NCERT Exemplar Class 11 Biology Solutions Chapter 13 Photosynthesis in Higher Plants

Get Photosynthesis in Higher Plants Class 11 NCERT Exemplar (MCQs)

A variety of questions like MCQs, Short answers, and long answers, along with the required diagrams and graphs, are provided below to help you understand these complex topics easily and effectively, and gain more clarity on the doubts and solve them with ease.

Question:1

Which metal ion is a constituent of chlorophyll?
a. Copper
b. Magnesium
c. Iron
d. Zinc

Answer:

The correct answer is option (b), Magnesium

Explanation- A chlorophyll molecule has a cyclic structure with a ring, and it contains a magnesium atom in the center.

Question:2

Which pigment acts directly to convert light energy to chemical energy?

a. Carotenoid
b. Chlorophyll B
c. Chlorophyll A
d. Xanthophyll

Answer:

The correct answer is option (c), Chlorophyll A

Explanation – Chlorophyll A absorbs the maximum light and therefore directly converts light energy to chemical energy.

Question:3

Which range of wavelength (in nm) is called photosynthetically active radiation (PAR)?

a. 760 -10,000
b. 400 -700
c. 390 -430
d. 100 -390

Answer:

The correct answer is option (b), 400-700nm

Explanation: This range of visible light is called photosynthetically active radiation (PAR) because pigments like chlorophyll absorb light most effectively here, driving photosynthesis.

Question:4

Which light range is least effective in photosynthesis?

a. Red
b. Blue
c. Green
d. Violet

Answer:

The correct answer is option (c). Green

Explanation - The least effective light in photosynthesis is green light. As chlorophyll is present in leaves, the pigment responsible for photosynthesis reflects the green light rather than absorbing it.

Question:5

Chemosynthetic bacteria obtain energy from
a. Organic substances
b. Inorganic chemical
c. Sun
d. Infrared rays

Answer:

The correct answer is option (b). Inorganic chemical

Explanation - These bacteria obtain energy from the oxidation of inorganic chemicals to produce food.

Question:6

Energy required for ATP synthesis in PS II comes from
a. Electron gradient
b. Reduction of glucose
c. Oxidation of glucose
d. Proton gradient

Answer:

The correct answer is option (d), the Proton gradient

Explanation: In PS II, the splitting of water and electron transport creates a proton gradient across the thylakoid membrane, and this gradient drives ATP synthesis through ATP synthase.

Question:7

During the light reaction in photosynthesis, the following are formed.
a. ATP, hydrogen donor, and O₂
b. ATP and sugar
c. ATP, hydrogen, and O₂ donor
d. Hydrogen, O₂, and sugar

Answer:

The correct answer is option (c), ATP, Hydrogen donor, and O₂.

Explanation - During the light reaction of photosynthesis, ATP, hydrogen, and oxygen are formed. Hydrogen and oxygen are by-products of water splitting.

Question:8

Dark reaction in photosynthesis is called so because
a. It does not depend on light energy
b. It cannot occur during daylight
c. It occurs during daylight
d. It can occur in the dark

Answer:

The correct answer is option (a). It does not depend on light energy

Explanation - The "dark reaction" in photosynthesis is called so because it does not directly require light energy to occur, but instead, it uses the energy stored in ATP and NADPH produced during the light-dependent reactions.

Question:9

PEP is the primary CO₂ acceptor in
a. C₃ plants
b. C₄ plants
c. C₂ plants
d. Both C₃ and C₄ plants

Answer:

The correct answer is option (b). C₄ plants

Explanation - PEP is the primary CO₂ acceptor in C₄ plants because it allows for carbon fixation, mainly in environments with low CO₂ concentrations.

Question:10

The splitting of water is associated with
a. Lumen of the thylakoid
b. Photosystem I
c. Both photosystem I and II
d. Inner surface of thylakoid membrane

Answer:

The correct answer is option (d). Inner surface of the thylakoid membrane

Explanation- The splitting of water is associated with the inner thylakoid membrane because the water-splitting complex, part of Photosystem II (PSII), is located on that side, allowing the release of protons and electrons.

