NCERT Solutions For Class 11 Biology Chapter 13 Photosynthesis In Higher Plants

Class 11 Biology Chapter 13 Photosynthesis In Higher Plants

NCERT Solutions For Class 11 Biology Chapter 13 Photosynthesis In Higher Plants in this step-by-step answer guide. In some of State Boards and CBSE schools, students are taught thru NCERT books. As the chapter comes to an end, students are requested few questions in an exercising to evaluate their expertise of the chapter. Students regularly want guidance managing those NCERT Solutions. It’s most effective natural to get stuck withinside the exercises while solving them so that you can assist students score higher marks, we’ve provided step by step NCERT answers for all exercises of Class eleven Biology so you can are looking for assist from them. Students should solve those exercises carefully as questions withinside the final exams are requested from those, so these exercises immediately have an impact on students’ final score. Find all NCERT Solutions for Class eleven Biology below and prepare in your tests easily.

NCERT Solutions For Class 11 Biology Chapter 13 Photosynthesis In Higher Plants

Class 11 Biology Chapter 13 Photosynthesis In Higher Plants


Exercise Questions Page No – 224-225

1. By looking at a plant externally can you tell whether a plant is C3 or C4 ? Why and how?


Though plants which are adapted to dry tropical climate have the Cpathway, they do not show any external morphologic characteristics. Hence it is not possible to say whether the plant is C3 and C4 by looking at its external appearance.

2. By looking at which internal structure of a plant can you tell whether a plant is C3 or C4 ? Explain.


Leaves of C4 plants have kranz anatomy which makes them different than Cplants. Cplants also have specialised cells called a bundle sheath cell which surround the vascular bundles. Every cell of the bundle sheath has chloroplasts. The mesophyll cells of leaves do not differentiate into the spongy and palisade parenchyma possessing less intercellular spaces while there is normal occurrence of chloroplasts in the mesophyll cells. But in Cplants, the bundle shealth does not exhibit chloroplast and the mesophyll cells of the leaves are differentiated into the spongy and palisade parenchyma. Hence by examining the internal structure we can tell whether the plant is C3 or C4.

3. Even though a very few cells in a C4 plant carry out the biosynthetic – Calvin pathway, yet they are highly productive. Can you discuss why?


Plant productivity can be estimated by the rate at which photosynthesis takes place. The amount of carbon dioxide in a plant is directly proportional to the rate of photosynthesis. In Cplants, very few of the cells carry out the biosynthetic pathway yet they are highly productive for the following reasons.

  • They have a mechanism that increases the COconcentration at the site of enzyme.
  • Mesophyll cells are broken down in the bundle sheath cells that results in CO2 release which inturn increases the intracellular CO2 concentration .
  • Rubisco functions as a carboxylase minimizing the oxygenase activity.
  • Increase in photosynthesis make Cplants more productive.

4. RuBisCO is an enzyme that acts both as a carboxylase and oxygenase. Why do you think RuBisCO carries out more carboxylation in C4 plants?


The affinity of RUBISCO is much higher than its affinity for Oxygen. It is the concentration of Oxygen and CO2 that determines the binding of the enzyme. Mesophyll cells of C4 plants lack this enzyme but are found in the bundle sheath cells that girdle the vascular bundles where the Calvin cycle occurs.

RuBisco functions as oxygenase when the concentration of Oxygen is higher and it acts as carboxylase when the concentration of CO2 is high. In the mesophyll cells, the primary carbon dioxide acceptor is a three carbon compound – phosphoenol pyruvate which is converted into a four-carbon compound, oxaloacetic acid or OAA. This is converted further into malic acid which is transported to the bundle-sheath cells where it undergoes decarboxylation and carbon fixation takes place through the Calvin cycle which prevents RuBisCo to serve as an oxygenase.

5. Suppose there were plants that had a high concentration of Chlorophyll b, but lacked chlorophyll a, would it carry out photosynthesis? Then why do plants have chlorophyll b and other accessory pigments?


In the absence of chlorophyll-a photosynthesis will not take place because chlorophyll-a is a reaction centre responsible for the conversion of solar energy into chemical energy. Although chlorophyll is the primary pigment that traps sunlight but accessory pigments like chlorophyll-b, xanthophylls and carotenoids also absorb sunlight and transfer energy to chlorophyll-a.

