formulate a hypothesis for the frequency of tongue rollers as compared to non rollers

Life Science Grade 12 Practical Investigation 2021 Memo

Table of Contents

Investigation 1: Surveying Human Characteristics Task Investigation

Conduct a survey of the occurrence/frequency of dominant and recessive phenotypes for each of three traits/ characteristics (as shown in the pictures below) among the learners in your school.

• This task must be done individually.
• This practical must be completed at school.

List any FOUR planning steps for this investigation:

Answers from the memo:

• Seek permission to conduct the investigation.
• Decide how the learners are to be selected for your sample.
• Identify the 20 learners who will form a part of the sample.
• Arrange a date/time/venue for surveying the different characteristics.
• Design a table for recording information.
• Study the different phenotypes for each characteristic in order to correctly identify them.

Formulate a hypothesis for the frequency of tongue-rollers as compared to non-rollers in your school:

• There are more learners in the school that are tongue rollers than non-rollers
• There are more learners in the school that are non-rollers than tongue rollers
• The number of learners in the school that are tongue rollers is equal to the number ofnon-rollers

Practical Task 2 – Simulating natural selection

Simulate ‘natural selection’ using a paper model.

• This task must be done in pairs but the questions must be answered individually.

Background information A simulation allows one to demonstrate something that might sometimes be dangerous or that might sometimes require a lot of time, quickly and in a simple and safe way, using models. The different parts that comprise the paper model in this task represent different components in nature. The sheet of newspaper and the sheet of white paper represent two different environmental conditions. The circles cut from white paper and from newspaper represent the different appearances/phenotypes of different individuals of the same species.

Downloadable Tasks Memo

Complete Memo with all questions and answers can be found on the pdf document below:

View all # Life-Sciences-Grade12 Study Resources

We have compiled great resources for Life Sciences Grade 12 students in one place. Find all Question Papers, Notes, Previous Tests, Annual Teaching Plans, and CAPS Documents.

More Questions and Answers from Previous Question Papers

What is more useful for a grade 12 learner than actual exam questions and answers from previous question papers? We have collected 100s of grade 12 questions and answers for Grade 12 subjects from all South African Provinces: Limpopo, Gauteng, Free State, North West, Eastern Cape, Northern Cape, KZN, Western Cape, and Mpumalanga. The questions and answers are for Term 1, Term 2, Term 3, and Term 4, for the following years: 2023, 2022, 2021, 2020, 2019, and 2018. Take a look at the links below , or search for more.

LIFE SCIENCES SCHOOL BASED ASSESSMENT EXEMPLARS - CAPS GRADE 12 TEACHER'S GUIDE

LIFE SCIENCES SCHOOL BASED ASSESSMENT EXEMPLARS - CAPS GRADE 12 TEACHER GUIDE

1. Introduction  Assessment is a continuous planned process of identifying, gathering and interpreting information about the performance  of learners, using various forms of assessment. It involves four steps: generating and collecting evidence of achievement,  evaluating this evidence, recording the findings and using this information to understand and assist in the learners’  development to improve the process of learning and teaching. Assessment should be both informal (Assessment for  Learning) and formal (Assessment of Learning). In both cases regular feedback should be provided to learners to  enhance the learning experience.  School-based assessment (SBA) forms part of the formal assessment component. It is a purposive collection of learners’  work that tells the story of the learners’ efforts, progress or achievement in attaining knowledge (content, concepts and  skills) in the subject. The advantages of school-based assessment can be summarised as follows: 

• It provides a more balanced and trustworthy assessment system, increasing the range and diversity of assessment  tasks. 
• It improves the reliability of assessment because judgements are based on many observations of the learner over  an extended period of time. 
• It empowers teachers to become part of the assessment process and enhances collaboration and sharing of  expertise within and across schools. 
• It has a professional development function, building up practical skills in teacher assessment which can then be  transferred to other areas of the curriculum. 

School-based assessment forms part of a year-long formal Programme of Assessment in each grade and subject. The  assessment tasks should be carefully designed to cover the content of the subject as well as the range of skills and  cognitive levels that have been identified in specific aims. Tests, practical tasks, assignments and projects make up the  SBA component in Life Sciences.  Teachers should ensure learners understand the assessment criteria and have extensive experience using it for self- and  peer assessment in informal situations before conducting a planned formal assessment activity. Teachers should also  have used these criteria for informal assessment and teaching purposes before they conduct any formal assessment so  that learners are familiar with the criteria and the assessment process. 

2. Aims of the project  Through this publication it is envisaged that TEACHER capacity will be increased in respect of each of the following: 

• Differentiating among the nature of the different types of assessment tasks (assignments, projects, practical  tasks, tests and examinations)  
• Developing assessment tasks that are balanced in terms of cognitive levels, topics and skills 
• Is appropriate to the task 
• Clearly shows mark allocation and distribution 
• Includes alternative answers 
• Developing tasks that contain a variety of question types 

Through this publication it is also envisaged that LEARNERS will benefit by: 

• Developing an understanding of the differences amongst the nature of the various types of assessment tasks 
• Being exposed to assessment tasks that are of the same standard as those that they are exposed to during the  course of the year

3. Programme of formal assessment in Life Sciences 

• This includes all assessment tasks that make up the formal programme of assessment for the year.
• Formal assessment tasks are marked and recorded by the teacher for promotion and certification purposes. 
• All tasks must be subjected to pre- and post-moderation to ensure that appropriate standards are maintained.
• The table that follows shows the number and types of assessment tasks required in the Grade 12 year. 