Question:11

The correct sequence of the flow of electrons in the light reaction is
a. PSI, ferredoxin, PSII
b. PSI, plastoquinone, cytochromes, PS II, ferredoxin
c. PS II, plastoquinone, cytochromes, PS I, ferredoxin
d. PS I, plastoquinone, cytochromes, PS I, ferredoxin

Answer:

The correct answer is option (c). PS II, plastoquinone, cytochromes, PS I, ferredoxin

Explanation: In the light reaction, electrons released from water first enter PS II, then pass through plastoquinone and the cytochrome complex, move to PS I, and finally reach ferredoxin, which helps in reducing NADP⁺ to NADPH.

Question:12

The enzyme that is found in a C₃ plant is
a. ATP synthase
b. NADP reductase
c. PEP carboxylase
d. RuBP carboxylase

Answer:

The correct answer is option (d). RuBP carboxylase

Explanation - It is the main enzyme that catalyzes the first step of carbon fixation in the C₃ plants.

Question:13

The reaction that is responsible for the primary fixation of CO₂ is catalyzed by
a. PGA synthase
b. RuBP carboxylase and PEP carboxylase
c. RuBP carboxylase
d. PEP carboxylase

Answer:

The correct answer is option (b). RuBP carboxylase and PEP carboxylase

Explanation - PEP carboxylase catalyzes the reaction in C₄ plants, and RuBP carboxylase in C₃ plants.

Question:14

When CO₂ is added to PEP, the first stable product synthesised is
a. Oxaloacetate
b. Pyruvate
c. Glyceraldehyde-3-phosphate
d. Phosphoglycerate

Answer:

The correct answer is option (a). Oxaloacetate

Explanation- Oxaloacetate is the first stable product, and it's a four-carbon compound.

Access the NCERT Exemplar Class 11 Biology Chapter 13- Very Short Answer Questions:

Question:1

a. Is this structure present in animal cells or plant cells?

b. Can these be passed on to the progeny? How?

c. Name the metabolic processes taking place in the places marked (1) and (2).

Answer:

1. This structure is only found in plant cells.

2. Yes, chloroplasts, along with their DNA, can be passed on to progeny because chloroplasts to self-replicate, and this inheritance is generally maternal in most flowering plants.

3. (i) This is the site for the occurrence of the dark reaction.

(ii) Replication of the chloroplast occurs in the location mentioned as (ii).

Question:2

2H₂O → O₂ + 4H⁺ + 4e⁻

Based on the above equation, answer the following question:
a. Where does this reaction take place in plants?
b. What is the significance of this reaction?

Answer:

(a) It occurs in the thylakoid membrane of chloroplasts, mainly within the Photosystem II (PSII) complex.

(b) This reaction, also known as water splitting or photolysis, is an important step in the light-dependent reactions of photosynthesis because oxygen is released in this reaction as a byproduct of photosynthesis and is essential for respiration, and the electrons released from water are used to give energy to the electron transport chain.

Question:3

Cyanobacteria and some other photosynthetic bacteria don’t have chloroplasts. How do they conduct photosynthesis?

Answer:

Cyanobacteria and other photosynthetic bacteria, which do not have chloroplasts, conduct photosynthesis using photosynthetic pigments present in their cell membranes, specifically in internal membranes called thylakoids.

Question:4

A. Breakdown of proton gradient leads to release of ___________

B. NADP reductase enzyme is located on _______

Answer:

A. ATP molecules

B. The outer side of the thylakoid membrane

Question:5

Can girdling experiments be done in monocots? If yes, how? If not, why not?

Answer:

No girdling experiments can be performed on monocots because their vascular bundles are present throughout the stem, making it impossible to remove a continuous ring of bark (phloem) without disturbing the complete vascular system.

Question:6

3CO₂ + 9ATP + 6NADPH + water → Glyceraldehyde 3-phosphate + 9ADP + 6NADP++8P_i

Analyse the above reaction and answer the following question
a. How many molecules of ATP & NADPH are required to fix one molecule of CO₂?
b. Where in the chloroplast does this process occur?

Answer:

(a) 3 molecules of ATP and 2 molecules of NADPH are required to fix one molecule of carbon dioxide.

(b) This reaction occurs in the stroma of the chloroplast.

Question:7

Does moonlight support photosynthesis? Find out.

Answer:

No, moonlight does not support photosynthesis because it does not have the required energy to excite chlorophyll molecules, which is important for the light-dependent reactions of photosynthesis.

