left auricle } \frac{\text { Oxygenated }}{\text { blood }}{\longrightarrow} \text { Lungs } \frac{\text { Deoxygenated }}{\text { blood }}{\longrightarrow} \text { Right ventricle }$ $\text { (c) Right ventricle } \frac{\text { Deoxygenated }}{\text { blood }}{\longrightarrow} \text { Lungs } \frac{\text { Oxygenated }}{\text { blood }} \rightarrow \text { Left auricle }$ $\text { (d) Right ventricle } \frac{\text { Oxygenated }}{\text { blood }}>\text { Lungs } \frac{\text { Deoxygenated }}{\text { blood }} \gg \text { Left auricle }$

Spore formation, method of asexual reproduction is used by unicellular as well as multicellular organisms.Spores are microscopic units which could be air borne or are present in soil, etc. (i) A slice of bread kept in open for sometime shows growing white cottony mass which later turns black. This happens because (a) bacterial spores present in air germinate on the surface of bread slice (b) fungal spores present in air germinate on the surface of bread slice (c) protozoan microbes start feeding on bread slice (d) none ef these. (ii) Spore formation can be seen in

(iii) Bulb like structure at top of erect hyphae where spores are produced is

Gregor Mendel conducted hybridisation experiments on garden peas for seven years and proposed the laws of inheritance in living organisms. He investigated characters in the garden pea plant that were manifested as two opposing traits, e.g., tall or dwarf plants, yellow and green seeds, etc. (i) Among the seven pairs of contrasting traits in pea plant as studied by Mendel, the number of traits related to flower, pod and seed respectively were

(ii) The colour based contrasting traits in seven contrasting pairs, studied by Mendel in pea plant were

(iii) Refer to the given table of contrasting traits in pea plants studied by Mendel.

Which of the given traits is correctly placed? (a) (i), (ii) and (iii) only (b) (ii), (iii) and (iv) only (c) (ii) and (iii) only (d) (i), (ii), (iii) and (iv) (iv) Some of the dominant traits studied by Mendel were (a) round seed shape, green seed colour and axial flower position (b) terminal flower position, green pod colour and inflated pod shape (c) violet flower colour, green pod colour and round seed shape (d) wrinkled seed shape, yellow pod colour and axial flower position. (v) Which of the following characters was not chosen by Mendel?

(ii) The angle between the incident ray and the emergent ray is called

(iii) When a ray is refracted through a prism, then

(iv) The angle of deviation depends on

(v) The rectangular surfaces of a prism are known as

Some harmful non-biodegradable chemicals, i.e., pesticides (e.g., DDT) and heavy metals (e.g., mercury, arsenic cadmium, etc.) enter the bodies of organism through the food chain and go on concentrating at each trophic level. This phenomenon is called bio-magnification or biological magnification. (i) Refer to the given food chain Phytoplankton $\longrightarrow$ Zooplankton $\longrightarrow$ Small fish $\longrightarrow$ Large fish $\longrightarrow$ Fish eating birds If concentration of DDT in small fish is estimated to be 0.5 ppm, then amount of DDT in zooplankton and large fish would respectively be

(ii) Refer to the given table.

According to the given data. The correct order in a food chain will be

(iv) Higher amount of DDT disturb calcium metabolism of birds. This results in

(v) When animals are sprayed with poisons, they may die immediately, but their bodies still contain the poison. The poison in their bodies will then be passed on to the animals which eat them. What would be the consequence of a mass poisoning of the rabbit population in a grazing food chain and why? (a) Plants would die quickly as they are eaten by rabbits (b) Grasshopper would die quickly as all the animals in the food web would be affected (c) Western rattlesnakes would quickly become poisoned as they eat rabbits (d) Hawk would become poisoned as they feed on rabbits

(v) Greenhouse effect is due to

Energy flow is the key function of an ecosystem. It is determined by the two basic laws of thermodynamics. Flow of energy in our ecosystem is unidirectional. Green plants capture approximately about 1% of the solar energy incident on the earth to carry out the process of photosynthesis. In an ecosystem, transfer of energy follows 10 percent law, i.e., only 10% energy is transferred from one trophic level to another and remaining 90% of energy is lost in respiration. (i) Read the given statements and select the incorrect one(s). I. At each trophic level organisms utilise energy in respiration. II. Only 10 percent of the solar radiations that fall on earth is used by green plants. III. Green plants are the ultimate source of entire energy as most of the food chain begin with them. IV. A food chain usually consist of 3-4 trophic levels.

