NCERT Solutions of Class 11 Biology Chapter 11 Photosynthesis in Higher Plants explains the meaning, process and importance of photosynthesis. It covers high-yield topics such as light reaction, dark reaction, C3 cycle, C4 pathway and phtorespiration with the help of well lablled diagram and flowcharts. The Photosynthesis in Higher Plants NCERT Class 11 PDF download helps students revise concepts quickly and improve their conceptual understanding.
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This article covers Class 11 Biology Chapter 11 Photosynthesis in Higher Plants NCERT all textbooks questions and answers. It includes a free PDF curated by subject experts with step-by-step explanations of each concept in an easy-to-understand way. The Photosynthesis in Higher Plants Class 11 NCERT Solutions PDF also highlight the differences between C3 vs C4 pathways, making it easier to compare how plants adapt to different conditions.
Photosynthesis is how plants make food using sunlight. Some topics can be confusing, but with easy solutions, students can understand step by step. Students can download the Photosynthesis in Higher Plants Class 11 questions and answers PDF, which follows the latest NCERT guidelines closely.
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All the questions given in the textbook are explained in simple and clear language. Practising the NCERT Solutions for Class 11 Biology Chapter 11 Photosynthesis in Higher Plants question answers helps students to improve their basic knowledge.
Q1. By looking at a plant externally, can you tell whether a plant is C3 or C4? Why and how?
Answer:
No, you can't determine whether a plant is C3 or C4 by simply observing it from the outside. Both plants can have the same leaf size and shape. For instance, wheat (a C3 plant) and maize (a C4 plant) can appear the same, but they employ different mechanisms for photosynthesis. To properly identify them, you must observe their internal structures.
Q2. By looking at the internal structure of a plant, can you tell whether a plant is C3 or C4? Explain.
Answer:
The main internal feature that helps differentiate C3 and C4 plants is known as Kranz anatomy.
This can be observed under a microscope. Here’s how they differ:
| Feature | C3 Plants | C4 Plants |
|---|---|---|
| Bundle Sheath Cells | Small with fewer chloroplasts | Larger with chloroplasts that lack grana |
| Mesophyll Cells | Organised into palisade and spongy layers | Arranged in concentric circles around vascular bundles |
| Chloroplasts | Contain grana | Do not contain grana in bundle sheath cells |
Answer:
C4 plants are very productive due to their special mechanism of concentrating carbon dioxide, which increases the efficiency of photosynthesis.
Concentration of CO2: In mesophyll cells, CO2 is fixed into a 4-carbon compound, which is transported to bundle sheath cells and released CO2 there, ensuring a constant supply.
Lower photorespiration: With high CO2 levels and low O2 in bundle sheath cells (due to reduced PSII activity), RuBisCO acts mainly as a carboxylase, preventing energy loss.
Thus, even though only bundle sheath cells perform the Calvin cycle, the CO2 concentrating mechanism makes C4 plants more efficient and productive than C3 plants.
Q4. RuBisCO is an enzyme that acts both as a carboxylase and oxygenase. Why do you think RuBisCO carries out more carboxylation in C4 plants?
Answer:
RuBisCO can bind to both CO2 and O2. In C4 plants, conditions inside bundle sheath cells favour carboxylation:
High CO2 concentration: CO2 is delivered from mesophyll cells and released near RuBisCO in bundle sheath cells.
Low O2 levels: Bundle sheath cells have little PSII activity, so oxygen evolution is minimal.
This special environment ensures RuBisCO works mainly as a carboxylase, thereby increasing photosynthetic efficiency in C4 plants.
Answer:
Plants with chlorophyll b alone cannot perform photosynthesis effectively because chlorophyll a plays a vital role in the process:
Thus, in the absence of chlorophyll a, there cannot be photosynthesis, even with the presence of chlorophyll b.
