write a short note of photosynthesis

ENCYCLOPEDIC ENTRY

Photosynthesis.

Photosynthesis is the process by which plants use sunlight, water, and carbon dioxide to create oxygen and energy in the form of sugar.

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Learning materials, instructional links.

• Photosynthesis (Google doc)

Most life on Earth depends on photosynthesis .The process is carried out by plants, algae, and some types of bacteria, which capture energy from sunlight to produce oxygen (O 2 ) and chemical energy stored in glucose (a sugar). Herbivores then obtain this energy by eating plants, and carnivores obtain it by eating herbivores.

The process

During photosynthesis, plants take in carbon dioxide (CO 2 ) and water (H 2 O) from the air and soil. Within the plant cell, the water is oxidized, meaning it loses electrons, while the carbon dioxide is reduced, meaning it gains electrons. This transforms the water into oxygen and the carbon dioxide into glucose. The plant then releases the oxygen back into the air, and stores energy within the glucose molecules.

Chlorophyll

Inside the plant cell are small organelles called chloroplasts , which store the energy of sunlight. Within the thylakoid membranes of the chloroplast is a light-absorbing pigment called chlorophyll , which is responsible for giving the plant its green color. During photosynthesis , chlorophyll absorbs energy from blue- and red-light waves, and reflects green-light waves, making the plant appear green.

Light-dependent Reactions vs. Light-independent Reactions

While there are many steps behind the process of photosynthesis, it can be broken down into two major stages: light-dependent reactions and light-independent reactions. The light-dependent reaction takes place within the thylakoid membrane and requires a steady stream of sunlight, hence the name light- dependent reaction. The chlorophyll absorbs energy from the light waves, which is converted into chemical energy in the form of the molecules ATP and NADPH . The light-independent stage, also known as the Calvin cycle , takes place in the stroma , the space between the thylakoid membranes and the chloroplast membranes, and does not require light, hence the name light- independent reaction. During this stage, energy from the ATP and NADPH molecules is used to assemble carbohydrate molecules, like glucose, from carbon dioxide.

C3 and C4 Photosynthesis

Not all forms of photosynthesis are created equal, however. There are different types of photosynthesis, including C3 photosynthesis and C4 photosynthesis. C3 photosynthesis is used by the majority of plants. It involves producing a three-carbon compound called 3-phosphoglyceric acid during the Calvin Cycle, which goes on to become glucose. C4 photosynthesis, on the other hand, produces a four-carbon intermediate compound, which splits into carbon dioxide and a three-carbon compound during the Calvin Cycle. A benefit of C4 photosynthesis is that by producing higher levels of carbon, it allows plants to thrive in environments without much light or water. The National Geographic Society is making this content available under a Creative Commons CC-BY-NC-SA license . The License excludes the National Geographic Logo (meaning the words National Geographic + the Yellow Border Logo) and any images that are included as part of each content piece. For clarity the Logo and images may not be removed, altered, or changed in any way.

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Photosynthesis

All you need to know about photosynthesis.

Photosynthesis is the process by which a plant produces its food by converting light energy into chemical energy. Plants use water, carbon dioxide and sunlight in the presence of chlorophyll to produce their food or energy in the form of sugar and release oxygen as the byproduct. Understanding the process of photosynthesis means a clear concept about the different cellular and chemical activities going on in the plant body. The word photosynthesis is coined from the Greek word for meaning light along with synthesis. This implies a synthesis i.e a chemical reaction using light energy. This is not always for green plants only but certain bacteria and prokaryotes also use this process to prepare their food. In green plants or algae, the synthesis takes place within an important organelle called chloroplast where the pigment chlorophyll is present. Chlorophyll occurs in their leaves, stems, flowers, sepals and even in plastids.

Factors Affecting Photosynthesis

Various factors influence/affect the photosynthesis process. These are:

Light Intensity: More the light, the more will be the rate of photosynthesis. Similarly, low light will lead to a low rate of photosynthesis.