(ii) Refer to the given flow chart. Plants $\rightarrow$ Rat $\rightarrow$ Snake 20 units 2 units 0.2 unit The given flow chart states that (a) flow of energy in an ecosystem is unidirectional (b) as we move along in a food chain the number of individuals at each trophic level decreases (c) only 10% of the total energy becomes available to next trophic level (d) both (a) and (c). (iii) Nearly 90% of the energy is wasted while moving from one trophic level to other. This energy is used in

(v) Which of the following correctly states the processes involved in energy transfer between the trophic levels?

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Cbse 10th standard science subject case study questions answer keys.

(I) (b) : H 2 is oxidised to HCI while Cl 2 is reduced to HCl. (ii) (c) $(iii) (c): 2 \mathrm{Fe} \mathrm{Cl}_{3}+\mathrm{H}_{2} \mathrm{~S} \longrightarrow 2 \mathrm{FeCl}_{2}+2 \mathrm{HCl}+\mathrm{s}$ H 2 Sitself gets oxidised to Sand reduces FeCl 3 to FeCI 2 (iv) (a ): ZnO is reduced to Zn and CO is oxidised to CO 2 (v) (b) : H 2 O 2 is reduced to water by removal of oxygen.

(i) (c): As the pH value increases from 7 to 14, it represents decrease in H+ ion concentration in the solution. (ii) (c) : pH = -log l0 [H + ] = 8 log l0 [H + ] =-8 [H + ] = 10 - 8 mol/L (iii) (a) (iv) (b): C 2 H 5 OH is not an ionic compound, it is a covalent compound and hence does not give H + ions in aqueous solution. (v) (c) : (a) Lower the pH of the solution, more acidic is the solution and higher is the [H + ] ions Thus, solution P (pH = 1) has higher [H + ] ions than solution R (pH = 3). (b) Higher the pH of the solution, more basic is the solution and higher is the [OH - ] ions Thus, solution Q (pH = 9) has lower [OH - ] ions than solution S (pH = l3). (c) Solution P (pH = 1) is acidic which turns blue litmus solution red whereas solution Q (pH = 9) is basic which turns red litmus solution blue. (d) Solution P (pH = 1) is highly acidic while solution S (pH = l3) is highly basic and solution Q (pH = 9) is weakly basic.

${ (i) }(\mathrm{b}): \mathrm{Na}_{2} \mathrm{CO}_{3}+\mathrm{H}_{2} \mathrm{O}+\mathrm{CO}_{2} \longrightarrow 2 \mathrm{NaHCO}_{3}$ (ii) (b) : $\mathrm{NaHCO}_{3}+\mathrm{CH}_{3} \mathrm{COOH} \longrightarrow \mathrm{CH}_{3} \mathrm{COONa}$ $+\mathrm{CO}_{2} \uparrow+\mathrm{H}_{2} \mathrm{O}$ Carbon dioxide gas is evolved which turns limewater milky. It extinguishes a burning splinter since it is not a supporter of combustion. It dissolves in sodium hydroxide solution and it is an odourless gas. ${ (iii) }(\mathrm{c}): 2 \mathrm{NaHCO}_{3} \stackrel{\text { Heat }}{\longrightarrow} \mathrm{Na}_{2} \mathrm{CO}_{3}+\mathrm{H}_{2} \mathrm{O}+\mathrm{CO}_{2}$ NaHCO 3 is soluble in water. ${ (iv) }(\mathbf{b}): \mathrm{NaHCO}_{3}+\mathrm{CH}_{3} \mathrm{COOH} \longrightarrow$ $\mathrm{CH}_{3} \mathrm{COONa}+\mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O}$ (v) (c): It is not used in manufacture of soap .

(i) (d) (Ii) (b): '2' is an ionic compound ${ (iii) }(\mathrm{a}): \mathrm{Mg} \longrightarrow \mathrm{Mg}^{2+}+2 e^{-}$ $\mathrm{Cl}+e^{-} \longrightarrow \mathrm{Cl}^{-}$ $\mathrm{Mg}^{2+}+2 \mathrm{Cl}^{-} \longrightarrow \mathrm{MgCl}_{2}$ 2,8,2 2,8 2,8,7 2,8,8 $(\text { iv })(\mathrm{d}): \mathrm{Na} \longrightarrow \mathrm{Na}^{+}+e^{-}$ 2,8,1 2,8 (v) (c): (a) and (d) represent electronegative elements and (b) represents a noble gas.