NOTE: The SBA mark must be converted to 25% and the external examination counts 75% of the final mark. A description of the requirements for each of the different types of assessment tasks follows below.

3.1 Practical tasks  When designing the practical tasks, the Life Sciences teacher must ensure that: 

• Follow instructions 
• Handle equipment or apparatus
• Make observations 
• Record information or data 
• Measure accurately 
• Interpret information
• Design/Plan an investigation
• At least ONE of the practical tasks includes manipulation of apparatus and/or collection of data. 
• Any ONE practical task assesses at least 3 of the 7 skills and must include skill 6 and/or 7. 
• 20–40 marks are allocated to a practical task.  

3.2 Research Project  At least ONE of the tasks across Grades 10–12 must be a research project.  When designing the research project, the Life Sciences teacher must ensure that it: 

• Is a long-term task (at least 3 weeks of non-contact time) 
• Has a maximum mark of 100  
• covers Specific Aims 1, 2 and 3 
• Is recorded in Term 3 even if it is given and assessed in Term 1 or Term 2 
• Is an investigative task 
• Focuses on accessing knowledge through literature research as well as through primary sources such as people 
• Formulating investigative questions and hypotheses 
• Gathering information from a variety of sources
• Manipulating and processing information
• Analysing information
• Identifying patterns 
• Evaluating data
• Drawing valid conclusions
• Communicating findings

3.3 Assignment At least ONE of the tasks across Grades 10–12 must be an assignment.  When designing an assignment, the Life Sciences teacher must ensure that it: 

• Is a short-term task (1½-2 hours under controlled conditions) 
• Covers Specific Aims 1, 2 and 3 
• Is completed at school and not at home 
• Covers a variety of topics 
• Analysing and interpreting data
• Making drawings
• Plotting graphs
• Drawing tables
• Performing calculations
• Justifying conclusions 

3.4 Tests and Examinations  When designing the tests as well as the mid-year and trial examinations, the Life Sciences teacher must ensure that: 

• The test is a minimum of 50 marks. 
• The test in Term 1 covers all work done in that term. 
• The tests in Term 2 and Term 3 cover at least half of the work covered in the respective terms. 
• The mid-year examinations cover work completed in Term 1 and Term 2. 
• The trial examinations cover all work completed in Terms 1, 2 and 3, and must include the section on ‘Human  Impact’ from Grade 11. 
• Mainly Specific Aims 1 and 3 are covered. 
• Specific Aim 2 (knowledge and understanding of investigations and practical work) is also included, but in a  smaller proportion compared to Specific Aims 1 and 3. 
• Tests and examinations are balanced in terms of cognitive levels and topic weightings. In this regard weighting  grids must be used. 
• Tests and examinations are analysed diagnostically and appropriate remedial and intervention strategies are  instituted. 
• Tests and examinations follow the external examination in its design, rigour and format.

4. Scope of the project   This publication includes the following: 

• Requirements for the Grade 12 Programme of Assessment for the Life Sciences CAPS curriculum
• A description of the various types of assessment tasks (assignment, project, practical task and test) 
• Exemplar assessment tasks (assignment, practical task and test) 
• Marking Guidelines for each assessment task 

The following exemplars together with their marking guidelines have been included in this publication: 

5. Quality assurance process followed  A team of experts comprised of teachers and subject advisors from provinces was appointed by the DBE to develop  and compile assessment tasks. They were required to extract excellent examples of learner tasks from their respective  schools and districts. The panel of experts spent a period of four days at the DBE, developing tasks based on guidelines  and policies. Moderation and quality assurance of the tasks were undertaken by national and provincial examiners and  moderators. The assessment tasks were further refined by the national internal moderators to ensure that they were in  line with the CAPS document.

6. Assessment tasks  6.1 Practical Task 1 – Surveying human characteristics 

Task  Conduct a survey of the occurrence/frequency of dominant and recessive phenotypes for each of three traits/ characteristics (as shown in the pictures below) among the learners in your school. 

• This task must be done individually. 
• This practical must be completed at school. 
• Select 20 learners that will form part of your sample. 
• For every learner selected, record the phenotype for each characteristic. 
• Record the information for each learner in a table. At the end of the table, include the percentage of learners  displaying each phenotype for each of the three characteristics. 
• Answer the questions set. 
• List any FOUR planning steps for this investigation.  (4)
• In terms of the investigation about the type of earlobe (free or attached), name the following: 2.1 The dependent variable  (1) 2.2 The independent variable  (1)
• Formulate a hypothesis for the frequency of tongue-rollers as compared to non-rollers in your school.    (3)
• Construct a table to show the results obtained in this investigation.   (4)
• According to the results obtained, would you accept or reject the hypothesis formulated in QUESTION 3?  (1)
• State TWO ways in which you could make the results of this investigation more reliable. (2)
• Using the same system of axes, draw a bar graph to represent the percentage of learners displaying each phenotype for each of the three characteristics.  (8)
• Use the symbols R (tongue-roller) and r (non-roller) to represent the phenotypes and genotypes of  offspring resulting from a cross between two heterozygous individuals.   (6) 

6.2 Practical Task 2 – Simulating natural selection   

Task  Simulate ‘natural selection’ using a paper model. 