The Concentration of CO 2 : A higher CO 2 concentration rate in a plant also accelerates the photosynthesis process. The required amount of CO 2 is 300-400 PPM.

Temperature: If the temperature is between the range of 25 to 35 degrees Celsius, photosynthesis takes place effectively.

Water: An essential amount of water is required for stomatal opening, and it’s a key factor in the process of photosynthesis.

Pollution: The increasing rate of polluting particles in the atmosphere block the pores of somatic cells, and the intake of carbon dioxide becomes difficult.

Photosynthesis Equation

Carbon dioxide and water are the two major factors involved in the photosynthesis reaction. It’s an endothermic reaction, and the products resulting from it are oxygen and glucose. The formula is:

\[6CO_{2} + 6H_{2}O = C_{6}H_{1}2O_{6} + 6O_{2}\]

However, some bacteria don’t produce oxygen as a by-product of photosynthesis. They are called anoxygenic photosynthetic bacteria, and those who do it are called oxygenic photosynthetic bacteria.

Photosynthetic Pigments

Four types of photosynthetic pigments are present in the leaves of the plants. They are:

Chlorophyll a

Chlorophyll b

Xanthophylls

Carotenoids

Structure of Chlorophyll

Chlorophyll is a green colour pigment found in plants that play a vital role in photosynthesis. It allows the plants to absorb the energy coming from the sunlight, which is essential for photosynthesis.

Process of Photosynthesis

The photosynthesis process occurs in plants. It takes place in chloroplasts at the cellular level that contains chlorophyll. Leaves have parts called the petiole, epidermis, and lamina that absorb sunlight.

Photosynthesis Steps:

The photosynthesis process takes place at two levels or steps. These are:

Light Reaction of Photosynthesis (or) Light-dependent Reaction

The process begins in the daylight, by gathering the light. The two types of photosystems convert light energy into ATP and NADPH. During their conversion, oxygen is produced, and water is used. The equation of this step is:

\[2H_{2}O + 2NADP + 3ADP + 3P_{i} = O_{2} + 2 NADPH + 3ATP\]

The Dark Reaction of Photosynthesis (or) Light-independent Reaction

This is also called carbon-fixing. It is not dependent on light and takes place in chloroplast where the products from the earlier step are used. Plants intake CO 2 and the Calvin Photosynthesis Cycle begins, where the six molecules of CO 2 are converted into sugar or glucose.

\[3CO_{2} + 6NADPH + 5H_{2}O + 9ATP = G3P + 2H + 6NADP + 9ADP + 8P_{i}\]

Importance of Photosynthesis

The photosynthesis process is very important for the survival of living beings, and to continue the food chain. It also produces oxygen, which is required for breathing.

FAQs on Photosynthesis

1. What is photosynthesis?

The process by plants, of producing nutrients essential for survival.

2. What happens in a photosynthesis process?

The nutrients and glucose required for plants, and oxygen required for the animals, is created during the process.

3. What is the photosynthesis reaction?

A reaction taking place in plants that results in the production of glucose and oxygen.

4. What is shown in a photosynthesis diagram?

The photosynthesis diagram shows how the plants take sunlight and use it to produce essential nutrients and oxygen.

5. Why is photosynthesis in plants important?

It helps in the survival of the plants, the creation of products essential for the survival of living beings, and also to maintain the environmental balance.

6. How long is the photosynthesis cycle?

The whole process of photosynthesis, right from absorbing the light up to the final stage, takes place in just 30 seconds!

7. What is included in the mechanism of photosynthesis?

The mechanism of photosynthesis is an oxidation (oxygen releasing) and reduction reaction. It produces glucose along with oxygen.

8. What are the two phases of photosynthesis?

Photosynthesis is a synthesis reaction in which solar energy gets converted to chemical energy. However, the few steps involved in the synthesis also occur without light and based on that there are two phases of photosynthesis. The light-dependent reactions and the light-independent phase. In the light-dependent phase which is the starting phase the molecule of chlorophyll pigment absorbs one photon from the sun rays and loses electrons and ultimately after several steps generate NADPH and ATP which are used in the second phase or the light-independent phase of the reaction. In the dark phase, the atmospheric carbon dioxide is captured by a photosynthetic enzyme that uses the NADPH formed in the first phase to produce 3 carbon sugars which ultimately gets converted to starch and sucrose. Thus the two phases occur subsequently to form the end products which are the food of the plant.