(i) (c) : Molecular formula of (Q) is CSH1Sas it has two carbon atoms less than (P). (ii) (c): Compounds (P), (Q) and (R) are alkanes having general formula C n H 2n+2 . (iii) (a): Molecular formula of (R) is C 12 H 26 as it has two carbon atoms more than (P) (iv) (b): Compound (P), (Q) and (R) belong to same homologous series so they have different physical properties but similar chemical properties. They have same general formula C n H 2n+2 .They . differ by 2 carbon atoms and 4 hydrogen atoms. (v) (a)

(i) (a): As the size of the atom increases down the group, electropositive character increases. (ii) (c): Li is the first element of the second period. As the size decreases in the period from left to right, therefore, Li is the largest atom in the period. (iii) (c): Al (Z = 13) : 2, 8, 3 (iv) (b): Metallic character of elements decreases from left to right and increases down the group. (v) (a): As we move from left to right along a period, the number of valence electrons increases from 1 to 8.

(i) (a): In human, cellulose is indigestible as it cannot be broken into smaller molecules due to absence of cellulase enzyme. (ii) (b): Finger-like projections that come out from mucosa of intestine form villi. Cells lining the villi produce numerous microscopic projections called microvilli giving a brush border appearance which increase the surface area for absorption enormously. Villi has a good supply of capillaries and a large lymph vessel for absorption of nutrients. If the inner lining of the small intestine will be smooth, the surface for absorption will be reduced. (iii) (a) (iv) (c) (v) (b)

(i) (c): A- Artery: Carries blood from heart to different body parts. It is thick-walled and elastic. It acts as a "pressure reservoir" for maintaining the blood flow. B - Capillary : Nutrients, hormones, gases, etc. can diffuse into tissue cells through capillaries and vice versa. It is thin-walled, and only one cell layer thick resting on basement membrane. C - Vein: Brings blood from different body parts to the heart. It is thin-walled and act as low-resistance conduct for blood flow. D - Pulmonary vein: Two pulmonary veins from each lung transport the oxygenated blood to the left atrium. (ii) (d): In amphibians, the left atrium receives oxygenated blood from the gills/lungs/skin and the right atrium gets the deoxygenated blood from other body parts. However, they get mixed up in the single ventricle which pumps out mixed blood i.e., incomplete double circulation (iii) (d): Whale is a mammal and in mammals, two separate circulatory pathways are found - systemic circulation and pulmonary circulation. Oxygenated and deoxygenated bloods received by the left and right atria respectively pass on to the left and right ventricles. Thus, oxygenated and deoxygenated bloods are not mixed. This is referred to as double circulation. (iv) (a) (v) (c): Pulmonary circulation is the movement of blood between heart and lungs. During this pathway deoxygenated blood entering the right atrium, moves into the right ventricle. From here it moves through the pulmonary arch into the lungs for oxygenation. Then from lungs the oxygenated blood moves into the left atrium through pulmonary veins.

(i) (b): The tiny spores of bread mould (Rhizopus) are always present in air. On coming in contact with moist surface of bread slice they settle on it and germinate to form new fungal hyphae which first look like white cottony mass and later turns black. (ii) (a): Mucor (fungus) reproduces asexually through spore formation. (iii) (d) (iv) (c) : Bacteria produce endospore which is a dormant and tough structure that enables bacteria to remain dormant for extended periods under unfavorable conditions. (v) (d)

(i) (a) : Characters studied by Mendel are as follows:

(i) (a): The angle between the two refracting surfaces of a prism is called angle of prism. (ii) (b): The angle between the incident ray and the emergent ray is called angle of deviation. (iii) (d): As the ray of light enters from rarer medium (air) to denser medium (glass), the angle of incidence is more than angle of refraction. (iv) (c): More be the refractive index, more be the angle of deviation and it also depends on the refractive index of prism. (v) (c): The refraction of light takes place through rectangular surfaces.

(i) (c): No two magnetic field lines are found to cross each other. If two field lines crossed each other, it would mean that at the point of intersection, the compass needle would point in two directions at the same time, which is not possible. (ii) (d): The magnetic field and hence the magnetic line of force exist in all the planes all around the magnet. (iii) (d): The relative strength of the magnetic field is shown by the degree of closeness of the field lines and the direction of the magnetic field is obtained by tangent to the field lines at the point of intersect. (iv) (d): The magnetic field lines due to a bar magnet are closed continuous curves directed from N to S outside the magnet and directed from S to N inside the magnet. Hence option (d) is correct. v) (d): Inside a bar magnet, the direction of field lines is from south pole to north pole