Question:8

Some of these terms/ chemicals are associated with the C₄ cycle. Explain
a. Hatch Slack pathway
b. Calvin cycle
c. PEP carboxylase
d. Bundle sheath cells

Answer:

(a) Hatch–Slack pathway is the C₄ pathway of photosynthesis in which CO₂ is initially fixed into a 4-carbon compound (oxaloacetate) in mesophyll cells before being transferred to bundle sheath cells for the Calvin cycle.

(b) Calvin cycle, also called the C₃ cycle, occurs in the stroma of chloroplasts where CO₂ is fixed into a 3-carbon compound (3-PGA) using ATP and NADPH.

(c) PEP carboxylase is the enzyme in mesophyll cells of C₄ plants that fixes CO₂ to phosphoenolpyruvate (PEP), forming oxaloacetic acid, a 4-carbon compound.

(d) Bundle sheath cells are specialized cells surrounding the vascular bundles in C₄ plants, where the Calvin cycle occurs, helping in efficient CO₂ fixation and minimizing photorespiration.

Question:9

Where is NADP reductase enzyme located in the chloroplast? What is the role of this enzyme in proton gradient development?

Answer:

NADP reductase enzyme is located on the outer side of the thylakoid membrane in chloroplasts. It plays an important role in maintaining the proton gradient by reducing NADP⁺ to NADPH, which takes protons from the stroma, thus contributing to the proton gradient.

Question:10

ATPase enzyme consists of two parts. What are those parts? What are those parts? How are they arranged in the thylakoid membrane? Conformational change occurs in which part of the enzyme?

Answer:

The ATPase enzyme consists of two parts: F₀ (integral membrane protein) and F₁ (peripheral membrane protein). F₀ is present in the inner region of the thylakoid membrane, while F₁ lies in the outer region of the thylakoid, and conformational changes occur in the F₁ portion. All the conformational changes occur in the F₁ portion.

Question:11

Which products formed during the light reaction of photosynthesis are used to drive the dark reaction?

Answer:

The products ATP and NADPH formed during the light reaction of photosynthesis drive the dark reaction. These products are used in the formation of glucose, a sugar that provides energy for the cell.

Question:12

What is the basis for designating C₃ and C₄ pathways of photosynthesis?

Answer:

The basis for the designations of C₃ and C₄ pathways in photosynthesis is based on the number of carbon atoms present in the first stable product. C₃ pathways form a 3-carbon compound (3-PGA), while C₄ pathways form a 4-carbon compound, which is oxaloacetate.

Discover the NCERT Exemplar Class 11 Biology Chapter 13- Short Answer Questions

Question:1

Succulents are known to keep their stomata closed during the day to check transpiration. How do they meet their photosynthetic CO₂ requirements?

Answer:

Succulent plants grow in dry conditions. To these plants, they have to close down their stomata during the time to prevent water loss through transpiration, and also, the exchange of gases does not take place.

Thus, plants have developed a mechanism to fix CO₂ during the night in the form of malic acid and release it during the day inside the photosynthetic cells.

Question:2

Chlorophyll a is the primary pigment for the light reaction. What are the accessory pigments? What is their role in photosynthesis?

Answer:

Chlorophyll 'a' is the primary pigment for the light reaction, and the accessory pigments like chlorophyll b, carotenoids, and xanthophylls also help in photosynthesis by absorbing light of different wavelengths and transferring the energy to chlorophyll 'a', and can carry out the supporting process.

Question:3

Does the reaction of photosynthesis, called the ‘dark reaction,’ need light? Explain.

Answer:

Dark reactions of photosynthesis do not directly require light to occur. The dark reactions occur in the day. As a dark reaction does not require light, it doesn't mean it occurs at night; it only requires products of the light reaction, like ATP and NADPH. So, dark reactions indirectly need sunlight but can work without it as well.

Question:4

How are photosynthesis and respiration related to each other?

Answer:

Photosynthesis and respiration are interconnected as photosynthesis uses carbon dioxide and water to produce glucose and oxygen, while respiration uses glucose and oxygen, which is released as a by-product of photosynthesis, to produce carbon dioxide and water. It means both act as the reverse of each other.

Question:5

If a green plant is kept in the dark with proper ventilation, can this plant carry out photosynthesis? Can anything be given as a supplement to maintain its growth or survival?

Answer:

A green plant kept in darkness, even with proper ventilation, cannot perform photosynthesis because sunlight is essential to carry out the process of photosynthesis. To maintain its growth or survival, the plant can be supplemented with sugars along with nutrients and water, but long-term growth is not possible without light.