• This task must be done in pairs but the questions must be answered individually. 

Background information  A simulation allows one to demonstrate something that might sometimes be dangerous or that might sometimes require  a lot of time, quickly and in a simple and safe way, using models.   The different parts that comprise the paper model in this task represent different components in nature. The sheet of  newspaper and the sheet of white paper represent two different environmental conditions. The circles cut from white  paper and from newspaper represent the different appearances/phenotypes of different individuals of the same species. 

Aim  You are required to investigate the survival of the organisms with the two different phenotypes under different  environmental conditions.   Materials required 

• A sheet of white paper (preferably A3 size) to use as background 
• A sheet of newspaper (cut to A3 size) to use as background 
• Forceps/tweezers 
• Clock with a second hand/stopwatch 
• 30 x 2 cm diameter circles cut from another sheet of newspaper 
• 30 x 2 cm diameter circles cut from another sheet of white paper 
• Place the sheet of white paper on the table. 
• Spread 30 white paper circles and 30 newspaper circles randomly over the surface of the white paper. 
• Ask your partner to use a pair of forceps/tweezers to pick up as many circles as he/she can in a period of 15  seconds.
• Count the number of each type of circle that has been picked up. Record this in the table provided.
• Now repeat steps 1–4 using the sheet of newspaper instead of the sheet of white paper.

Question 1. 

• Formulate a hypothesis for the above investigation when using the sheet of white paper as  background.  (3)
• For this investigation, name: 2.1 The dependent variable  (1) 2.2 The independent variable  (1) 2.3 Any TWO fixed variables  (2)

Draw a bar graph on the same system of axes to represent the results of your investigation. (8) 

Explain the difference in results obtained for the two types of circles when using the sheet of white  paper. (3) 

State ONE way in which you could improve the reliability of the results.  (1) 

• State a conclusion for the above investigation when the newspaper was used as a background. (3)
• Based on the results obtained, will you accept or reject the hypothesis you formulated in QUESTION  1?   (1)

6.3 Assignment 1 – Response to the environment 

Instructions and information  

• Answer ALL questions.
• Number the answers correctly according to the numbering system used in this question paper.
• Draw diagrams and flow charts ONLY when requested to do so.
• This assignment is to be done under controlled conditions and must be handed in at the end of the session. 

NOTE: If it is not possible to schedule a single 90-minute session for this assignment, then SECTION A can be  done on one day in a 45-minute session and SECTION B the following day in another 45-minute session. 

________________________________________________________________________ 

SECTION A  QUESTION 1  An investigation was conducted to study apical dominance in bean plants. Four groups of plants were used. The  diagram below illustrates the process. 

The results are shown in the table below.

1.1 For this investigation, state the: (1) 

1.1.1 Independent variable (1)  1.1.2 Dependent variable (2)  1.1.3 Any TWO fixed variables (3)  

1.2 Formulate a possible hypothesis for the above investigation. (4)   1.3 Explain the difference in results for Groups 3 and 4.  (1)  1.4 Do the results allow you to accept or reject the hypothesis you formulated in QUESTION 1.2? [12]

QUESTION 3  Read the passage below and answer the questions that follow. 

The normal plasma glucose level is 100 mg/100 ml. The glucose tolerance test was conducted for three adults and the  plasma glucose level (mg/100 ml) was recorded for two hours at 30-minute intervals. The results are shown below. 

3.1 State how the glucose tolerance response test above is used to decide if a person is suffering from  diabetes.   (2)  3.2 Adult 1 is not diabetic.  

3.2.1 Describe the changes expected in insulin secretion in Adult 1 during the period 30 minutes to  90 minutes after the glucose drink.  3.2.2 Explain your answer to QUESTION 3.2.1.   (2)  

3.3 Draw two line graphs on the same set of axes to show the glucose tolerance of Adults 1 and 2. (9)  3.4 What was the percentage increase in glucose level when the glucose was at its maximum in Adult  2? Show all working.   (3) 3.5 Write down the plasma glucose level of the three adults after two hours as a ratio in simple whole  numbers. Show all working.  (2)  3.6 Suggest, with reasons, what would happen to insulin secretion for Adult 2: 

3.6.1 If the condition was IDDM (2)  3.6.2 If the condition was NIDDM  (2) 

[24]  TOTAL SECTION A: 50

SECTION B  QUESTION 4  Read the passage and information below and answer the questions that follow. 