(i) (a): Due to bio-rnagnification, the concentration of DDT will always be less in zooplanktons than large fish (ii) (c) (iii) (b) : Due to bio-rnagnification the nonbio-degradable chemicals such as DDT accumulate and go on concentrating at each trophic level. (iv) (d) : Higher amounts of DDT disturb calcium metabolism of birds resulting in thinning of egg shells and their prematllre breaking that kills the embryos. (v) (d)

( i) (b) : In the given pie chart, gases P, Q, Rand S respectively are CO 2 , CH 4 , CFCs and N 2 O. Methane is produced by incomplete combustion of biomass. (ii) (c): Methane (gas Q) is produced by incomplete biomass combustion and incomplete decomposition mostly by anaerobic methanogens. Flooded paddy fields, marshes and cattles are the major source of this gas. (iii) (c) : CO 2 is the principal greenhouse gas that helps to keep the earth warm. (iv) (d) (v) (c)

(i) (b): 1% of solar radiation is captured by plants. Sun is the ultimate source of all energy. (ii) (d) (iii) (d) (iv) (d): The given pyramid is pyramid of energy that shows the two basic laws of thermodynamics. (v) (c): Light energy from the sun is converted to chemical energy in producers via photosynthesis. This chemical energy is then transferred to primary consumer, then subsequently to secondary consumer via feeding.

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Heredity and Evolution Case Study Based Questions Class 10

Students who are studying in CBSE class 10 board, need to get the knowledge about the Heredity and Evolution Case Study Based Questions. Case based questions are generally based on the seen passages from the chapter Heredity and Evolution. Through solving the case based questions, students can understand each and every concept.

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Heredity and Evolution Case Study Based Questions with Solutions

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Case studies covers all the concepts which are included in the Heredity and Evolution

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Identify the questions and give the answers according to the case given.
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Answer according to the options given below the questions provided in the Heredity and Evolution Case Study Based Questions.

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Home » Study Material » Class 10 - Important Questions » Science » Chapter 9 - Heredity and Evolution

CBSE Class 10 Science - Chapter 9 - Heredity and Evolution

Important questions and answers (pages 21-25).

Following are the important questions of the chapter "Heredity and Evolution".

Pages 1-20 Pages 21-25

Important Questions of CBSE class 10 Science

Extra Questions for Class 10 Science Chapter 9 Heredity And Evolution

Get extra questions for Class 10 Science Chapter 9 Heredity And Evolution with PDF. Our subject expert prepared these solutions as per the latest NCERT textbook. These extra questions will be helpful to revise the important topics and concepts. You can easily download all the questions and answers in PDF format from our app.

Heredity And Evolution Class 10 Science Extra Questions with Answers

Question 1: What is a gene?

Answer: Gene is the unit of inheritance. Gene is the part of a chromosome which controls the appearance of a set of hereditary characteristics.

Question 2: What is meant by analogous organs? Taking a suitable example, explain how they support the theory of Organic Evolution.

Answer: Analogous organs are those organs which I have different basic structural design and developmental origin but have similar appearance and perform similar functions.

Example: The wings of birds and bats look similar but have different design in their structure. They have a common function of flying but their origins are not common. So, birds and bats are not closely related.

Question 3: What is a sex chromosome?

Answer: Sex chromosome is a chromosome that operates in the sex-determining mechanism of a species. Many animals have two different types of sex chromosomes. For example, in human there is a large X chromosome and a much smaller Y chromosome.

Question 4: “The sex of the children is determined by what they inherit from their father and not their mother.” Justify.

Answer: It is because a child who inherits an X chromosome from her father will be a girl and one who inherits a Y chromosome from his father will be a boy. But all children inherit a X chromosome from their mother regardless of whether they are boys or girls.

Question 5: Define variation in relation to a species. Why is variation beneficial to the species?

Answer: Variation refers to the differences in the characters or traits among the individuals of a species. Variations are beneficial to the species because:

They enable the organisms to adapt themselves in changing environment.
Variations form the basis of heredity.
They form the raw materials for evolution and development of new species.

Question 6: Describe briefly four ways in which individuals with a particular trait may increase in a population.

Answer: The four ways in which individuals with a particular trait may increase in a population are as follows:

Sexual reproduction results into variations.
The individuals with special traits survive the attack of their predators and multiply while the other
will perish.
Genetic drift provides diversity without any adaptation.
Variations in the species may lead to increased survival of the individuals.

Question 7: What are fossils? What do they tell us about the process of evolution?