Answer:
When leaves are stored in the dark, they tend to become yellow or pale green for several reasons:
Answer:
Shaded leaves are darker green than sun-exposed leaves for several reasons:
(a) At which point/s (A, B, or C) in the curve is light a limiting factor?
Answer:
At A point, light is the limiting factor because the rate of photosynthesis is minimal here.
(b) What could be the limiting factor/s in region A?
Answer:
In region A, light is a limiting factor. The other limiting factors in this region can be temperature, CO2 and H2O.
(c) What do C and D represent on the curve?
Answer:
C represents a stage beyond which light is not a limiting factor, and D is the line beyond which the intensity of light does not affect the rate of photosynthesis.
Q9. Give a comparison between the following:
(a) C3 and C4 pathway
Answer:
C3 Pathway | C4 Pathway |
There are plants in which the first stable product after the carbon assimilation is a 3-carbon molecule, i.e., 3-phosphoglyceric acid. These plants are called C3 plants, while the pathway for carbon assimilation in them is called the C3 pathway. | In the plants found in the tropical area, the first stable product after carbon assimilation is a 4-carbon molecule or oxaloacetic acid, instead of a 3-carbon compound. These plants are called C4 plants, and the pathway of carbon fixation is called the C4 pathway. |
The cells involved are mesophyll cells. | The cells involved are mesophyll cells and bundle sheath cells |
Most common in plants worldwide. | It is seen in tropical plants. |
RuBisCO acts directly in mesophyll cells. | PEP carboxylase in mesophyll; RuBisCO in bundle sheath. |
Q9. Give a comparison between the following:
(b) Cyclic and non-cyclic photophosphorylation
Answer:
Cyclic photophosphorylation | Non-cyclic photophosphorylation |
Only photosystem I is involved in cyclic photophosphorylation | Both photosystems I and II are involved in non-cyclic photophosphorylation |
The active reaction centre is P700 | The active reaction centre is P680 |
Electron transportation occurs in a cyclic manner | Electron transport occurs in a non-cyclic manner |
Oxygen evolution does not occur | Oxygen is released as a by-product |
Only ATP is produced | Both ATP and NADPH are produced |
Q9. Give a comparison between the following:
(c) Anatomy of a leaf in a C3 and a C4 plant
Answer:
Anatomy of a leaf in C3 plants | Anatomy of a leaf in C4 plants |
Bundle sheath cells are absent. | Bundle sheath cells are present around the vascular bundles. |
RuBisCO is found in mesophyll cells. | RuBisCO is found in bundle sheath cells. |
Plants do not possess 'Kranz' anatomy of leaves. | Leaves show Kranz anatomy. |
Chloroplasts are of a single type only, | Chloroplasts are dimorphic. The chloroplasts of bundle sheath cells are larger and arranged centripetally. |
Mesophyll cells have intercellular spaces. | Mesophyll cells do not have intercellular spaces. |
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The student should start by thoroughly understanding the concepts like light reactions, the Calvin cycle, and photorespiration.
Diagrams and flowcharts can be used to have a visual understanding of the topics. Processes such as the Z scheme and cyclic vs non-cyclic photophosphorylation should be studied.
Focus should be given to the role of pigments and the factors affecting photosynthesis. Factors are well explained in the Class 11 Biology Chapter 11 Photosynthesis in Higher Plants question answer.
The NCERT Solutions for Class 11 are easy to understand and are presented in simple language. This encourages students to know the major concepts and perform well in exams.
NCERT Solutions for Class 11: Subject-wise
Photosynthesis in Higher Plants explains how green plants capture light energy and convert it into chemical energy important for life. This chapter helps students understand the mechanisms, pathways, and factors affecting photosynthesis.
What is Photosynthesis?
Site of Photosynthesis
Light Reaction (Photochemical Phase)
Electron Transport Chain
Photophosphorylation (Cyclic and Non-cyclic)
Dark Reaction (Calvin Cycle)
C3 Pathway
C4 Pathway (Hatch and Slack Pathway)
Importance of Photosynthesis
Below are some of the important questions from the chapter, along with the detailed solutions. Referring to the NCERT Solutions for Class 11 Biology Chapter 11 Photosynthesis in Higher Plants helps students to know how to write answers in exams.