Two learners conducted an investigation in the following way to determine which sense organ sends the message  fastest to the brain: the eye, the ear or the skin (sight, hearing, or touch): 

• Vusi held a meter stick between his thumb and index finger just above the 100 cm mark, while Mary placed her  thumb and forefinger at the 0 mark on both sides of the stick with just the thumb touching it.
• As Vusi dropped the meter stick Mary attempted to catch it by closing her thumb and forefinger. The distance on  the meter stick that the stick fell before Mary caught it was recorded and the procedure was repeated three times. 
• They repeated the investigation to determine hearing and skin responses. For the hearing response, Mary was  blindfolded and reacted to Vusi shouting ‘DROP’ when he let go of the stick. For the skin response, Mary was  blindfolded again. Vusi tapped Mary’s free hand when he let go of the stick.  

The results they obtained are shown in the following table: 

4.1 Name the path that is described in the passage. (2)  4.2 In relation to this path, what term is used to describe each of the following in terms of the role they  play? 

4.2.1 The muscles  (1)  4.2.2 Skin sensors  (1) 

4.3 Why should you advise the two learners to repeat the procedure more than three times for each  investigation? (2) 4.4 Identify the following in their investigation: 

4.4.1 The dependent variable  (1)  4.4.2 The independent variable   (1) 

4.6.1 The actual reaction time if the meter stick dropped 9 centimetres (2)  4.6.2 The distance the ruler will drop for a reaction time of 400 milliseconds  (2) 

QUESTION 5  The graph shows the speed of a nerve impulse along neurons with different diameters, measured in micrometres  (μm). 

5.1 Describe the relationship between the diameter of a neuron and the speed of an impulse travelling  along the neuron.  (2)  5.2 Use the graph to estimate how fast an impulse would travel along a neuron with a diameter of 5  μm. (2)  5.3 Name the functional gap found between two neurons across which impulses are transmitted.  (1)  5.4 Explain the significance of the myelin sheath that covers the neurons. (2)  5.5 Draw a diagram to illustrate the structure of a motor neuron. Indicate the direction of the impulse by  means of an arrow in the diagram.  (7) 

QUESTION 6  A person sitting in a darkened room covers one eye. A dim electric bulb, positioned at varying distances from the  person, is switched on at one-minute intervals for a period of 9 seconds. During this period the diameter of the pupil of  the eye is measured. The results obtained are shown in the table below. Study the table and answer the questions that  follow.

6.1 Name the structure in the eye that controls the size of the pupil.  (1) 6.2 Between which TWO time intervals did the following changes in the diameter of the pupil occur? 

6.2.1 Smallest increase   (2) 6.2.2 Biggest decrease   (2)

6.3 State why the size of the pupil changes from interval 8 to interval 9.  (2) 6.4 Describe how the size of the pupil changes from interval 8 to interval 9.  (4) 6.5 Why is the response in QUESTION 6.3 referred to as a ‘reflex’?  (1) 6.6 What is the significance of this reflex?  (1) 6.7 At which time interval was the bulb the furthest from the eye?   (1) 6.8 Explain your answer to QUESTION 6.7.   (2) 6.9 State TWO ways in which the investigator could ensure that the results of this investigation are  reliable.   (2) 6.10 State THREE things that must be kept constant in this investigation to ensure that it is valid.  (3)

[21] TOTAL SECTION B:  50 GRAND TOTAL: 100

6.4 Assignment 2 – Reproduction 

Instructions and information

NOTE: If it is not possible to schedule a single 90-minute session for this assignment, then SECTION A can be  done on one day in a 45-minute session and SECTION B the following day in another 45-minute session.  ________________________________________________________________________

SECTION A  QUESTION 1  Read the text below and then answer the questions that follow. 

1.1 State the type of fertilisation (external or internal) that occurs in bullfrogs and describe how it occurs.  State whether reproduction in bullfrogs is viviparous, oviparous or ovoviviparous.(3) 1.2 Explain your answer to QUESTION 1.2.  (1) 1.3 Describe TWO characteristics of a frog’s egg.   (2) 1.4 Give TWO reasons suggested in the article for bullfrog eggs to be laid in water.    (2) 1.5 Frog eggs are vulnerable to predators, since there is little or no parental protection.   (2) 1.6   Explain THREE strategies that ensure a good survival rate of tadpoles. 

QUESTION 2  The electron micrograph below is that of the human sperm. Study the micrograph and answer the questions that follow.  

2.1 Draw a labelled line diagram of the human sperm represented in the electron micrograph.   (6)  2.2  Use the scale line provided to calculate the width of the sperm at its widest point. (4)  2.3  Explain THREE ways in which the sperm is structurally suited for its role in fertilisation.   (6)    

QUESTION 3  Records of human fertility for the period 1941 to 1990 have shown changes in the sperm counts of normal men. The  table below summarises the changing percentages of men with high or low sperm counts over a period of 50 years. 

3.1  During which time period was there: 

3.1.1 The highest percentage of men with low sperm counts?  (1)  3.1.2 The lowest percentage of men with high sperm counts?   (1)  3.1.3 The greatest difference between men with high sperm counts and men with low sperm counts?  (1) 

3.2 Describe the trend for men with low sperm counts, and compare it with those with high sperm counts  over the period of 50 years.   (2)   3.3  Calculate the percentage increase in men with low sperm counts from 1971 to 1990. (2)  3.4  Suggest TWO reasons for the trend described in QUESTION 3.2.  (2) 

QUESTION 4  The table below shows the results of a survey on the use of contraceptives by a sample of women in a rural area. 