Answer: The remains of dead plants and animals which were buried under the rocks millions of years ago are called fossils.

Fossils tell us about the process of evolution. The fossils of different organisms have some features similar to one species while some features are similar to the other species. In this way, they show the link between two species. They tell us that one species evolves from the other.

Question 8: Give one example each of characters that are inherited and the ones that are acquired in humans. Mention the difference between the inherited and the acquired characters.

Answer: Eye colour or hair colour of a person is an example of inherited character whereas, body weight is an example of acquired character.

The basic difference between inherited and acquired character is that inherited character is passed on from parent to offspring and acquired characters are acquired by an individual during his lifetime depending upon his lifestyle.

Question 9: How is the equal genetic contribution of male and female parents ensured in the progeny?

Answer: During sexual reproduction, a female gamete or egg cell fuses with a male gamete or sperm cell which are haploid to form zygote. Zygote is diploid which contains 23 chromosomes from mother and 23 from father. In this way, an equal genetic contribution of male and female parents is ensured in the progeny.

Question 10: What evidence do we have for the origin of life from inanimate matter?

Answer: Stanley L. Miller and Harold C. Urey provided evidence regarding origin of life from inanimate matter. They assembled an atmosphere similar to that existed on early earth. The atmosphere had molecules like ammonia, methane and hydrogen sulphide, but no oxygen and kept over water at temperature just below 100°C. Sparks were passed through the mixture of gases. At the end of a week, 15% carbon from methane had been converted to simple compounds of carbon like amino acids which make-up protein molecules. So, life arose afresh on earth.

Question 12: Define ‘evolution’. Describe Darwin’s theory of evolution. [All India]

Answer: Evolution is the sequence of gradual changes which take place in the primitive organisms over millions of years and new species are produced. Since, the evolution is of the living organisms, so it is called ‘Organic Evolution’.

Darwin’s theory of Evolution: Charles Robert Darwin gave the theory of evolution in his famous book, ‘The Origin of Species’. The theory of evolution proposed by Darwin is known as ‘The Theory of Natural Selection’. It is also called ‘Darwinism’.

According to Darwin’s theory of evolution:

There is natural variation within any population and some individuals have more favourable variations than others.
Population remains fairly constant even though all species produce a large number of off springs.
This is due to ‘competition’ or struggle for existence between same and different species.
The struggle for survival within population eliminates the unfit individuals and those with ‘favourable variations’ survive and pass on these variations to their progeny to continue. This is called natural selection.
The favourable variations are accumulated over a long time period leading to the origin of a new species.

Question 13: Distinguish between acquired and inherited traits by giving one example of each. Why are traits acquired during the lifetime of an individual not inherited?

Answer: Acquired trait is a particular characteristic that is developed during the lifetime of an individual. Such characteristics are not genetically controlled and cannot be passed on to the next generation. Example: Loss of weight due to starvation.

Inherited trait is the transmission of particular characteristics from parents to their off springs, generation to generation. Such traits are genetically determined characteristic that distinguishes a person. Example: Colour of skin.

The acquired traits cannot change the DNA of the germ cells. Therefore, the acquired traits cannot be inherited over generations during the lifetime of an individual.

Question 14: The human beings who look so different from each other in terms of colour, size and looks are said to belong to the same species. Why? Justify your answer.

Answer: Human beings are said to belong to the same species because of the following reasons:

DNA studies.
Number of chromosome is same,
All have a common ancestor.
They interbreed among themselves to produce fertile young ones of their own kind.

Question 15: Explain the mechanism of sex determination in humans. Or With the help of a flow chart explain in brief how the sex of a newborn is genetically determined in human beings. Which of the two parents, the mother or the father, is responsible for determination of sex of a child?

Class 10 Chapter 9 Heredity and Evolution Extra Questions 15

Mechanism of Sex Determination in Human Beings:

In human beings, the sex of the individual is genetically determined.

Sex determination is the process by which sex of a new born individual can be determined.
Human beings have 1 unpaired sex chromosome. Sex chromosome of male is XY and of female is XX.
Sex of a child depends on what happens at fertilisation.

Thus, father is responsible for the determination of the sex of a child.

Question 16: With the help of suitable examples explain natural selection.

Answer: Let us assume that there exist a group of red beetles in some green bushes. Due to variation during sexual reproduction one green beetle evolved among them. This green beetle can pass the colour to its progeny which are green beetles.