Question 1: What is the correct sequence of the flow of electrons in the light reaction?
Answer:
In the light reaction, the proper order of electron flow is
PSII → Plastoquinone (PQ) → Cytochrome b6f → Plastocyanin (PC) → PSI → Ferredoxin → NADP⁺
Water photolysis: At photosystem II (P680), light energy excites electrons, and the lost electrons are replaced by those obtained from the splitting of water into H⁺, e⁻, and O2.
Electron transport: The electrons move through carriers (PQ, Cyt b6f, PC, PSI, and Fd), releasing energy for ATP formation.
NADPH formation: Finally, electrons reduce NADP⁺ to NADPH with the help of ferredoxin.
Question 2: The CO2 compensation point for C3 plants is greater than for C4 plants because in C3 plants
Answer: The correct answer is option (c). Photorespiration is present.
Explanation: The CO2 compensation point for C3 plants is higher (greater) than that of C4 plants because C3 plants undergo photorespiration.
Photorespiration is a process that occurs in C3 plants when the enzyme Rubisco, which is involved in carbon fixation, binds to oxygen instead of carbon dioxide. This results in the release of carbon dioxide and the consumption of energy and fixed carbon.
Question 3: Upon absorption of a photon, a chlorophyll molecule gets converted to its excited state when the energy of the photon is
Answer: The correct answer is option (d), equal to the energy gap between the ground state energy and the excited state energy.
Explanation: When a chlorophyll molecule absorbs a photon, it can be promoted to an excited state. The energy required to promote the chlorophyll molecule from its ground state to the excited state corresponds to the energy gap between these two states.
Question 4: Which pigment acts directly to convert light energy to chemical energy?
Answer: The correct answer is option (c), Chlorophyll A
Explanation: Chlorophyll is a pigment that is essential to photosynthesis and is responsible for the highest amount of light absorption. The blue (about 430 nm) and red (approximately 662 nm) portions of the spectrum are where this pigment absorbs light the best. Chlorophyll a quickly transforms light energy into chemical energy because it can directly participate in the photochemical events of photosynthesis.
Question 5: The Dark reaction in photosynthesis is called so because
Answer: The correct answer is option (a). It does not depend on light energy.
Explanation: The Light reaction occurs due to the presence of light, when the splitting of water molecules can take place. This results in the formation of ATP. The entire reaction is termed a light reaction. However, further steps do not depend on the presence of light, and hence the process is termed a dark reaction. This does not indicate whether the process occurs in the dark or during the daytime.
Question 6: In C4 plants, the first stable product of carbon fixation is
Answer: The correct answer is option (b), Oxaloacetic acid
Explanation:
In C4 plants, carbon dioxide is initially fixed in the mesophyll cells by the enzyme PEP carboxylase, which combines CO2 with phosphoenol pyruvate (PEP). This forms oxaloacetic acid (OAA), a 4-carbon compound - hence the name C4 pathway. OAA is then usually converted to malate or aspartate and transported to bundle-sheath cells for the Calvin cycle.
Question 7: The enzyme responsible for the photolysis of water in photosynthesis is located in the
Answer: The correct answer is option (d), Lumen side of the thylakoid membrane
Explanation:
The splitting of water (photolysis) takes place in Photosystem II, where the oxygen-evolving complex (OEC) is located. This complex is present on the inner side of the thylakoid membrane facing the lumen. Here, water is split into:
Question 8: Which of the following is the correct statement regarding RuBisCO?
Answer: The correct answer is option (c). It catalyses both carboxylation and oxygenation reactions.