Draw a pie chart to show the results of the survey. Show all working. [9]

TOTAL SECTION A: 50

SECTION B  QUESTION 5  The diagram below shows the changes in the ovary, uterus and level of hormones during a 28-day menstrual cycle.  Study the diagram and answer the questions that follow. 

5.1 Which hormone is responsible for: 

5.1.1 Ovulation (1)  5.1.2 Primary (first) thickening of the endometrium (1) 

5.2 According to the graph, on which day(s) does each of the following occur: 

5.2.1 Menstruation  (1)  5.2.2 Ovulation (1) 

5.3 Two structures in the ovaries are responsible for the secretion of two female hormones.

5.3.1 Name the TWO structures and the hormones they secrete. (4)  5.3.2 Give evidence from the graph to support your answer to QUESTION 5.3.1. 4) 

5.4 Explain the interaction that occurs between the hormones FSH and progesterone and why it is  necessary. (3)  5.5 Is the female, whose cycle is represented in the diagram, pregnant?  (1)  5.6 Give TWO reasons from the graph for your answer to QUESTION 5.5.  (2) 

QUESTION 6  The table below shows the average human foetal length of males and females over a 40-week gestation period.  

6.1 Draw TWO sets of bar graphs on the same system of axes to compare male and female foetal  length over time.  (9)  6.2 State TWO conclusions that could be drawn from the results in the graph.  (4) 

[19]  TOTAL SECTION B: 50 

6.5 Test – Nucleic acids and meiosis 

• Draw diagrams and flow charts ONLY when requested to do so. 
• This test is to be done under controlled conditions and must be handed in at the end of the session. 

SECTION A  QUESTION 1  1.1 Various possible options are provided as answers to the following questions. Choose the answer  and write only the letter (A–D) next to the question number (1.1.1–1.1.5) in the ANSWER BOOK, for  example 1.1.6 D. 

1.1.1 All nucleic acids are made up of … 

• deoxyribose sugars, nitrogenous bases and phosphates.
• sugars, nitrogenous bases and phosphates.
• ribose sugars, nitrogenous bases and phosphates
• sugars, nitrogenous bases and sulphates. 

1.1.2 If a DNA molecule contains 20 000 base molecules, of which 20% are cytosine, how  many adenine molecules will be present? 

1.1.3 DNA replication ensures that all daughter cells formed as a result of … 

• mitosis, have identical genetic material.
• meiosis, have identical genetic material.
• mitosis, have half the number of chromosomes as the parent cell.
• meiosis, have half the number of chromosomes as the parent cell.

1.1.4 In individuals with normal haemoglobin, the mRNA for haemoglobin includes the codon  GAA. This sequence is changed in individuals with sickle cell anaemia so that their mRNA  has a codon GUA at the same location. This suggests that the DNA has undergone a  mutation involving a change of base sequence from ... 

Related Items

• PHYSICAL SCIENCES SCHOOL BASED ASSESSMENT EXEMPLARS - CAPS GRADE 12 LEARNER'S GUIDE
• PHYSICAL SCIENCES SCHOOL BASED ASSESSMENT EXEMPLARS - CAPS GRADE 12 TEACHER'S GUIDE
• ACCOUNTING SCHOOL BASED ASSESSMENT EXEMPLARS - CAPS GRADE 12 LEARNER'S GUIDE
• ACCOUNTING SCHOOL BASED ASSESSMENT EXEMPLARS - CAPS GRADE 12 TEACHER'S GUIDE
• ENGLISH FIRST ADDITIONAL LANGUAGE SCHOOL BASED ASSESSMENT EXEMPLARS - CAPS GRADE 12 TEACHER'S GUIDE
• ENGLISH FIRST ADDITIONAL LANGUAGE SCHOOL BASED ASSESSMENT EXEMPLARS - CAPS GRADE 12 LEARNER'S GUIDE
• GRADE 12 MATHEMATICS SCHOOL BASED ASSESSMENT EXEMPLARS - CAPS LEARNER'S GUIDE
• LIFE SCIENCES SCHOOL BASED ASSESSMENT EXEMPLARS - CAPS GRADE 12 TEACHER'S GUIDE
• LIFE SCIENCES SCHOOL BASED ASSESSMENT EXEMPLARS - CAPS GRADE 12 LEARNER'S GUIDE
• GEOGRAPHY SCHOOL BASED ASSESSMENT EXEMPLARS - CAPS GRADE 12 LEARNER'S GUIDE
• CAA to TAA.
• CTT to CAT.
• CUU to CAT.
• CTT to CTA. 
• Only suspect X was involved.
• Only suspect Y was involved.
• Suspects X and Y were both involved.
• Neither suspect X nor suspect Y was involved. (5 x 2) (10) 

1.2 Give the correct biological term for each of the following descriptions. Write only the term next to the  question number (1.2.1–1.2.4) in the ANSWER BOOK. 