Crows cannot see green beetles in green bushes and therefore, cannot eat them. The progeny of green beetles are not eaten while the progeny of red beetles continued to be eaten. As a result there are more and more green beetles in the beetle population. The progeny of green beetles increase due to natural selection which gives survival advantage.

Question 17: Explain the terms: (i) Speciation (ii) Natural selection

Answer: (i) Speciation is the evolution of reproductive isolation among once-interbreeding populations, i.e. the development of one or more species from an existing species.

(ii) Natural selection is the process, according to Darwin, which brings about the evolution of new species of animals and plants.

Question 18: Explain with examples how the following are evidences in favour of evolution in organisms. (i) Homologous organs (ii) Analogous organs (iii) Fossils

Answer: (i) Forelimb of human and bird are homologous organs. They have same structural design and developmental origin but they have different functions and appearance. Homologous organs help us to understand that the organism has evolved from a common ancestor. The more common characteristics the two species have, the more closely they are related.

(ii) Analogous organs are those organs design and developmental origin but have similar appearance and perform similar functions.

(iii) Fossils and their study is useful in knowing about the species which are no longer alive. They provide evidence and missing links between two classes. They are helpful in forming a sequence of organisms in the pathway of evolution. Thus, fossils have an importance in deciding evolutionary relationship. Archaeopteryx is a fossil bird. It had feathers, fused bones and beak which are exclusively bird structures. It also had some features which are found in reptiles, e.g. teeth in jaw, claws on free fingers and a long tail. This fossil provides a clue that birds have evolved from reptiles.

Question 19: Give an example of body characteristics used to determine how close two species are in terms of evolution and explain it.

Answer: Homologous organs help to identify the relationship between organisms. These characteristics in different organisms would be similar because they have inherited from a common ancestor.

For example, forelimbs of human and wings of birds show closeness between the two species because the organs have similar basic structural design of limbs though it has been modified to perform different functions.

Question 20: What are homologous organs? Can the wing of a butterfly and the wing of a bat be regarded as homologous? Why?

Answer: Homologous organs are those organs which have the same basic structural design and developmental origin but have different functions and appearance.

Example: The forelimb of a frog, a lizard, a bird and a man seem to be built from the same basic design of bones, but they perform different functions.

Class 10 Chapter 9 Heredity and Evolution Extra Questions 20

No, the wing of a butterfly and the wing of a bat cannot be considered homologous organs because they have a common function for flying but their origin and structure are not common. So, they are analogous organs.

Question 21: What is meant by the term speciation? List four factors which could lead to speciation.

Answer: Speciation is the evolution of reproductive isolation among once interbreeding population.

Factors which can lead to speciation are:

Genetic drift: Over generations, genetic drift may accumulate which leads to speciation.
Natural selection: Natural selection may work differently in different location which may give rise to speciation.
Severe DNA change.
A variation may occur which does not allow sexual act between two groups.

Question 22: Distinguish between homologous organs and analogous organs. In which category; would you place wings of a bird and wings of a bat? Justify your answer giving a suitable reason.

Wings of a bird and wings of a bat are analogous organs as they have different basic structural design but have similar appearance and perform similar functions.

Question 23: A blue colour flower plant denoted by BB is cross breed with that of white colour flower plant denoted by bb. (a) State the colour of flower you would expect in their F1 generation plants. (b) What must be the percentage of white flower plants in F2 generation if flowers of F1 plants are self-pollinated? (c) State the expected ratio of the genotypes BB and Bb in the F2 progeny. [Delhi]

Answer:

Class 10 Chapter 9 Heredity and Evolution Extra Questions 23

Question 24: Define the term ‘evolution’. “Evolution cannot be equated with progress”. Justify this statement.

Answer: Evolution is the sequence of gradual change which takes place in primitive organisms over millions of years and new organisms are formed. Evolution cannot be equated to progress from lower forms to higher forms. It seems to have given rise to more complex body designs even while the simpler body designs continue to flourish. For example, human beings have not evolved from chimpanzees, but both have common ancestor.

Question 25: If we cross pure-bred tall (dominant) pea plant with pure-bred dwarf (recessive) pea plant we will get pea plants of F1 generation. If we now self-cross the pea plant of F2 generation, then we obtain pea plants of F2 generation. (a) What do the plants of F2 generation look like? (b) State the ratio of tall plants to dwarf plants in F2 generation. (c) State the type of plants not found in F2 generation but appeared in F2 generation, mentioning the reason for the same.

Answer: (a) All plants of F1 generation will be tall plants. (b) 3:1 (c) Dwarf trait is recessive trait which was not expressed in the F1 generation, the recessive trait gets expressed in the F2 generation after self-pollination.