Question:6

Photosynthetic organisms occur at different depths in the ocean. Do they receive qualitatively and quantitatively the same light? How do they adapt to carry out photosynthesis under these conditions?

Answer:

No, photosynthetic organisms that occur at different ocean depths do not receive the same light, either qualitatively or quantitatively.

But deeper organisms also perform the process of photosynthesis very effectively, as these organisms are adapted to low-light conditions due to the presence of different pigments. These pigments absorb the light at available and different wavelengths.

Question:7

In tropical rainforests, the canopy is thick, and shorter plants growing below it receive filtered light. How are they able to carry out photosynthesis?

Answer:

Plants present in tropical rainforests, where the canopy is thick, despite receiving less amount of light to carry out photosynthesis, because they have adapted themselves to survive in low-light conditions, with changes like large leaves and high chlorophyll units. However, the process slowed down a little bit.

Question:8

What conditions enable RuBisCO to function as an oxygenase? Explain the ensuing process.

Answer:

RuBisCO is an enzyme that has a dual nature. It acts as a carboxylase when the CO₂ concentration is high. But if O₂ concentration increases and CO₂ is low, especially at higher temperatures, it acts as an oxygenase. This leads to photorespiration, where RuBP reacts with oxygen, producing PGA and phosphoglycolate.

Question:9

Why does the rate of photosynthesis decrease at higher temperatures?

Answer:

The rate of photosynthesis decreases at higher temperatures because the enzymes involved in this process require the optimum conditions of temperature to work effectively, but as these conditions change, the rate of photosynthesis sis also affected.

Question:10

Explain how the light reaction of photosynthesis, ATP synthesis, is a chemiosmotic phenomenon.

Answer:

Chemiosmosis is the movement of ions across a semipermeable membrane, down their electrochemical gradient, to produce energy. During the light reaction of photosynthesis, ATP is synthesised, which is a chemiosmotic phenomenon because it involves the movement of protons across the thylakoid membrane, which creates a proton gradient that drives ATP synthesis by ATP synthase.

Question:11

Find out how Melvin Calvin worked out the complete biosynthetic pathway for the synthesis of sugar.

Answer:

Melvin Calvin and his associates discovered the Calvin cycle, which consists of various steps:-

• They used ¹⁴C as a radioactive label to follow the path of photosynthetic carbon fixation. The labelled CO₂ was fed to the algae for short periods.

• The algal cells were killed immediately in boiling alcohol, and radioactivity in various compounds was separated by paper chromatography.

• When algae were exposed to radioactive CO₂ for less than five seconds, the first product that became radioactive was the phosphoglyceric acid.

This is how the Calvin cycle was discovered.

Question:12

Six turns of the Calvin cycle are required to generate one mole of glucose. Explain.

Answer:

Six turns of the Calvin cycle are needed to produce one molecule of glucose because each turn reduces one carbon dioxide molecule, two molecules of NADPH, and 2 molecules of ATP. Glucose is a six-carbon molecule, and thus, six CO₂ molecules are required for the making of one mole of glucose.

Question:13

Answer:

The complete flow chart for cyclic photophosphorylation is given below:

Question:14

In what kind of plants do you come across ‘Kranz’ anatomy? To which conditions are those plants better adapted? How are these plants better adapted than the plants that lack this anatomy?

Answer:

Kranz anatomy, a unique leaf structure, is found in C₄ plants like maize and sugarcane. These plants are better adapted to dry, tropical conditions, where temperature and light intensities are very high. These plants are better adapted because Kranz anatomy helps them to minimize the process of photorespiration and maximize carbon fixation, which also leads to the easy manufacturing of glucose.

Question:15

A process is occurring throughout the day, in the’X’ organism. Cells participate in this process. During this process, ATP, CO₂, and water are evolved. It is not a light-dependent process.
a. Name the process
b. Is it a catabolic or an anabolic process?
c. What could be the raw material of this process?

Answer:

a. The name of the process is respiration

b. The respiration process is a catabolic process.

c. The raw material used in this process is carbohydrates.

Question:16

Tomatoes, carrots, and chilies are red in color due to the presence of one pigment. Name the pigment. Is it a photosynthetic pigment?