9. What is the efficiency of the photosynthetic reaction?

Photosynthesis is the most important reaction or synthesis for which lives and the planet can run. It converts light to chemical energy. The efficiency of the reaction is however only 3-6% and the absorbed light cannot be used. The unused light gets dissipated to the atmosphere as heat. The efficiency of the synthesis varies with temperature, light intensity and proportion of carbon dioxide in nature which can vary the efficiency to a maximum of 8% even. The efficiency of the two phases can be separately taken into count and they both separately contribute to the total efficiency of the process.

10. Which factors can affect the process of photosynthesis?

Photosynthesis is affected by many factors including the corollary ones. The main factors that affect the process are as follows:

Light: Its intensity and wavelength

Carbon dioxide: Its concentration in the atmosphere

Temperature: Favorable temperature is needed

Water: Suitable quantity of water is needed

Apart from these factors photosynthesis also depends upon the factor referred to as the corollary factor which is the surface area of the leaf available to absorb the sunlight. This is why if a plant is overshadowed by other big trees it cannot efficiently photosynthesize.

11. What are the actual stages of the process of photosynthesis?

The process of photosynthesis can be divided into four essential steps. They are as follows:

Transfer of solar energy in thylakoid membranes of chlorophyll.

Transfer of the electrons in the light reaction

The synthesis of electron transport chain and ATP in the thylakoid membrane.

Absorption and fixation of carbon dioxide from the atmosphere with the formation of resulting stable plant food.

Each of these steps takes a specific time to happen with the maximum time of one second taken by the last step.

12. How is photosynthesis essential for the ecosystem?

Photosynthesis is the procedure by which plants convert solar energy into chemical energy in the form of their food. Photosynthesis is an ideal process for a living organism that has not evolved the capacity to actively move around in order to obtain food. Photosynthesis is also important for the consumers of the food web and thus is the starting point of all food chains of the ecosystem. Photosynthesis is thus an essential living process for plants and the ecosystem.  All life on the earth depends upon photosynthesis, not only for the food but also for the oxygen in the atmosphere which is essential for them to respire. It is the process of photosynthesis that purifies the atmosphere by removing carbon dioxide from the environment and converting it to oxygen.

Biology • Class 11

Photosynthesis

Class 7 - living science biology ratna sagar, check your progress.

Green plants make their own food by the process of respiration.

Corrected statement — Green plants make their own food by the process of photosynthesis.

The glucose produced during photosynthesis is transported from the leaves to other parts of the plant.

Carbon dioxide is released as an end product during photosynthesis.

Corrected statement — Oxygen is released as an end product during photosynthesis.

Stomata are present mostly on the upper surface of leaves and on green stems.

The rate of photosynthesis increases with an increase in the concentration of carbon dioxide.

Tick the most appropriate answer

Plants make their own food by a process called

• respiration

photosynthesis

Reason — The process by which plants make their own food is called photosynthesis

During the process of photosynthesis, plants use energy from the

Reason — Plants convert the energy of sun into chemical energy of food (glucose)

The green pigment present in leaves is called

• chlorophyll
• chloroplast
• chromoplast
• anthocyanin

Reason — The green pigment present in leaves is called chlorophyll which is present in chloroplasts

Small pores on the lower surface of leaves are called

Reason — Stomata are small openings on the leaves present mostly on the lower surface of leaves and on green stems.

Each stoma has two bean-shaped cells called

guard cells

Reason — Each stomata has two bean-shaped cells called guard cells. They regulate the opening and closing of stomata.

When the guard cells lose water, they lose their turgidity and the stomata

• remains same

Reason — When the guard cells lose their turgidity, their inner walls come closer and the stomata closes.