Question 26: How are fossils formed? Describe, in brief, two methods of determining the age of fossils.

Answer: When organisms die, their bodies decompose due to action of microorganisms. However, sometime the body or at least some parts of the body may be in such an environment that does not let it decompose completely. All such preserved traces of living organisms are called fossils. The age of fossils can be estimated by the following two methods:

If we dig into the earth and start finding fossils, it can be assumed that the fossils closer to the surface are more recent to those found in deeper layers.
By detecting the ratios of different isotopes of the same element in the fossil material.

Question 27: State the meaning of inherited traits and acquired traits. Which of the two is not passed on to the next generation? Explain with the help of an example.

Answer: Inherited traits are the characteristics transmitted from parents to their offspring. Acquired traits are characteristics which are developed during the lifetime of an individual. Acquired traits are not passed on to the next generation. For example, if we breed a group of mice, all their progeny will have tails. Now, if the tails of these mice are removed by surgery and allowed to breed, the next generation mice will also have tails. If these tails are also removed and allowed to breed, the progeny of mice will again have tails. Removal of tail by surgery is an acquired trait and do not change the genes of germ cells and hence, are not passed on to the next generation.

Question 28: “An individual cannot pass on to its progeny the experiences of its lifetime.” Justify the statement with the help of an example and also give reason for the same.

Answer: Experience achieved during the lifetime of an individual does not make any change in the gene of the individual.

For example: if a person reads a book on birds, the knowledge he earns by reading the book does not make any change in the gene, hence, this knowledge will not get automatically transmitted to his next generation. Such a trait is called acquired trait.