1.2.1 Specific lengths of DNA which carry codes for specific characteristics of organisms 1.2.2 The part of protein synthesis taking place in the nucleus  1.2.3 The bonds between the two strands of a DNA molecule  1.2.4 The chromosome condition/ploidy of a somatic cell (4) 

1.3 Indicate whether each of the statements in COLUMN I applies to A only, B only, both A and B or  none of the items in COLUMN II. Write A only, B only, both A and B, or none next to the question  number (1.3.1–1.3.3) in the ANSWER BOOK.

(3 x 2) (6)  TOTAL SECTION A: 20

Identify the amino acids which will be brought to organelle G according to the code provided by the  mRNA found on G. (3)  2.6 Write down the triplet of DNA bases that correspond to each of the molecules B, F and H, respectively. (3) 

[15]  TOTAL SECTION B:  30  GRAND TOTAL:  50

7. Marking guidelines  7.1 Practical Task 1 – Surveying human characteristics 

• Seek permission✓ to conduct the investigation. 
• Decide how the learners are to be selected✓ for your sample. 
• Identify the 20 learners✓ who will form a part of the sample.
• Arrange a date✓/time/venue for surveying the different characteristics. 
•  Design a table✓ for recording information. 
• Study the different phenotypes for each characteristic✓ in order to correctly identify them.  (4) (any 4) 
•             2.1 Number of learners ✓ that have free or attached ear lobes   (1) 2.2 Characteristic✓/type of ear lobe/attached or unattached earlobes   (1)
• There are more✓ learners✓ in the school that are tongue rollers than non-rollers✓
• There are more✓ learners✓ in the school that are non-rollers than tongue rollers✓ 
• The number of learners✓ in the school that are tongue rollers is equal✓ to the number of  non-rollers✓ (any 1 x 3) (3)
• Support✓(if the results obtained are in line with the hypothesis stated by the learner in Question 3) OR Reject✓ (if the results obtained contradict the hypothesis stated by the learner in (Question 3) (1)
• Increase the sample size✓ 
• Repeat the investigation✓   (2)

7.2 Practical Task 2 – Simulating natural selection 

• More✔ white circles✔ than newspaper circles✔ will be picked up from the white sheet OR More✔ newspaper circles✔ than white circles✔ will be picked up from the white sheet OR An equal number✔ of newspaper circles✔ and white circles✔ will be picked up from the white sheet 2.  (3) 
• Same size of newspaper and white paper used as a background✔
• Same size of white and newspaper circles✔
• Same number of white and newspaper circles at the start✔
• Same amount of time allowed for picking up the circles✔
• Same forceps/tweezers used throughout the investigation✔
• Same person used to pick up circles throughout the investigation✔ 
• Same hand used to pick up circles throughout the investigation✔ (any 2)   (2)
• Fewer✔ white circles✔ were picked up from the white paper, because white circles are not easily  seen against the white paper✔  OR More✔ newspaper circles✔ were picked up from the white paper, because newspaper circles are easily seen against the white paper✔    (3) 
• Increase number of attempts✔ and work out the average number picked  
• Repeat the investigation ✔ (any 1)    (1)
• More✔ white circles✔ than newspaper circles✔ were picked up from the newspaper background (3) 
• Support✓ (if the results obtained are in line with the hypothesis stated by the learner in Question 1) OR  Reject✓ (if the results obtained contradict the hypothesis stated by the learner in Question 1)   (1) 
• The white sheet represents the light tree✓
• and the newspaper sheet represents the dark tree✓. 
•  The circles represent the moths.✓
• Picking up the circles represents birds feeding on the moths✓.
• More circles of one type rather than the other type being picked up✓ represents natural selection✓ (any 5) (5) 

7.3 Assignment 1 – Response to the environment QUESTION 1  1.1 

1.1.1 Presence/absence of auxins✔  (1)  1.1.2 Growth of lateral buds✔  (1)  1.1.3

• Use bean plants of the same species✔ 
• Conduct investigation under same environmental conditions✔ 
• Use bean plants of the same height/age✔ (any 2)   (2)

1.2 Auxins✔ at the growing tip of the stem stimulate✔ the growth of lateral buds✔  OR  Auxins✔ at the growing tip of the stem inhibit✔ the growth of lateral buds✔  OR  Auxins✔ at the growing tip of the stem have no effect✔ on the growth of lateral buds✔  (3)  

• Auxin present✔ in Group 3 as it was applied to the tip and therefore it inhibited✔ the growth  of the lateral buds 
• Auxins not present✔ in rest of stem in Group 4 due to the barrier so lateral buds grew✔/  growth of lateral buds was not inhibited  (4)  

1.4 Support✓ (if the results obtained are in line with the hypothesis stated by the learner in   Question 1.2)  OR  Reject✓ (if the results obtained contradict the hypothesis stated by the learner in  Question 1.2)   (1) 

QUESTION 2  2.1  Gravity✔   (1)  2.2   

• Due to gravity, auxins accumulate✔ 
• on the lower side of the root✔. 
• A high concentration of auxins in the lower part of the root inhibits✔ growth.
• Cells on the upper part of the root grow faster✔ 
• where the auxin concentration is lower✔. 
• The root curves downwards✔.
• It is said to be positively geotropic✔. (any 6)    (6) 