If the colour of a leaf changes to blue-black when a few drops of iodine are added to it, then it shows the presence of

Reason — Iodine changes the colour of leaf to blue-black showing the presence of starch and thus shows the photosynthesis in that leaf.

The optimum temperature at which the photosynthesis occurs best is around

Reason — The optimum temperature range for photosynthesis is 20°C to 40°C.

Fill in the blanks

All organisms need ............... to live and grow.

All organisms need energy to live and grow.

Animals get their food from ............... and other animals.

Animals get their food from plants and other animals.

The ............... produced during photosynthesis is transported from the leaves to the other parts of the plant.

The glucose produced during photosynthesis is transported from the leaves to the other parts of the plant.

The inner walls of the guard cells are ............... than the outer walls.

The inner walls of the guard cells are thicker than the outer walls.

............... absorbs light.

Chlorophyll absorbs light.

The rate of photosynthesis ............... with an increase in the concentration of carbon dioxide.

Answer these questions in short

Where do living organisms obtain energy from?

The living organism obtain energy from the food they eat. Animals get their food from plants and other animals. Plants on the other hand, make their own food by the process of photosynthesis.

How do green plants make their own food?

Green plants make their own food by the process of photosynthesis. Plants convert carbon dioxide and water into glucose in presence of light and chlorophyll.

How is glucose stored in plants?

The glucose is converted into starch and stored in various storage organs within the plant.

What happens when the guard cells are full of water?

When the guard cells are full of water, they swell and bulge outwards and the stomata opens.

Can plants make food in the absence of light? Why?

Light is very important for photosynthesis. In the absence of light, plants cannot make their food. Light energy is required to convert raw materials of photosynthesis into glucose.

Answer these questions in detail

Explain photosynthesis. Represent photosynthesis using a word equation.

The process by which green plants use energy from the sun to convert carbon dioxide and water into glucose in the presence of green-coloured pigment (chlorophyll) is called photosynthesis. Plants obtain carbon dioxide from the atmosphere through stomata and water is absorbed by the roots from the soil. The process of photosynthesis involves following steps:

• Water taken up by the root system and carbon dioxide from the atmosphere reaches the leaves.
• Light is absorbed by chlorophyll, which splits water (called photolysis) and oxygen is released. This reaction depends on sunlight for activation energy. It takes place in the thylakoids of the chloroplasts.
• Carbon dioxide splits and this carbon is used to make sugars. This reaction does not require light energy. It occurs in stroma.
• Sugars are formed and they combine to form complex sugars. Glucose and fructose are formed as a result of photosynthesis.

Photosynthesis can be represented by the following word equation:

Carbon dioxide + water → chlorophyll sunlight \xrightarrow[\text{chlorophyll}]{\text{sunlight}} sunlight chlorophyll ​ Glucose + Oxygen

Write a short note on stomata.

Small openings on the leaves present mostly on the lower surface of leaves and on green stems are called stomata. Each stoma has two bean-shaped cells called guard cells. The inner walls of the guard cells are thicker than the outer walls. When the guard cells are full of water, they swell and bulge outwards and the stomata opens. When the guard cells lose water, they lose their turgidity and the stomata closes. Normally stomata remains open during the day and closes at night. Stomata have following functions:

• Exchange of gases (carbon dioxide and Oxygen)
• Transpiration (loss of water from the plant surface)

Explain any three factors that affect photosynthesis.

Following are the three factors that affect photosynthesis:

• Light — Light energy trapped by the chlorophyll is used to convert raw materials into sugar. The rate of photosynthesis also depends on the intensity of the light, higher the intensity of light higher is the rate of photosynthesis.
• Chlorophyll — It is found in structures called chloroplasts. It enables the plant to trap light energy.
• Temperature — The series of chemical reactions occurring during photosynthesis can take place only at a suitable temperature, the optimum being between 20°C to 40°C.

How will you test the presence of starch in green leaves?