Explanation:
RuBisCO (Ribulose-1,5-bisphosphate carboxylase/oxygenase) is a key enzyme of the Calvin cycle. It can bind to both CO₂ and O₂. When it binds to CO₂, carboxylation occurs, leading to sugar formation. When it binds to O₂, oxygenation occurs, resulting in photorespiration. This dual nature of RuBisCO makes photosynthesis less efficient in C3 plants.
Question 8: Which of the following factors does NOT directly affect the rate of photosynthesis?
Answer: The correct answer is option (c). Oxygen concentration.
Explanation:
The rate of photosynthesis is directly influenced by light intensity, carbon dioxide concentration, and water availability. Oxygen concentration does not directly control the rate of photosynthesis, although high oxygen levels can indirectly affect it by increasing photorespiration in C3 plants.
Living organisms depend on plants for food and oxygen. This chapter explains how plants trap light energy and convert it into chemical energy and prepare food.
Students learn about the light reaction process, including photophosphorylation and the role of pigments.
The Photosynthesis in Higher Plants Class 11 question answer explains the Calvin cycle and how carbon dioxide is fixed.
Learners also understand factors affecting the rate of photosynthesis, such as light intensity, CO2 concentration, and temperature.
Students explore the process of photorespiration and its significance in plant metabolism.
The Class 11 Biology Photosynthesis in Higher Plants question answer describe the differences between the C3 and C4 pathways in plants.
Photosynthesis in Higher Plants is an important chapter as it explains how plants convert light energy into chemical energy to survive. Different cycles that take place during photosynthesis, and the factors that affect this process, are all included in this chapter.
Studying concepts beyond the NCERT will help in attaining conceptual clarity for the NEET exam. The NCERT Solutions for Class 11 Biology Chapter 11 Photosynthesis in Higher Plants help students to answer application-based questions. Some extra concepts that can be studied are:
Below are the chapter-wise solutions that provide detailed explanations, step-by-step answers, and diagrams to help students prepare for exams and improve their foundation for competitive exams like NEET.
The updated NCERT Books Class 11 Biology and the complete NCERT Syllabus Class 11 Biology are provided below for direct access.
Frequently Asked Questions (FAQs)
Higher plant photosynthesis is the process by which green plants utilize sunlight, carbon dioxide, and water to produce food. In this process, oxygen is also released as a waste product. This process is explained in detail in the NCERT Solutions for Class 11 Biology Chapter 11 Photosynthesis in Higher Plants.
The two stages of photosynthesis explained in the NCERT Solutions Class 11 Biology Chapter 11 Photosynthesis in Higher Plants are:
Only Photosystem I is involved in cyclic photophosphorylation, which makes ATP but neither NADPH nor oxygen.
Both Photosystems I and II are involved in non-cyclic photophosphorylation to produce ATP, NADPH, and oxygen.
The Calvin cycle occurs in the chloroplast stroma. It makes use of light reaction ATP and NADPH to fix the carbon dioxide and form glucose.
Chlorophyll is the pigment in plants which is green. It assists in trapping light energy, which helps in the production of food using water and carbon dioxide.
The light reaction yields ATP, NADPH, and oxygen. ATP and NADPH are utilized in the Calvin cycle, whereas oxygen is released into the atmosphere.
Photorespiration occurs when oxygen binds to RuBisCO instead of carbon dioxide, reducing photosynthesis efficiency. It wastes energy and carbon, making the process less effective.
CAM plants take in carbon dioxide during the night and store it to be used during the day. This is an adaptation that enables them to live in arid conditions by minimizing water loss.
A block of mass 0.50 kg is moving with a speed of 2.00 ms-1 on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is
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An athlete in the olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range
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Option 4)
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A particle is projected at 600 to the horizontal with a kinetic energy . The kinetic energy at the highest point
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In the reaction,
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How many moles of magnesium phosphate, will contain 0.25 mole of oxygen atoms?
| Option 1)
0.02 |
Option 2)
3.125 × 10-2 |
| Option 3)
1.25 × 10-2 |
Option 4)
2.5 × 10-2 |
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