2.3 Cell division ✔; cell elongation✔; the development of fruit✔; the abscission of leaves and fruit✔; the development of adventitious roots in stem cuttings ✔ (any 2)  (2)   2.4  Yes ✔ (1)   2.5  The growth is in response to gravity✔ and not light✔  (2)  2.6  Moisture is essential✔ for germination✔.  (2) 

QUESTION 3  3.1 Patient is diabetic if blood glucose level is above 200 mg/100 ml✔ for up to two hours after the  glucose test drink✔.   (2)  3.2 

3.2.1 Insulin level will increase between 30 and 60 minutes✔ and then  decrease✔. (2)   3.2.2 The level would initially increase when glucose level is higher than  normal✔then decrease when the level of glucose decreases✔.  (2) 

(260 mg/100 ml – 130 mg/100 ml) = 130 ✔   130/130 X 100✔  = 100%✔     (3) 

3.5   Adult 1: Adult 2: Adult 3 = 80 :240 :160✔ = 1 :3 :2✔   

3.6.1 IDDM - no insulin is produced✔  because the pancreatic cells responsible for insulin secretion are not functioning✔/do not produce insulin. (2)  3.6.2 NIDDM – insulin secretion will increase✔  since the pancreas is not affected✔/cells that normally respond become less sensitive to insulin (2) 

SECTION B QUESTION 4  4.1 Reflex arc ✓ ✓   (2) 4.2   

4.2.1 Effectors✓  (1) 4.2.2 Receptors✓   (1)

4.3 To improve ✓the reliability✓ of the investigation  (2) 4.1

4.4.1 Distance on meter stick/reaction time ✓ (1) 4.4.2 Different senses (sight/hearing/touch) ✓ (1)

5 cm + 6 cm + 6 cm = 17 cm ✓  17 cm = 5,7 cm ✓    3 ✓                                                     (3)

4.6.1 475 ✓ milliseconds ✓  (2)  4.6.2 3 ✓ cm✓  

QUESTION 6  6.1  Iris✔  (1)  6.2 

6.2.1 2✔to 3✔  (2)  6.2.2 6✔ to 7✔   (2) 

6.3 Dim light conditions✔ causes pupil to adjust  so that more light can enter✔ the eye (2)  6.4     

• Radial muscles✔ of iris contract✔
• Circular muscles✔of iris relax✔ 
• Pupil dilates✔ (any 4)  (4) 

6.5  It occurs automatically✔/involuntarily/without the control of the will (1)  6.6  It protects✔ the eye from damage in bright conditions  (1)  6.7  Interval 5✔ (1)  6.8  Diameter of the pupil✔ was at its widest✔  (2)  6.9 

• Repeat the investigation✔
• Take more than one reading at each time interval✔  
• Increase the time of exposure to light at each time interval✔ (any 2)  (2) 
• Use the same light bulb✔
• Same eye must be covered✔ throughout the entire investigation  
• Same person must be used✔ for the entire investigation  (3) 

[21]  TOTAL SECTION B:  50  GRAND TOTAL:   100

7.4 Assignment 2 – Reproduction SECTION A  QUESTION 1  1.1 Fertilisation occurs externally ✔ (1)        Eggs are released into the water and then male releases sperms✔ which fertilise eggs in the water✔ (2)  (3)  1.2  Oviparous✔ (1)  1.3 

• Eggs are laid✔
• and the embryos develop outside the mother’s body within the eggs✔ (2) 
• Eggs are small ✔
• Eggs are protected by a gelatinous mass and membranes✔ (2) 
• Prevents drying out✔ 
• Easier for frog sperm to reach the eggs✔  (2) 
• Large numbers of eggs are produced✔  because many are eaten✔
• Eggs hatch into tadpoles within 3-5 days✔  which ensures that they can swim away from predators✔
• Nearby plant matter shelters hatching tadpoles✔  preventing them from being eaten✔  (6) 

1 µm = 4 mm✔  Width of sperm = 12 mm✔ = X µm   1 µm = 4 mm  X µm = 12 mm ✔  X = 3 µm ✔                            (4)  

• The acrosome produces enzymes ✔  which help the sperm to penetrate the ovum ✔
• The middle piece of the sperm contains mitochondria ✔  that supply the energy for the sperm’s activity✔
• A tail is present✔  to move the sperm through the seminal fluid✔    (6)  

QUESTION 3  3.1 

3.1.1 1981–1990 ✔   (1)  3.1.2 1981–1990 ✔   (1)  3.1.3 1941–1950 ✔   (1) 

3.2 Men with low sperm counts have increased ✔ while  men with high sperm counts have decreased ✔  (2)   3.3  

% increase = 18- 14 ✔   = 4 ✔ %                             (2)  

• Changed diets✔/eating more processed foods by men have caused the change
• Increased stress✔/changed lifestyle has caused the change  (2) 

QUESTION 4  CALCULATIONS: 