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Case Study Questions Class 10 Science Chapter 9 Heredity and Evolution
Here, we have provided case-based/passage-based questions for Class 10 Science Chapter 9 Heredity and Evolution. Case Study/Passage Based Questions. Question 1: Pea plants can have smooth seeds or wrinkled seeds. One of the phenotypes is completely dominant over the other.
Case Study Questions Class 10 Science Heredity and Evolution
CBSE Case Study Questions Class 10 Science Heredity and Evolution. A scientist cross pure-bred tall (dominant) pea plant with pure-bred dwarf (recessive) pea plant he will get pea plants of F1 generation. If now self-cross the pea plant of F2 generation is done, then we obtain pea plants of F2 generation. [KVS Raipur 2021-22]
Case Study and Passage Based Questions for Class 10 Science Chapter 9
In CBSE Class 10 Science Paper, Students will have to answer some questions based on Assertion and Reason. There will be a few questions based on case studies and passage based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked. Here, we have provided … Continue reading Case Study and Passage Based Questions for Class 10 Science Chapter 9 ...
Case Study Chapter 9 Heredity And Evolution
Please refer to Chapter 9 Heredity And Evolution Case Study Questions with answers provided below. We have provided Case Study Questions for Class 10 Science for all chapters as per CBSE, NCERT and KVS examination guidelines. These case based questions are expected to come in your exams this year. Please practise these case study based Class 10 ...
CBSE Class 10 Science Chapter Wise Important Case Study Questions
The Chapter wise Important case study based questions with their solved answers in CBSE Class 10 Science can be accessed from the table below: CBSE Class 10 Science Chapter 1 Chemical Reactions ...
Class 10 Science: Case Study Chapter 9 Heredity and Evolution PDF
Case Study Chapter 9 Heredity and Evolution. Here, we have provided case-based/passage-based questions for Class 10 Science Chapter 9 Heredity and Evolution. Case Study/Passage Based Questions. Question 1: Pea plants can have smooth seeds or wrinkled seeds. One of the phenotypes is completely dominant over the other.
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Case Study Questions Class 10 Science. In board exams, students will find the questions based on assertion and reasoning. Also, there will be a few questions based on case studies. In that, a paragraph will be given, and then the MCQ questions based on it will be asked. Case Study Questions for Chapter 1 Chemical Reactions and Equations.
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Class 10 Science Sample Papers with case study questions are available in the myCBSEguide App. There are 4 such questions (Q.No.17 to 20) in the CBSE model question paper. If you analyze the format, you will find that the MCQs are very easy to answer. So, we suggest you, read the given paragraph carefully and then start answering the questions.
Class 10 Science Chapter 9 Case Based Questions
Full syllabus notes, lecture and questions for Class 10 Science Chapter 9 Case Based Questions - Light Reflection and Refraction ... Students of Class 10 can study Case Based Type Practice Questions: Light- Reflection & Refraction alongwith tests & analysis from the EduRev app, which will help them while preparing for their exam. ...
NCERT Solutions for Class 10 Science Chapter 9 Heredity and Evolution
Chapter 9 - Heredity and Evolution are expected to have between 1 to 3 marks based on the yearly trends. In 2018, however, only 1 question was asked (regarding Laws of Inheritance) in the Class 10 Science exam. But it would be wise to learn all the relevant concepts in order to avoid any unpleasant surprises.
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Case Study Class 10 Science: Here, you will get class 10 Science case study questions and answers pdf at free of cost. Along with you can also download case study questions class 10 Science chapter wise for getting higher marks in board examinations. Sharda University Admission - 100% Scholarship upto - Limited Time Offer - Apply Now ...
Important Questions for CBSE Class 10 Science Chapter 9
Study Important Questions for Class 10 Science Chapter 9 - Heredity and Evolution. Very Short Answer Questions (1 Mark) 1. Select the group which shares the maximum number of common characters-. Two genera of two families. Two species of a genus. Two genera of a family. Two individuals of a species.
Case Study Question for Class 10 Science Ch. 1, 2, 4, 6, 7, 8, 9, 10
Case Study Question Class 10 Science for CBSE Board: ... Case Based Questions Class 10 Science Chapter-wise: Chapter 1. Chemical reactions and equations: Chapter 9: Heredity and Evolution. Chapter 2. Acids, bases and salt: Chapter 10: Light Reflection and Refraction. Chapter 3. Metals and Non-metals:
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CBSE 10th Standard Science Subject Heredity and Evolution Case Study Questions With Solution 2021. Sex determination is the method by which distinction between males and females is established in a species. The sex of an individual is determined by specific chromosomes. These chromosomes are called sex chromosomes or allosomes.
CBSE Class 10th
For Science subjects, there would be 5 case-based sub-parts questions, wherein a student has to attempt 4 sub-part questions. Chapters. Download. 1. Chemical Reactions & Equations. Click Here. 2. Acids, Bases & Salts. Click Here.
NCERT Solutions for Class 10 Science Chapter 9 Heredity and Evolution
NCERT Solutions for Class 12 Business Studies; NCERT Solutions for Class 12 Accountancy; ... NCERT Solutions for Class 10 Science Chapter 9 Intext Questions. Page Number: 143. Question 1. ... e.g., take the case of free ear lobe and attached ear lobe. Most of the other variations not only give survival advantage to an individual but also ...
NCERT Solutions for Class 10 Science Chapter 9 Heredity and Evolution
These Class 10 Science NCERT Solutions are prepared as per the accordance of latest CBSE guidelines so you can score maximum marks. Chapter 9 of NCERT Solutions Class 10 Science consists of 12 exercise questions and 17 in-text questions. It will give good experience and provide opportunities to learn new things. Topics in the Chapter.
CBSE 10th Science Case Study Questions
CBSE 10th Standard Science Subject Case Study Questions. Redox reactions are those reactions in which oxidation and reduction occur Simultaneously. A redox reaction is made up of two half reactions. In the first half reaction, oxidation takes place and in second half reaction, reduction occurs. Oxidation is a process in which a substance loses ...
Heredity and Evolution Case Study Based Questions Class 10
These tips can help students to score good marks in CBSE Class 10 Science. Generally, the case based questions are in the form of Multiple Choice Questions (MCQs). Students should start solving the case based questions through reading the given passage. Identify the questions and give the answers according to the case given.
CBSE Class 10 Science Case Study Questions
Physics Chapters for Case Study Questions. Light - Reflection and Refraction. The Human Eye and The Colourful World. Electricity. Magnetic Effects of Electric Current. TopperLearning provides a complete collection of case studies for CBSE Class 10 Science students. Improve your understanding of biological concepts and develop problem-solving ...
CBSE Class 10 Science
Important Questions and Answers (Pages 21-25) Following are the important questions of the chapter "Heredity and Evolution". Pages 1-20 Pages 21-25. Pages 1-20 Pages 21-25. Find out the important questions and answers for CBSE Class 10 Science, Chapter 9 - Heredity and Evolution. Get the edge you need to excel in this crucial topic. (Pages 21-25)
Extra Questions for Class 10 Science Chapter 9 Heredity ...
Question 28: "An individual cannot pass on to its progeny the experiences of its lifetime.". Justify the statement with the help of an example and also give reason for the same. Answer: Experience achieved during the lifetime of an individual does not make any change in the gene of the individual.

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