To test the presence of starch in green leaves, following steps are followed:

• Pluck a leaf from a plant which has been exposed to sunlight for a few hours.
• Put it in a test tube containing alcohol. Place the test tube in a beaker containing water and heat the water. As the alcohol begins to boil, the chlorophyll dissolves in it and the leaf becomes pale.
• Remove the leaf from alcohol and wash it in warm water.
• Lay the leaf in a dish and put a few drops of iodine on it.

We will observe that the colour of the leaf changes to blue-black. This shows that starch is present in the leaf.

How will you show that chlorophyll is necessary for photosynthesis?

To show that chlorophyll is necessary for photosynthesis, we will conduct following experiment:

• Select a plant with variegated leaves. Chlorophyll is present in the green portion.
• Put the plant in sunlight for a few hours.
• Pluck any leaf and draw its rough outline indicating the green and non-green portions.
• put the leaf in dilute iodine solution.

We observe that the portion of leaf with chlorophyll turns blue-black showing the presence starch. This shows that photosynthesis took places only in the green part of leaf. Thus, chlorophyll is necessary for photosynthesis.

Write a short note on the significance of photosynthesis.

The process of photosynthesis is of extreme importance as it is the source of food as well as oxygen for all animals directly or indirectly. Food is produced by the process of photosynthesis. Leaves capture light energy from the sun and use it to make food. Animals that feed on the plants get this energy. They pass it on further when they are eaten by other animals. The energy obtained from food is used by all organisms for various metabolic activities. All living organisms require oxygen. This oxygen is released by the plants during photosynthesis. In the absence of photosynthesis, the oxygen level in the atmosphere would decrease and life on earth would become impossible.

Look at the picture and answer the questions that follow

• What does this picture show?
• Where are these structures found in a plant?
• What are their functions?
• The given picture shows Stomata.
• They are found on the lower surface of leaves and on green stems.
• Their functions are exchange of gases (carbon dioxide and oxygen) and transpiration.
• Identify the activity for which this set is required.
• Which liquid is being added to the leaf?
• What happens to the part of leaf covered with black paper? What does this indicate?
• It is used to show that light is necessary for photosynthesis.
• Iodine solution is added to the leaf.
• The part of the leaf covered with the black paper does not turn blue-black after adding iodine solution. This indicate that there is no starch formed in that area since no photosynthesis took place because that area of leaf was kept devoid of light. Hence, this activity proves that light is essential for photosynthesis.

Think and answer

We make our own food in the kitchen. This means that humans are also autotrophs. Do you agree?

No, we are not autotrophs. Autotrophs are the organisms that are capable to convert solar energy into food. We can cook food produced by plants but cannot produce it like autotrophs.

Can animals make food from carbon dioxide, water and sunlight like plants do? Why?

No, animals cannot make food from carbon dioxide, water and sunlight like plants do because they do not have chlorophyll and the mechanism to trap light energy and convert it into food. Hence, animals are not capable of performing photosynthesis to make their own food.

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Write a short note on photosynthesis.

Answers (1).

• Photosynthesis is an important process by which food is formed.
• The plants make food using sunlight and water, which provides nourishment to other organisms and themselves.
• Photosynthesis reaction is as follows :

                              6CO2 + 12H2O -------->  C6H12O6  + 6O2 + 6H2O                      (Carbon dioxide)  + (Water) ---> (Glucose) + (Oxygen) + (Water) The following events occur during this process of photosynthesis :

• Absorption of light energy by chlorophyll.
• Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen
• Reduction of carbon dioxide to carbohydrates.

Ritika Jonwal

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2.23: Photosynthesis Summary

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As a result, the guard also helps in reducing the water loss through transpiration by regulating the opening. Likewise, guard cells, subsidiary cells are also present in support. The subsidiary cells protect the epidermal cells against guard cell expansion.

Moreover, it plays a major role in photosynthesis. Photosynthesis is the process by which various plants make their food. They take in light energy and convert it into chemical energy. Furthermore, light energy converts carbon dioxide, water, and minerals into oxygen.