6. Why is the colour of a leaf kept in the dark frequently yellow, or pale green? Which pigment do you think is more stable?


Chlorophyll fails to absorb the energy in the absence of light; hence it loses stability to give the leaf yellow colouration. This proves that carotenoids which imparts yellow color is more stable.

7. Look at leaves of the same plant on the shady side and compare it with the leaves on the sunny side. Or, compare the potted plants kept in the sunlight with those in the shade. Which of them has leaves that are darker green ? Why?


Leaves in the shade get less sunlight to carry out photosynthesis than the plants kept in sunlight. In leaves that get less sunlight, more chlorophyll is present to carry out photosynthesis efficiently. In the presence of strong light, the orientation of the chloroplasts in the mesophyll cells is irregular and in vertical files along the walls. Also, in bright light, photooxidation of chloroplasts takes place while non-oxidation takes place in shaded regions. Hence the plants kept in shade have dark green leaves due to high concentration of chlorophyll.

8. Figure shows the effect of light on the rate of photosynthesis. Based on the graph, answer the following questions:

(a) At which point/s (A, B or C) in the curve is light a limiting factor?

(b) What could be the limiting factor/s in region A?

(c) What do C and D represent on the curve?

NCERT Solutions Class 11-chapter-13-1


a) Light is a limiting factor at A and 50% of B which is due to the increase in the photosynthetic rate with increase in the intensity of light

b) Light, CO2 and H2O could be the limiting factor/s in region A.

c) C indicates 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 photosynthetic rate.

9. Give a comparison between the following:

(a) C3 and C4 pathways

(b) Cyclic and non-cyclic photophosphorylation

(c) Anatomy of leaf in C3 and C4 plants


a) C3 and C4 pathways



RUBP is the primary acceptor of CO2

PEP is the primary acceptor of CO2

3- Phosphoglycerate is the first stable product

Oxalo-acetic acid is the first stable product

Occurs in mesophyll cell of the leaves

Occurs in mesophyll cells and bundle sheath

Process of Carbon fixation is slower

Process of Carbon fixation is faster

b) Cyclic and non-cyclic photophosphorylation

Cyclic photophosphorylation

Non-cyclic photophosphorylation

Occurs only in photosystem-I

Occurs both in Photosystem-I and II

ATP is produced

ATP and NADPH2 are produced

Photolysis of water does not occur hence Oxygen is not produced

Phtolysis of water occurs hence Oxygen is produced

Electrons move in a closed circle

Electrons do not move in a closed circle

c) Anatomy of leaf in C3 and C4 plants

Anatomy of leaf in C3

Anatomy of leaf in C4

Do not possess Kranz anatomy.

They have Kranz anatomy

Chloroplasts are not dimorphic

Chloroplasts are dimorphic, organized centripetally. Size of bundle sheaths are larger

Mesophyll cells possess intercellular space.

Mesophyll cells do not possess intercellular space.

Benefits of NCERT Solutions

NCERT’s Class 11 solution contains extremely important points, and for each chapter, each concept has been simplified to make it easier to remember and increase your chances of achieving excellent exam results. Exam Preparation References Here are some tips on how these solutions can help you prepare for the exam.

  1. This helps students solve many of the problems in each chapter and encourages them to make their concepts more meaningful.
  2. NCERT Solutions for Class 11 solutions encourage you to update your knowledge and refine your concepts so that you can get good results in the exam.
  3. These solutions are the best exam materials, allowing you to learn more about your week and your strengths. To get good results in the exam, it is important to overcome your weaknesses.
  4. Most of the questions in the exam are formulated in a similar way to NCERT textbooks. Therefore, students should review the solutions in each chapter in order to better understand the topic.
  5. It is free of cost.

Tips & Strategies for Class 11 Exam Preparation

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  2. Please refer to the NCERT solution available on the cbsestudyguru website to clarify your concepts every time you prepare for the exam.
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  5. When you read or study a chapter, write down algorithm formulas, theorems, etc., and review them quickly before the exam.
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  7. Take rest and a proper meal.  Don’t stress too much. 

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