Answer:

Tomatoes, Chillies, and Carrots are red due to the presence of a pigment called Lycopene. Lycopene is not a photosynthetic pigment; it's a carotenoid.

Question:17

Why do we believe chloroplasts and mitochondria to be semi-autonomous organelles?

Answer:

Mitochondria and chloroplasts are considered semi-autonomous organelles because they have their own DNA, ribosomes, and protein-synthesizing parts, allowing them to replicate independently and produce some of their own proteins, though they still depend on the cell for other functions.

Question 18:

Observe

a. Which group of plants exhibits these two types of cells?

b. What is the first product of the C₄ cycle?

c. Which enzyme is there in bundle sheath cells and mesophyll cells?

Answer:

a. Bundle sheath cells and mesophyll cells are found in C₄ plants.

b. Oxaloacetic acid, a 4-carbon compound, is the first stable product.

c. PEP carboxylase is present in mesophyll cells, while RuBisCO is present in bundle sheath cells.

Question:19

A cyclic process occurs in a C₃ plant, which is light-dependent and needs O₂. This process does not produce energy; rather, it consumes energy.
a. Can you name the given process?
b. Is it essential for survival?
c. What are the end products of this process?
d. Where does it occur?

Answer:

a. The name of the process is photorespiration.

b. No, it is not important for survival.

c. The end products of this process are CO₂ and water (H₂O₂ is formed as an intermediate in peroxisomes).

d. It occurs in chloroplasts, mitochondria, and peroxisomes.

Question:20

Suppose euphorbia and maize are grown in tropical areas.

a. Which one of them do you think will be able to survive under such conditions?
b. Which one of them is more efficient in terms of photosynthetic activity?
c. What differences do you think are there in their leaf anatomy?

Answer:

a. Euphorbia is a CAM plant. Therefore, it will be able to survive under such conditions.

b. Maize will be more efficient in photosynthesis because it is a C₄ plant.

c. Kranz leaf anatomy is found in maize plants as they are C₄ plants. In contrast, it is absent in Euphorbia, which uses the CAM pathway.

Detailed Answers of Photosynthesis in Higher Plants Class 11 NCERT Exemplar

Question:1

Is it correct to say that photosynthesis occurs only in the leaves of a plant? Besides leaves, what are the other parts that may be capable of carrying out photosynthesis? Justify.

Answer:

No, it's not correct to say that photosynthesis occurs only in the leaves of a plant; while leaves are the main sites to carry out the process, any green part of a plant containing chlorophyll can also photosynthesise, including green stems, branches, and even some roots. For example:

• Green Stems: Plants like cacti have thick and fleshy stems that function as leaves because they contain chlorophyll and chloroplasts for photosynthesis.

• Green Branches: Just like stems, green branches can also do photosynthesis, especially in plants with limited leaf development.

• In some plants, the sepals can also photosynthesise.

Question:2

The entire process of photosynthesis consists of a number of reactions. Where in the cell does each of these take place?
a. Synthesis of ATP and NADPH_____
b. Photolysis of water_______
c. Fixation of CO₂ _______
d. Synthesis of sugar molecule________
e. Synthesis of starch________

Answer:

a. Thylakoid membrane

b. Thylakoid membrane (lumen side for water splitting)

c. Stroma of chloroplast

d. Stroma of chloroplast

e. Stroma of chloroplast (later stored in cytoplasm as starch grains)

Question:3

What property of the pigment is responsible for its ability to initiate the process of photosynthesis? Why is the rate of photosynthesis higher in the red and blue regions of the spectrum of light?

Answer:

The property of pigments, specifically chlorophyll, that initiates the process of photosynthesis is their ability to absorb photons of light and become excited, which allows them to transfer the energy, which is utilized to start the process.

The process of photosynthesis is more efficient in red and blue light because these wavelengths are mostly absorbed by chlorophyll, thus increasing the rate of photosynthesis.

Question:4

What can we conclude from the statement that the action and absorption spectra of photosynthesis overlap? At which wavelength do they show peaks?

Answer:

Action spectrum - It is the graph that shows the rate of photosynthesis at different wavelengths of light.

Absorption spectrum - A graph that shows the amount of light absorbed at different wavelengths of light.

When both the action and absorption spectra overlap, it indicates that the light which is absorbed is utilized for the process of photosynthesis. The peaks of these spectra indicate that chlorophyll a and b are the main photosynthetic pigments.