Thousands of stomata are present on the lower part of the leaf i.e. the underlying part. As a result heat exposure and loss of water due to transpiration get reduced. However, in aquatic plants, it lies on the upper surface. For instance, there are various types.

Various Types of Stomata

• Anomocytic Stomata
• Anisocytic Stomata
• Diacytic Stomata
• Paracytic Stomata
• Gramineous Stomata

Anomocytic Stomata – These are irregularly shaped and they look similar to epidermal cells.

Anisocytic Stomata – They have three subsidiary cells surrounding each stoma. However, they are not of the same size. The third is smaller than the other two cells.

Diacytic Stomata – Each stoma is perpendicular to the subsidiary cells.

Paracytic Stomata – Two subsidiary are parallel to the stomatal pore and the guard cells.

Gramineous Stomata – In this the guard cells are wider at the end and narrow in the middle. Further, the guard cells are parallel to the subsidiary cells.

How Does it Work in Photosynthesis?

Stomata help in the gas exchange because of which the photosynthesis in plants takes place. Photosynthesis is the process in which the plants take in carbon dioxide and breathe out oxygen as a waste product. The carbon dioxide intake combines with water in the presence of sunlight to make glucose and energy-rich compounds.

Furthermore, all these reactions take place in the chloroplasts present in the guard cells. Chloroplasts are organelles that produce food, they are similar to mitochondria in an animal cell.

When the air temperature rises the stomata opens the pores to let carbon dioxide in. After entering through the pores the plant starts preparing food through photosynthesis. This process produces oxygen as a by-product which is poisonous to the plant.

Therefore the plants release it out through the stoma. However, at night the vice versa happens. The glucose recombines with oxygen to again produce water and carbon dioxide. In this reaction, the excess water gets released through the stomata again. The water gets evaporated into the atmosphere with the help of a process called transpiration.

In conclusion, it does not play a direct role in photosynthesis but is an important organelle . Furthermore, stomata in plants play an active role in conserving the water. As a result, it maintains the hydration of the plant that is a necessary function.

Solved Question on Stomata

Question . Where are stomata present in a non-aquatic plant?

A . On the upper part of the leaf B . On the lower part of the leaf C . On the roots D . On the tip of the leaf

Answer . Option B is correct. Stomata are present in the lower part of the leaf. To prevent the loss of water through transpiration.

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Write a note on Photosynthesis.

Carbon Dioxide + Water + Sunlight → Glucose + Oxygen

1) Plants take up carbon-dioxide from the atmosphere through the tiny pores known as stomata present on the surface of the leaves.

2) Plants absorb the water and minerals from the soil with the help of roots and transport them to the leaves of the plant where synthesis of food takes place.

3) The green pigment, chlorophyll present in plant leaves, helps the leaves to capture sunlight. Sunlight is the source of energy to carry out photosynthesis.

4) In the presence of sunlight, chlorophyll acts on carbon dioxide, minerals, and water to produce carbohydrates. These carbohydrates are stored in the plant leaves in the form of energy.

5) The process of photosynthesis also releases oxygen into the atmosphere.

The reaction of photosynthesis process is commonly written as:      

           6CO 2     +      6H 2 O            Sun-light ------->       C 6 H 12 O 6          +    6O 2

Carbon dioxide         Water          Chlorophyll                Carbohydrates      Oxygen

During the process of photosynthesis, six carbon dioxide molecules (reactant) and six water molecules (reactant), are converted into one sugar molecule (carbohydrate) (product) and six oxygen molecules (byproduct) in the presence of light energy (sunlight) captured by chlorophyll.

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• Biology Article
• Photorespiration

Table of Contents

• Photosynthesis
• Important Questions

When the carbon dioxide concentration inside a leaf drops, photorespiration takes place. This takes place mostly on warm arid days when plants are compelled to shut their stomata to avert surplus water loss. The oxygen proportions of the leaf will automatically surge if the plants keep trying to fix carbon dioxide when their stomata are shut, all the carbon dioxide stored will be consumed and the oxygen proportions will surge when compared to carbon dioxide levels.

