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NCERT Solutions for Class 11 Biology Chapter 11 Photosynthesis in Higher Plants
The NCERT Solutions for Class 11 Biology Chapter 11 Photosynthesis in Higher Plants explains how photosynthesis occurs, which supports life on Earth. Difficult topics like light reactions, the Calvin cycle, and photorespiration are explained clearly, along with the role of pigments that capture light energy. Flowcharts and diagrams are added so that students can easily learn the sequence of the processes. Through NCERT Solutions, students can improve their understanding and strengthen their weak areas.
This Story also Contains
- Download Photosynthesis in Higher Plants Class 11 Questions and Answers PDF
- Access Class 11 Biology Chapter 11 Photosynthesis in Higher Plants Question Answer
- Approach to Solve Photosynthesis in Higher Plants Class 11 Question Answer
- Main Topics of Class 11 Biology Chapter 11 Photosynthesis in Higher Plants
- Important Questions of NCERT Class 11 Biology Chapter 11
- What Students Learn from Photosynthesis in Higher Plants NCERT Solutions?
- Why Class 11 Biology Chapter 11 Photosynthesis in Higher Plants NCERT Solutions are Important?
- What Extra Should Students Study Beyond the NCERT for NEET?
- Chapter-Wise NCERT Solutions for Class 11 Biology
The Photosynthesis in Higher Plants Class 11 question answer tells us about how food is prepared. Plants use sunlight, water, and carbon dioxide to prepare food. If students are facing difficulty in learning the concepts, they are at the right place. The Photosynthesis in Higher Plants Class 11 questions and answers PDF also highlight the differences between C3 and C4 pathways, making it easier to compare how plants adapt to different conditions. The NCERT Solutions for Class 11 Biology are a valuable resource for performing well in school exams as well as in competitive exams like NEET.
Download Photosynthesis in Higher Plants Class 11 Questions and Answers PDF
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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Access Class 11 Biology Chapter 11 Photosynthesis in Higher Plants Question Answer
All the questions given in the textbook are explained in simple and clear language. Practising the Class 11 Biology Chapter 11 Photosynthesis in Higher Plants question answer 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.
- External appearance cannot be trusted: Leaf size and shape may be the same in both forms.
- Internal structure is the key: You must examine the anatomy of the leaf to identify the type.
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.
- C4 plants possess a distinct cell arrangement to effectively capture carbon dioxide.
- C4 plants alone possess Kranz anatomy: Efficient fixation of carbon is permitted.
- Different structures of the cells: The Chloroplast arrangement between the two groups is quite different.
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:
- Role of chlorophyll a: It is the primary pigment for the absorption of light energy and starting the process of photosynthesis by donating electrons to be utilised in energy formation.
- Process of accessory pigments and chlorophyll b: Chlorophyll b helps in the absorption of other wavelengths of light and transfers that energy to chlorophyll a, but is unable to carry out its vital function.
Thus, in the absence of chlorophyll a, there cannot be photosynthesis, even with the presence of chlorophyll b.
- Chlorophyll a is required for photosynthesis: No chlorophyll a = no photosynthesis.
- Chlorophyll b is helpful but can't replace chlorophyll a's role: It helps to trap light but doesn't initiate the process.
Answer:
When leaves are stored in the dark, they tend to become yellow or pale green for several reasons:
- Degradation of chlorophyll: Chlorophyll needs light to be produced; in the absence of light, it begins to break down. When chlorophyll degrades, the green colour disappears.
- Exposure of accessory pigments: When chlorophyll is reduced, other pigments such as carotenoids are exposed, which causes leaves to turn yellow.
- This process shows how important light is in keeping healthy green leaves.
- Chlorophyll breaks down in the dark, causing yellowing.
- Accessory pigments such as carotenoids become apparent, adding to the yellow colour.
Answer:
Shaded leaves are darker green than sun-exposed leaves for several reasons:
- Chloroplast orientation and packing: Chloroplasts in shaded places can be packed more densely or have a different orientation within mesophyll cells to capture more light.
- Reduced photo-oxidation in shade: In intense sunlight, some chlorophyll can be damaged or oxidised; however, shaded leaves have more intact chlorophyll since they receive milder light.
- Therefore, leaves that are shaded tend to be darker green because they have healthier chlorophyll.