By looking at the above graph, it is very clear that the action spectrum shows maximum peaks of blue at 430–450 nm and red at 660–680 nm.

Question:5

Under what conditions are C₄ plants superior to C₃?

Answer:

C₄ plants are considered to be superior to C₃ plants. There are several reasons for this, which are provided below:

C₄ plants can respond to higher temperatures and show a higher rate of photosynthesis, while C₃ plants respond to a much lower value of optimum temperature range.

The C₃ and C₄ plants respond differently to CO₂ concentrations. At low concentrations, C₄ plants can carry out the process of photosynthesis, but C₃ plants cannot do so.

C₄ plants can perform photosynthesis even when their stomata are almost closed, but C₃ plants can perform photosynthesis only when their stomata are open.

Question:6

a. What does the action spectrum indicate? How can we plot an action spectrum? Explain with an example.
b. How can we derive an absorption spectrum for any substance?
Chlorophyll a is responsible for the light reaction of photosynthesis. Why do the action spectrum and absorption spectrum not overlap?

Answer:

(a) An action spectrum indicates the effectiveness of different wavelengths of light in the process, such as photosynthesis, by plotting the graph of the rate of photosynthesis against the wavelength of light.

To plot an action spectrum, firstly, we need to measure the amount of oxygen released during the process of photosynthesis on the y-axis under different wavelengths of light and then plot these rates against the corresponding wavelengths, which are present on the x-axis.

(b) An absorption spectrum can be plotted by passing a beam of light through a sample and measuring the amount of light that is absorbed at each wavelength. The obtained data is then plotted on a graph, with the given wavelength on the x-axis and how much light is absorbed on the y-axis.

(c) Action and absorption spectra don’t perfectly overlap because accessory pigments (chlorophyll b, carotenoids, xanthophylls) absorb additional light that contributes to the action spectrum.

Question:7

What are the important events and end products of the light reaction?

Answer:

The light reaction consists of various important events, which are given below:

1- Light Absorption: The pigments present in the leaves, such as chlorophyll and other accessory pigments, absorb the light at different wavelengths and then excite the electrons from lower energy levels to higher energy levels.

2-Water Splitting (Photolysis): Absorbed light energy is utilized to break down the molecule of water into oxygen, hydrogen ions, and electrons.

3- ATP Synthesis (Photophosphorylation): The proton gradient is used in the formation of ATP from ADP through synthetase.

4- NADPH formation- Electrons released from the electron transport chain are used to produce NADPH.

The end products of the light reaction are ATP, NADPH, and oxygen molecules.

Question:8

Answer:

The process of cyclic phosphorylation is depicted in this diagram.

Question:9

Why is the RuBisCO enzyme more appropriately called RUBP Carboxylase -Oxygenase, and what important role does it play in photosynthesis?

Answer:

RuBisCO enzyme shows a dual nature as

Carboxylation: When there is a large concentration of carbon dioxide, RuBisCO binds with that and acts as a carboxylase.

Oxygenation: RuBisCO possesses an affinity for oxygen, depending on the concentration, and can work accordingly.

Therefore, it is often called RUBP Carboxylase-Oxygenase compound.

Importance of Photosynthesis:

• Carbon Fixation: RuBisCO is the enzyme that fixes atmospheric CO₂ into organic molecules, due to which it initiates the entire food chain.

• Calvin Cycle: RuBisCO's carboxylation activity is the first step in the Calvin cycle, where CO₂ is converted into sugar.

• Photorespiration: This enzyme also plays a role in protecting plants from stress and in the recycling of carbon.

Question:10

What special autonomous features are displayed by leaves of C₄ plants? How do they provide an advantage over the structure of C₃ plants?

Answer:

C₄ plants show a different type of leaf structure where the vascular bundles are surrounded by cells with large chloroplasts, which helps to concentrate CO₂, known as Kranz anatomy, which is not present in the C₃ plants.

Advantages over C₃ Plants:

• Higher Photosynthetic Rates: C₄ plants can maintain higher photosynthetic rates, especially in hot and dry conditions, due to their ability to avoid photorespiration, which C₃ plants fail to do.

• Water Conservation: By minimizing photorespiration, C₄ plants can conserve water more effectively where less water is present, as they can close their stomata, reducing photosynthetic efficiency.