What is Photorespiration

Photorespiration is a process that occurs in Calvin Cycle during plant metabolism. In this process, the key enzyme RuBisCO that is responsible for The fixing of carbon dioxide reacts with oxygen rather than carbon dioxide. It occurs because of the conditions in which carbon dioxide concentration falls down and rubisco does not have enough carbon dioxide to fix and it starts fixing oxygen. Under suitable conditions, C3 plants have sufficient water, the supply of carbon dioxide is abundant and in such conditions, photorespiration is not a problem.

Photorespiration is influenced by high temperature as well as light intensity and accelerating the formation of glycolate and the flow through the photorespiratory pathway.

Photorespiration causes a light-reliant acceptance of O2 and discharge of CO2 and is related to the creation and metabolism of a minute particle named glycolate.

Photosynthesis and photorespiration are two biological processes (in flourishing plants) that can function simultaneously beside each other as photosynthesis gives off oxygen as its byproduct and photorespiration gives off carbon dioxide as its byproduct, and the said gases are the raw material for the said processes.

When the carbon dioxide levels inside the leaf dip to about 50 ppm, RuBisCO begins combining Oxygen with RuBP as an alternative to Carbon dioxide.

The final result of this is that as an alternative to manufacturing 2 molecules of 3C- PGA units, merely one unit of PGA is fashioned with a noxious 2C molecule termed phosphoglycolate.

To purge themselves of the phosphoglycolate the plant takes some steps . Primarily, it instantly purges itself from the phosphate cluster, transforming those units into glycolic acid. After that, this glycolic acid is transferred to the peroxisome and then transformed into glycine. The conversion of glycine into serine takes place in the mitochondria of the plant cell . The serine produced after that is used to create other organic units. This causes a loss of carbon dioxide from the flora as these reactions charge plant’s energy.

Also Read:   Photosynthesis

To avert this procedure, two dedicated biochemical reactions were necessary to evolve in the flora of our world:

Photosynthesis in C4 plants

Plants that propagate in warm, arid climates similar to sugarcane and corn have developed a dissimilar system for carbon dioxide fixation. The structure of the leaves of these plants is dissimilar to that of a normal leaf. They are known to display Kranz anatomy. Dense-walled parenchyma cells termed as bundle sheath cells surround the phloem and xylem of these leaves where the maximum amount of photosynthesis happens.

Also Refer:   The Plant Tissue System

CAM – Crassulacean Acid Metabolism

  This section of flora makes use of a procedure akin to the C4 section apart from the fact that they take carbon dioxide in nocturnal hours and convert it into malic or aspartic acid. The vacuoles of their photosynthetic cells provide a location to store them. As soon as the sun shines these plants shut their stomata and disintegrate the malic acid to keep the carbon dioxide ratio high enough to avert photorespiration. This permits the leaves to have their stomata shut with the intention of preventing withering. This section of flora doesn’t display Kranz anatomy.

Also Read:  Stomata

For more information about the Photorespiration, its process and other related topics, visit us at  BYJU’S Biology.

Important Questions on Photorespiration

Q.1.What is  Photorespiration? Sol.  P hotorespiration  can be defined as the evolution of carbon dioxide(CO 2 ) during photosynthesis.

Q.2.What is  Photosynthesis? Sol.  Photosynthesis is a biological process, which uses light energy (sunlight) to synthesise organic compounds.

Q.3.Which light range is most effective in photosynthesis? Sol. Red light.

Q.4.What is the function of RuBisCO in photorespiration?

Sol.  In photorespiration, RuBisCO catalyses the oxygenation of RuBP to one molecule of PGA and phosphoglycolate.

Q.5.What is the difference between photosynthesis and photorespiration?

Sol. Photosynthesis and photorespiration are different processes. In photosynthesis, carbon dioxide fixation takes place by the RuBisCO, whereas in the photorespiration RuBisCO reacts with oxygen and it competes with the Calvin cycle.

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