[9]  TOTAL SECTION A: 50

SECTION B QUESTION 5  5.1 

5.1.1 LH ✔  (1)  5.1.2 Oestrogen ✔   (1) 

5.2.1 0–7 days ✔ (1)  5.2.2 Day 14 ✔      (1) 

• Graafian follicle ✔ - oestrogen ✔ 
• Corpus luteum ✔ - progesterone ✔   (4) 
• When Graafian follicle is formed ✔ 
• there is an increase in oestrogen ✔ 
• When corpus luteum is formed ✔
• there is an increase in progesterone✔  (4) 
• An increase in progesterone level ✔ 
• inhibits the release of FSH✔ 
• to prevent FSH from stimulating the development of an ovum✔ 
• since no further ova are required if pregnancy results✔ (any 3)  (3) 

5.5  No ✔ (1)  5.6 

Corpus luteum has degenerated ✔ Progesterone has decreased✔  FSH started to increase at the end of the cycle✔ (any 2)      (2) 

• Average foetal length of both males and females✓ are the same from 8 to 13 weeks✓ (9)
• Average foetal length of males is greater✓ than the average foetal length of females from 16  to 40 weeks✓ 
• Average foetal length increases for males and females✓ over the 40-week period ✓  (any 2 x 2)    (4) 

QUESTION 7  7.1 

Allocate marks for the following labels:   P1/parents and F1/offspring✓  Meiosis and fertilisation✓ (1 compulsory* + 6 others)   (7)  7.2 

(1 compulsory* + 6 others) 

(5)  [19]  TOTAL SECTION B: 50  GRAND TOTAL:  100

7.5 Test – Nucleic acids and meiosis SECTION A  QUESTION 1  1.1

1.1.1 B✓✓  1.1.2 C✓✓  1.1.3 A✓✓  1.1.4 B✓✓  1.1.5 D✓✓ (5 x 2) (10) 

1.2.1 Genes✓  1.2.2 Transcription✓  1.2.3 Weak hydrogen bonds✓ 1.2.4 Diploid✓ (4) 

1.3.1 B only✓✓  1.3.2 A only✓✓  1.3.3 A only✓✓  (3 x 2) (6)

TOTAL SECTION A: 20

SECTION B QUESTION 2  2.1 Protein synthesis✔ (1)  2.2  Translation✔ (1)  2.3 

• According to the mRNA codons✓
• tRNA with matching anticodons✓ 
• bring the required amino acids✓ to the ribosome 
• The amino acids become attached by peptide bonds✓ 
• to form the required protein✓ (any 5) (5) 
• Both are single-stranded 
•  Both are made up of ribose sugar 
• Presence of cytosine, guanine, adenine and uracil (any 2) (2) 

2.5 Histidine ✔ cysteine ✔ serine ✔ (3)  2.6 GTT ✔ GGT ✔ AGC ✔ (3) 

B – centromere✔ (2)  E – homologous chromosomes✔/bivalent 

• They allow for attachment of chromosomes✔ (2)
• They contract to pull the chromosomes/chromatids to the poles✔ 

3.3 Crossing over✔ takes place Chromatids overlap✔  Segments of chromatids are exchanged✔ (any 2)  (2) 

 Table ✔  (5)  3.5  Two✔  (1)  3.6 

• Chromosome number 21 fails to separate✔ 
• during anaphase 1✔
• Gametes will be formed with 24 chromosomes/one extra copy of chromosome number  21✔ 
• If such a gamete fuses with a normal gamete with 23 chromosomes✔
• The resulting zygote will have 47 chromosomes✔ (any 3)   (3) 

 [15]  TOTAL SECTION B:   30 GRAND TOTAL:   50

Related items

• Mathematics Grade 12 Investigation 2023 Term 1
• TECHNICAL SCIENCES PAPER 2 GRADE 12 QUESTIONS - NSC PAST PAPERS AND MEMOS JUNE 2022
• TECHNICAL SCIENCES PAPER 1 GRADE 12 QUESTIONS - NSC PAST PAPERS AND MEMOS JUNE 2022
• MATHEMATICS LITERACY PAPER 2 GRADE 12 MEMORANDUM - NSC PAST PAPERS AND MEMOS JUNE 2022
• MATHEMATICS LITERACY PAPER 2 GRADE 12 QUESTIONS - NSC PAST PAPERS AND MEMOS JUNE 2022

Ask Another Question

Follow class ace :.

Snapsolve any problem by taking a picture. Try it in the Numerade app?

Tongue-rolling phenotypes and geographical variation in the United Kingdom

Affiliation.

• 1 Department of Medical Biochemistry and Genetics, Tehran University of Medical Sciences, Iran.
• PMID: 2629620

The distribution of tongue-rolling phenotypes in a sample (n = 477) of undergraduate students of the University College of Swansea (U.K.) was studied. The birthplaces of these students were also recorded. England was divided into six areas, and Wales was left as an area on its own. The data suggest that those students who come from north-east are more non-rollers, which may be due to mixture with Scandinavians.

• Gene Frequency
• Genetics, Population*
• Tongue / anatomy & histology*
• Tongue Habits*