- Increased chlorophyll in shaded leaves makes the colour darker.
- Lower damage from excessive sunlight preserves levels of chlorophyll.
(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. |
Approach to Solve Photosynthesis in Higher Plants Class 11 Question Answer
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.
- Practising the exemplar questions will also give an idea of the chapter. For better revision, students can refer to the Class 11 Biology Photosynthesis in Higher Plants question answer.
NCERT Solutions for Class 11: Subject-wise
Main Topics of Class 11 Biology Chapter 11 Photosynthesis in Higher Plants
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
Pigments Involved in 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)
Photorespiration
Factors Affecting Photosynthesis
Importance of Photosynthesis
Important Questions of NCERT Class 11 Biology Chapter 11
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
- Dark respiration is higher.
- Dark respiration is lower.
- Photorespiration is present.
- Photorespiration is absent.
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
- more than the ground state of the pigment molecule.
- equal to that of the pigment molecule's excited state.
- more than that of the ground state but less than that of the excited state of the pigment molecule.
- equal to the energy gap between the ground state energy and the excited state energy.
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?
- Carotenoid
- Chlorophyll B
- Chlorophyll A
- Xanthophyll
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
- It does not depend on light energy.
- It cannot occur during daylight.
- It occurs during daylight.
- It can also occur in the dark.
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
- 3-phosphoglyceric acid
- Oxaloacetic acid
- Phosphoenol pyruvate
- Malic acid
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
- Stroma
- Outer thylakoid membrane
- Inner thylakoid membrane
- Lumen side of the thylakoid membrane
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:
- H⁺ (accumulate in the lumen)
- e⁻ (replace lost electrons in PSII)
- O₂ (released)
Question 8: Which of the following is the correct statement regarding RuBisCO?
- It is the most abundant enzyme in animals.
- It has a higher affinity for oxygen than carbon dioxide.
- It catalyses both carboxylation and oxygenation reactions.
- It is present only in C4 plants.
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?
- Light intensity
- Carbon dioxide concentration
- Oxygen concentration
- Water availability
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.
Check the NCERT Books and NCERT Syllabus here:
What Students Learn from Photosynthesis in Higher Plants NCERT Solutions?
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.
Why Class 11 Biology Chapter 11 Photosynthesis in Higher Plants NCERT Solutions are Important?
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.
- Class 11 Biology Chapter 11 Photosynthesis in Higher Plants NCERT Solutions describe the structure and role of chloroplasts, photosynthetic pigments, and other photosystems.
- The complex process of the Calvin cycle is well-explained in the solutions, making it an important resource.
- Students also learn the difference between the C3, C4, and CAM pathways by using the solutions.
- The step-by-step solutions and well-labelled diagrams make it easier for them to remember the important reactions, electron transport, and energy conversions.
- Various questions related to the photosynthesis chapter are frequently asked in the NEET and other competitive exams.
What Extra Should Students Study Beyond the NCERT for NEET?
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:
Chapter-Wise NCERT Solutions for Class 11 Biology
Frequently Asked Questions (FAQs)
Q: What is photosynthesis in higher plants?
A:
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.
Q: What are the two stages of photosynthesis?
A:
The two stages of photosynthesis explained in the NCERT Solutions Class 11 Biology Chapter 11 Photosynthesis in Higher Plants are:
- Light-dependent reactions (Light reactions) take place in the thylakoid membranes and yield ATP and NADPH.
- Light-independent reactions (Calvin cycle) happen in the stroma and incorporate ATP and NADPH in the production of glucose.
Q: What is the difference between cyclic and non-cyclic photophosphorylation?
A:
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.
Q: How does the Calvin cycle work in plants?
A:
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.
Q: What is the role of chlorophyll in photosynthesis?
A:
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.
Q: What are the products of the light reaction in photosynthesis?
A:
The light reaction yields ATP, NADPH, and oxygen. ATP and NADPH are utilized in the Calvin cycle, whereas oxygen is released into the atmosphere.
Q: What is photorespiration and why is it considered a wasteful process?
A:
Photorespiration occurs when oxygen binds to RuBisCO instead of carbon dioxide, reducing photosynthesis efficiency. It wastes energy and carbon, making the process less effective.
Q: How do CAM plants differ from C3 and C4 plants?
A:
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.
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