• Adaptation to Hot Environments: The Kranz anatomy and the C₄ pathway allow C₄ plants to survive in environments where C₃ plants struggle in hot, arid regions.

Question:11

Name the two important enzymes of the C₃ and C₄ pathway, respectively. What important role do they play in fixing CO₂?

In the C₃ pathway, the key enzyme for CO₂ fixation is RuBisCO, which is known as RUBP Carboxylase Oxygenase, while in the C₄ pathway, it's PEP carboxylase. RuBisCO fixes CO₂ to RuBP, and PEP carboxylase fixes CO₂ to PEP.

In C₃ plants, RuBisCO (Ribulose-1,5-bisphosphate carboxylase-oxygenase) is the main enzyme that is responsible for carbon fixation.

PEP carboxylase is the key enzyme in the C₄ pathway. It combines with carbon dioxide to result in the formation of a 4-carbon compound called OAA or oxaloacetic acid. This is further converted into carbon dioxide.

Question:12

Why is RuBisCO enzyme the most abundant enzyme in the world?

Answer:

RuBisCO is the most abundant enzyme on Earth because it's the main enzyme responsible for carbon fixation during photosynthesis. The enzyme is present in all plants performing photosynthesis, which is an important process essential for plant growth.

Also, check the NCERT Books and NCERT Syllabus here.

• NCERT Books Class 11 Biology

• NCERT Syllabus Class 11 Biology

• NCERT Books Class 11

• NCERT Syllabus Class 11

Approach to Solve Questions of NCERT Exemplar Class 11 Biology Chapter 13

Solving questions is important because it helps students break down big topics like photosynthesis into smaller parts. It also guides them to focus on diagrams, key terms, and stepwise processes.

• Read the NCERT and Exemplar solutions to understand each step of photosynthesis, like light and dark reactions.

• Practice drawing diagrams of chloroplast structure, light reactions, and the Calvin cycle.

• Memorise key terms like Photosystem I and II, RuBisCO, and ATP/NADPH formation.

• Solve questions given in NCERT Exemplar Class 11 Biology Solutions Chapter 13, focusing on application-based and reasoning questions.

• Revise the differences between C₃, C₄, and CAM pathways, and understand photorespiration.

Also, read the NCERT Solution subject-wise

• NCERT Solutions for Class 11 Maths

• NCERT Solutions for Class 11 Physics

• NCERT Solutions for Class 11 Chemistry

• NCERT Solutions for Class 11 Biology

Main topics of NCERT Exemplar Class 11 Biology Chapter 13

This chapter explains how photosynthesis takes place in higher plants and what steps and reactions are involved throughout the process.

• Structure of Chloroplast

• Photosynthetic Pigments

• Light and Dark Reactions

• Cyclic and Non‑cyclic Photophosphorylation

• Calvin Cycle (C₃ Pathway)

• C₄ and CAM Pathways

• Photorespiration

• Factors Affecting Photosynthesis (light intensity, CO₂, temperature)

NCERT Exemplar Class 11 Solutions for Other Subjects

• NCERT Exemplar Class 11 Mathematics Solutions
• NCERT Exemplar Class 11 Chemistry Solutions
• NCERT Exemplar Class 11 Physics Solutions

Important Question from Photosynthesis in Higher Plants Class 11 NCERT Exemplar

This chapter is important because NEET often asks questions about Photosynthesis, focusing on how plants make food. The question given below helps the students to understand the key concepts of this chapter. For more such questions, students can refer to the NCERT Exemplar Class 11 Biology Solutions Chapter 13.

Question 1. In which part of the chloroplast does the light reaction of photosynthesis take place?

Options:
A. Stroma
B. Grana
C. Outer membrane
D. Inner membrane

Answer: The correct answer is option (B), Grana.

Explanation:
The light reaction of photosynthesis takes place in the grana of the chloroplast. Grana are stacks of thylakoid membranes where chlorophyll and other pigments capture light energy. The captured light energy is used for the process of photolysis, which releases oxygen and generates molecules of ATP and NADPH. These molecules are important to carry out the process of the light reaction.

Must Read NCERT Notes subject-wise

• NCERT Notes for Class 11 Maths

• NCERT Notes for Class 11 Physics

• NCERT Notes for Class 11 Chemistry

• NCERT Notes for Class 11 Biology

NCERT Exemplar Class 11 Biology Solutions Chapter Wise

The chapter-wise links are given below: