NCERT Solutions for Class 11 Biology Chapter 14

NCERT Solutions for Class 11 Biology Chapter 14 - Respiration in Plants

CBSE NCERT Solutions of Class 11 Biology Chapter 14 are a very crucial part of anyone’s exam preparation. A student can easily solve the challenges faced while going through the chapter. Class 11 Biology Chapter 14 Respiration in Plants NCERT Solution is uniquely drafted by the subject matter experts at Vedantu which provide readymade answers to the various questions given in the academic textbook of Class 11th Biology. 

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Access NCERT Solutions for Class 11 Biology Chapter 14 – Respiration in Plants part-1

Access NCERT Solutions for Class 11 Biology Chapter 14 – Respiration in Plants

Question 1: Differentiate between 

a) Respiration and Combustion 

b) Glycolysis and Krebs’ cycle 

c) Aerobic respiration and Fermentation 


a) Differences between respiration and combustion are as follows:



It occurs inside living cells (cellular process).

It is a non-cellular process

Respiration is a biochemical process.

Combustion is a physio-chemical process.

Chemical bonds are broken down into steps, as a result, energy is released in stages.

All chemical steps occur simultaneously, as a result, energy is released in a single step.

A considerable amount of energy is stored in ATP molecules.

ATP is not formed.

Oxidation occurs at the end of the reaction (terminal oxidation) between reduced coenzymes and oxygen.

During combustion, the substrate is oxidized directly.

Several intermediates are formed. They are utilized in the synthesis of various organic compounds

No intermediates are produced in combustion.

Less than 50% of energy is liberated in the form of heat energy. Light is rarely produced.

Energy is liberated in the form of both light and heat energy.

Temperature is not allowed to rise.

Temperature becomes very high.

Several enzymes are needed, one for each step or reaction.

Burning is a non-enzymatic process.

b) Differences between glycolysis and Krebs’ cycle are as follows:


Krebs’ Cycle

It occurs inside the cytoplasm.

Krebs’ cycle operates inside mitochondria.

Glycolysis is the first step in respiration where glucose is broken down to pyruvate.

Krebs' cycle is the second step in respiration in which an active acetyl group is broken down completely.

This process is common in both aerobic and anaerobic respiration.

It only occurs during aerobic respiration.

It degrades a molecule of glucose into 2 molecules of pyruvate, an organic substance.

It degrades pyruvate completely into inorganic substances i.e., \[{\text{C}}{{\text{O}}_{\text{2}}}\] and ${{\text{H}}_{\text{2}}}{\text{O}}$.

Glycolysis requires two ATP molecules for the initial phosphorylation of the substrate molecule.

It does not require ATP molecules.

One glucose molecule yields four ATP molecules in glycolysis through substrate-level phosphorylation.

Two acetyl residues in the Krebs cycle liberate two ATP or GTP molecules through substrate-level phosphorylation.

The net gain is 2 molecules of NADH and 2 molecules of ATP for every molecule of glucose broken down.

Krebs’ cycle produces 6 molecules of NADH, and 2 molecules of ${\text{FAD}}{{\text{H}}_{\text{2}}}$ for every two molecules of ${\text{acetyl}}\;{\text{CoA}}$oxidized by it. Two molecules of NADH are released during the conversion of two pyruvates to ${\text{acetyl}}\;{\text{CoA}}$.

The net gain of energy during glycolysis is equal to 8 ATP molecules.

In krebs' cycle, the net gain of energy is equal to 24 ATP molecules. Six molecules of ATP can be produced from 2 molecules of ${\text{NAD}}{{\text{H}}_{\text{2}}}$ formed during the dehydrogenation of 2 pyruvates.

In glycolysis, no \[{\text{C}}{{\text{O}}_{\text{2}}}\] is evolved.

\[{\text{C}}{{\text{O}}_{\text{2}}}\] is evolved during Krebs’ cycle.

Oxygen is not required for glycolysis.

Oxygen is used as a terminal oxidant during krebs' cycle.

c) Differences between aerobic respiration and fermentation are as follows:

Aerobic Respiration


It uses oxygen for breaking the respiratory material into simpler substances.

Oxygen is not used in the breakdown of the respiratory substrate.

Respiratory material is completely oxidized.

Respiratory material is incompletely broken.

The end products are inorganic i.e., \[{\text{C}}{{\text{O}}_{\text{2}}}\]and ${{\text{H}}_{\text{2}}}{\text{O}}$.

Small, reduced organic molecules (ethanol or lactic acid) are produced as end products. Inorganic substances (\[{\text{C}}{{\text{O}}_{\text{2}}}\]) may or may not be produced.

Aerobic respiration is known for the normal mode of respiration in both plants and animals.

It occurs in yeast cells, bacteria and in the muscle cells of animals during vigorous exercise.

Aerobic respiration consists of three-step: - Glycolysis, Krebs’ cycle and terminal oxidation.

Anaerobic respiration or fermentation consists of two steps: - Glycolysis and incomplete breakdown of pyruvic acid.

Every carbon atom in the food is oxidised, releasing a substantial amount of carbon dioxide.

Less quantity of carbon dioxide is evolved.

Water is formed.

Water is usually not formed.

$686\;{\text{kcal}}$ of energy is produced per gm mole of glucose.

$39 - 59\;{\text{kcal}}$ of energy is produced per gm mole of glucose.

It continues indefinitely.

It cannot be continued indefinitely (except in some microorganisms) due to the accumulation of poisonous compounds and the reduced availability of energy per gram mole of food broken.

Question 2: What are respiratory substrates? Name the most common respiratory substrate. 


Respiratory substrates are organic substances. They are oxidized during respiration to release energy within living cells. Carbohydrates, proteins, fats, and organic acids are common respiratory substrates. The most common respiratory substrates are glucose (carbohydrates). It is a type of hexose monosaccharide.

Question 3: Give the schematic representation of glycolysis. 


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Question 4: What are the main steps in aerobic respiration? Where does it take place?

Ans: The main steps of aerobic respiration are as follows: - Glycolysis, link reaction, Krebs cycle and terminal oxidation.

  1. Glycolysis (EMP Pathway):- The process of breakdown of glucose into pyruvic acid is known as glycolysis. Glucose is partially oxidized to form two molecules of pyruvate, two NADH, and two ATP. This is a common pathway for both aerobic and anaerobic modes of respiration. It takes place in the cytoplasm.

  2. Link Reaction (Gateway Reaction):- Pyruvic acid undergoes oxidative decarboxylation to form ${\text{acetyl}}\;{\text{CoA}}$ and NADH. This reaction occurs within the matrix of mitochondria.

  3. Krebs' Cycle (TCA Cycle):- The Krebs’ Cycle occurs within the matrix of mitochondria.  The net gain of energy is equal to 24 ATP molecules along with other products.

  4. Terminal Oxidation:- Electron Transport System or oxidative phosphorylation takes place in the inner mitochondrial membrane.

Question 5: Give the schematic representation of an overall view of Krebs’ cycle. 

Ans: The schematic representation of an overall view of krebs’ cycle (Citric acid cycle):

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Question 6: Explain ETS.

Ans: The electron transport system (ETS) is also called Oxidative Phosphorylation. It is present in the inner mitochondrial membrane. It's a metabolic pathway that allows electrons to go from one carrier to the next. The passes of electrons from NADH and ${\text{FAD}}{{\text{H}}_{\text{2}}}$ to oxygen (${{\text{O}}_{\text{2}}}$) is facilitated by five multiprotein complexes in the ETS. The complexes are: - Complex I (NADH dehydrogenase), Complex II (Succinate dehydrogenase), Complex III (\[{\text{Cytochrome b}}{{\text{c}}_{\text{1}}}{\text{ Complex}}\]), Complex IV (Cytochrome c oxidase) and Cytochrome V (ATP Synthase). The steps involved in ETS are as follows: -

  1. Electrons from NADH produced in the inner mitochondrial matrix during the citric acid cycle are oxidized by NADH dehydrogenase (Complex I).

  2. Post this, electrons are transferred to Ubiquinone which receives reducing equivalents via ${\text{FAD}}{{\text{H}}_{\text{2}}}$ (Complex II). 

  3. Ubiquinol (reduced ubiquinone) is then oxidized with the transfer of electrons to Cytochrome c via \[{\text{Cytochrome b}}{{\text{c}}_{\text{1}}}{\text{ Complex}}\] (Complex III). 

  4. Cytochrome c oxidase Complex (Complex IV) contains cytochromes a, ${a_3}$ and two ${\text{Cu}}$ centres.

  5. When electrons travel from one carrier to another in the electron transport chain via complex I to IV, they are connected to ATP Synthase (complex V).

  6.  Complex V consists of components like ${F_1}$ (peripheral membrane protein complex) and ${F_0}$ (integral membrane protein complex). At ${F_1}$ATP is synthesized from ADP and Pi. Protons passing through channels formed by ${F_0}$ are coupled to the catalytic site of ${F_1}$.

  7. One molecule of NADH (oxidized) provides 3 molecules of ATP. One molecule of ${\text{FAD}}{{\text{H}}_{\text{2}}}$ produces 2 molecules of ATP.

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Question 7: Distinguish between the following: 

a) Aerobic respiration and Anaerobic respiration. 

b) Glycolysis and Fermentation.

c) Glycolysis and Citric acid cycle.


a) Aerobic respiration and Anaerobic respiration

Aerobic Respiration

Anaerobic respiration

It occurs in the presence of oxygen.

It occurs in the absence of oxygen.

It is a type of respiration in which food (generally carbohydrates) is completely oxidized to carbon dioxide and water with the release of chemical energy.

It is a type of respiration in which food (generally carbohydrates) is partially oxidized with the release of chemical energy.

Since the substrate is completely oxidized, the energy yield of this type of respiration is more than that of anaerobic respiration.

Since the substrate is oxidized partially, the energy yield of this type of respiration is lower than that of aerobic respiration.

Complete oxidation of one molecule of glucose leads to a net gain of 38 ATP molecules.

Partial oxidation of one molecule of glucose leads to a net gain of 2 ATP molecules.

The end product of aerobic respiration is ${\text{C}}{{\text{O}}_{\text{2}}}$ and ${{\text{H}}_{\text{2}}}{\text{O}}$ (all higher organisms).

The end product of anaerobic respiration is lactic acid (animal cells), ethanol and ${\text{C}}{{\text{O}}_{\text{2}}}$ (lower organisms like bacteria and yeast).

Some reactions of aerobic respiration occur in the cytoplasm (glycolysis) and the mitochondria (Krebs’ cycle and ETS).

All reactions of anaerobic respiration occur in the cytoplasm. There is no involvement of mitochondria in this process.

${{\text{C}}_6}{{\text{H}}_{12}}{{\text{O}}_6} + 6{{\text{O}}_2} \to 6{\text{C}}{{\text{O}}_2} + 6{{\text{H}}_2}{\text{O}} + 686{\text{Kcal}}$

${{\text{C}}_6}{{\text{H}}_{12}}{{\text{O}}_6} \to 2{\text{C}}{{\text{O}}_2} + 2{{\text{C}}_2}{{\text{H}}_5}{\text{OH}} + 59{\text{Kcal}}$

(b) Glycolysis and Fermentation



Glycolysis is a common pathway for both aerobic and anaerobic modes of respiration.

Fermentation is a type of anaerobic respiration which occurs in the absence of oxygen.

Glucose is split into two molecules of pyruvic acid during glycolysis.

During fermentation, pyruvic acid is converted to ethyl alcohol (yeast and some other microbes) or lactic acid (muscle cells of humans).

Glycolysis results in a net gain of 2 molecules of ATP.

No ATP is produced during fermentation.

It gives out two molecules of NADH per glucose molecule.

It generally utilizes NADH produced during glycolysis.

  1. Glycolysis and Citric acid cycle


Citric Acid Cycle

Glycolysis is the first step of respiration.

The citric acid cycle (Krebs’ cycle or TCA Cycle) is the second step of respiration.

This process happens in the cytoplasm.

This process occurs in the matrix of mitochondria.

It occurs both aerobically and anaerobically.

It occurs anaerobically.

Two ATPs are consumed during this process.

No consumption of ATP in the citric acid cycle.

The total gain of ATP is 8 (which includes NADH).

The net gain of ATP is 24.

Oxidative phosphorylation is not involved.

Oxidative phosphorylation is involved.

It is a linear pathway.

It is a circular pathway.

Carbon-di-oxide has not evolved.

Carbon-di-oxide is evolved.

Question 8: What are the assumptions made during the calculation of net gain of ATP?

Ans: Calculating the net gain of ATP for each glucose molecule oxidised is doable, but it could only be a theoretical exercise in practise. These calculations can only be made based on the following assumptions:

  1. There is a sequential, orderly pathway is in function, with one substrate forming the next and glycolysis, TCA cycle, and ETS pathway occurring one after the other.

  2. The NADH produced during glycolysis is transferred to the mitochondria and undergoes oxidative phosphorylation. None of the intermediates in the pathway is used to make another compound.

  3. Only glucose is respired. No other alternative substrates enter the pathway at any of the intermediate stages.

These kinds of assumptions, however, are not valid in a living system. All pathways occur simultaneously and do not occur one after the other. Substrates enter the pathways and are withdrawn from them as needed. ATP is used as and when it is required. Multiple factors influence enzymatic rates. As a result, aerobic respiration of one molecule of glucose can result in a net gain of 36 ATP molecules.

Question 9: Discuss “The respiratory pathway is an amphibolic pathway”. 

Ans: The amphibolic pathway is the one that is used for both breakdown (catabolism) and build-up (anabolism) reactions. Respiratory pathways are mainly a catabolic process that serves to run the living system by providing energy. Several intermediates are produced by the respiratory pathway. Many of them serve as raw materials for the formation of both primary and secondary metabolites. ${\text{acetyl}}\;{\text{CoA}}$ is essential not only for the Krebs cycle but also for the synthesis of fatty acids, aromatic compounds, steroids, terpenes and carotenoids. In amination, $\alpha  - $ketoglutarate forms glutamate (an important amino acid). In amination, OAA (Oxaloacetic acid) produces aspartate. Aspartate and glutamate are components of proteins. Other products include pyrimidines and alkaloids. Succinyl CoA is the precursor to cytochromes and chlorophyll.

When fatty acids are used as a substrate, they are broken down to ${\text{acetyl}}\;{\text{CoA}}$ before entering the respiratory pathway. ${\text{acetyl}}\;{\text{CoA}}$ is withdrawn from the respiratory pathway when the organism needs to synthesize fatty acids.

As a result, the respiratory pathway is involved in both the breakdown and synthesis of fatty acids.

Similarly, respiratory intermediates serve as a link during the breakdown and synthesis of proteins. Catabolism is the breaking down processes within a living organism, while anabolism is the synthesis of new ones. Since the respiratory system is engaged in both anabolism and catabolism in plants, it is better to think of it as an amphibolic instead of a catabolic pathway.

Question 10: Define RQ. What is its value for fats? 


The ratio of the volume of ${\text{C}}{{\text{O}}_{\text{2}}}$ evolved to the volume of ${{\text{O}}_{\text{2}}}$ consumed in respiration over a given period is known as a respiratory quotient (RQ) or respiratory ratio. Its value can be equal to one, zero, more than one or less than one. 

${\text{RQ}} = \dfrac{{{\text{ Volume of C}}{{\text{O}}_2}{\text{ evolved }}}}{{{\text{ Volume of }}{{\text{O}}_2}{\text{ consumed }}}}$

When fat or protein is used as a respiratory substrate, the respiratory quotient (RQ) is less than one.

${{\text{C}}_{57}}{{\text{H}}_{104}}{{\text{O}}_6} + 80{{\text{O}}_2} \to 57{\text{C}}{{\text{O}}_2} + 52{{\text{H}}_2}{\text{O}}$

${\text{RQ}} = \dfrac{{57{\text{C}}{{\text{O}}_2}}}{{80{{\text{O}}_2}}}$

$\quad  = 0.71$

The respiratory quotient (RQ) is about 0.7 for most of the common fats.

Question 11: What is oxidative phosphorylation?

Ans: The process by which ATP is formed as a result of the transfer of electrons from NADH or ${\text{FAD}}{{\text{H}}_{\text{2}}}$ to ${{\text{O}}_{\text{2}}}$ by a series of electron carriers is known as oxidative phosphorylation. This process, which occurs in mitochondria, is the primary source of APT in aerobic organisms.

For example, when glucose is completely oxidized to ${\text{C}}{{\text{O}}_{\text{2}}}$ and ${{\text{H}}_{\text{2}}}{\text{O}}$, oxidative phosphorylation generates 26 of the 30 molecules of ATP.

Question 12: What is the significance of the stepwise release of energy in respiration? 

Ans: The following are the benefits of stepwise release of energy in respiration: -

  1. There is a gradual release of chemical bond energy, which is easily trapped in the formation of ATP molecules.

  2. The temperature of the cell is not allowed to rise.

  3. Energy waste is reduced.

  4. A variety of intermediates can be used in the production of a variety of biochemicals.

  5. Different substances can undergo respiratory catabolism via their metabolic intermediates.

  6. Each step of respiration is regulated by its enzyme. Specific compounds can either increase or decrease the activity of various enzymes. This aids in controlling the rate of respiration as well as the amount of energy released.

NCERT Solutions for Class 11 Biology Chapter 14 - Respiration in Plants

Respiration in Plants Class 11 NCERT Solutions PDF

These solutions for Respiration in Plants Class 11 NCERT Biology for Class 11 recommended by CBSE provided by Vedantu in NCERT Biology Class 11 respiration PDF format helps in easy referring of the various questions in the textbook which in turn helps a student in active learning and understanding of the concepts which automatically results in securing higher marks. These solutions are very helpful in the basic understanding of the subject and the answer format which would help any student scoring better in academics. 

One of the best ways to learn and understand Respiration in Plants Class 11th NCERT is by referring to the NCERT solutions. In these solutions, the difficult and twisted terms are explained in the simplest way. The confusing and complicated parts are broken into fragments and explained to make understanding easier and helpful. The best thing about these NCERT solutions is that they have been put together by experienced Biologists turned professors.

NCERT Solutions for Class 11 Biology Chapter 14 Respiration in Plants

We all breathe to live, yet why is breathing so fundamental to life? What happens when we relax? Likewise, do every single living life form, including plants and microorganisms, relax? Assuming this is the case, how? All living life forms require energy for completing everyday life exercises, be it ingestion, transport, development, multiplication, or in any event, relaxing. 

Where does this energy originate from? We realize we eat nourishment for energy – however, how is this energy taken from food? How is this energy used? Do all food give a similar measure of energy? Do plants 'eat'? Where do plants get their energy from? Also, miniature life forms – for their energy necessities, do they eat 'food'? You may marvel at the few inquiries raised above – they may appear to be detached. In any case, truly, the way toward breathing is a lot associated with the cycle of the arrival of energy from food.

All the energy needed forever measures is gotten by oxidation of certain macromolecules that we call 'food'. Just green plants and cyanobacteria can set up their own food; by the cycle of photosynthesis, they trap light energy and convert it into compound energy that is put away in the obligations of sugars like glucose, sucrose, and starch. We should recollect that in green plants as well, not all cells, tissues, and organs photosynthesize; just cells containing chloroplasts, that are regularly situated in the shallow layers, do photosynthesis.

Division of Marks for Respiration in Plants Class 11 NCERT

This chapter falls under unit 4 which has a weightage of 18 marks. One can expect either a basic 1 mark question or an elaborate 5 mark question.

Advantages of NCERT Solutions for Class 11 Biology Chapter Respiration in Plants

The Class 11 Bio Ch 14 NCERT solutions help students acquaint themselves to understand and develop the ability to answer questions in a certain format which are compatible to the CBSE guidelines. Students can use these NCERT Solutions for their revision and doubt clearing purpose as well. They can also refer to these to rectify their mistakes once they complete solving all the exercises’ questions. 

These resources are of outstanding quality which can be trusted blindly. Vedantu experts cover all the questions mentioned in the Ch 14 Biology Class 11 NCERT solutions Biology. Solving questions from Biology textbook and referring to the NCERT Solutions for Class 11 Biology chapter Respirations in Plants for better assistance will always help the students comprehend the concepts effectively.

FAQs (Frequently Asked Questions)

Q1. What are the core stages of aerobic respiration? Where does it take place?

Ans: Aerobic respiration is an enzymatically meticulous arrival of energy in a stepwise catabolic cycle of whole oxidation of natural food into carbon dioxide and water with oxygen going about as terminal oxidant. It happens by two techniques, normal pathway, and pentose phosphate pathway. The regular pathway is known so in light of the fact that its initial step, called glycolysis, is basic to both high-impact and anaerobic methods of breath. The normal pathway of oxygen-consuming breath comprises three stages – glycolysis, Krebs' cycle, and terminal oxidation. Vigorous breath happens inside mitochondria. The eventual outcome of glycolysis, pyruvate is shipped from the cytoplasm into the mitochondria.

Q2. What kind of assumption is made during the calculation of the net gain of ATP?

Ans: To calculate the net addition of ATP for each glucose particle oxidized possible; however, actually, this can stay just a hypothetical exercise. These estimations can be made distinctly on specific suspicions that:

  • There is a consecutive, methodical pathway working, with one substrate shaping the following and with glycolysis, TCA cycle and ETS pathway following in a steady progression moved into the mitochondria and goes through oxidative phosphorylation.

  • Only glucose is being breathed – no other elective substrates are entering in the pathway at any of the go-between stages.

Yet, these sorts of suppositions are not generally substantial in a living framework; all pathways work all the while and don't occur consistently; substrates enter the pathways and are pulled back from it as and when important; ATP is used as and when required; enzymatic rates are constrained by various methods. Consequently, there can be a net increase of 36 ATP particles during an oxygen-consuming breath of one atom of glucose.

Q4. What concepts can I learn from the NCERT Solutions for Class 11 Biology Chapter 14?

Ans: Chapter 14 is about Respiration in Plants. The concepts that you can learn from the NCERT Solutions for Class 11 Biology Chapter 14 are “Do Plants Breathe?”, Glycolysis, Fermentation, Aerobic Respiration, The Respiratory Balance Sheet, Amphibolic Pathway and Respiratory Quotient. These topics are made very easy for the students in NCERT Solutions. The concepts are very easy to understand and given in an organised manner.

Q4. Are the NCERT Solutions for Class 11 Biology Chapter 14 sufficient for exam preparation?

Ans: Yes, if your preparation from the NCERT Solutions for Class 11 Biology Chapter 14  is thoroughly done with the practice of all the questions and answers from the exercises and the important questions, you are all prepared for the exam. You can also practise the sample question papers to get an idea of writing the answers appropriately. Go through the NCERT Solutions from start to end, and you will be confident with your subject. The solutions are accessible free of cost on the Vedantu website as well as the Vedantu Mobile app.

Q5. What is respiration in plants Class 11?

Ans: Respiration in plants is the release of energy through the enzymes, which is a catabolic process, which involves the breakdown of the food substances inside the living cells. The energy is required by all living organisms for all the activities like breathing, absorption, reproduction and movement. The important aspect of respiration is the liberation of metabolic energy as ATP.

Q6. What is Aerobic Respiration NCERT Solutions?

Ans: Aerobic respiration involves the exchange of gases in the presence of oxygen. This will give rise to the breakdown of respiratory materials giving carbon dioxide and water as end products. The process of glycolysis is involved in aerobic respiration. The acid produced during aerobic respiration is pyruvic acid, and it forms two ATP for each glucose molecule.

Q7. What is the respiratory balance sheet Class 11?

Ans: The respiratory balance sheet in Class 11 Biology Chapter 14 is the calculation of net gain of ATP for every glucose molecule oxidised, which depends on the orderly pathway functioning with the next substrate and with glycolysis, TCA cycle, NADH synthesised in glycolysis which is transferred to mitochondria and undergoes the process of oxidative phosphorylation, the respired compound is only glucose, and none of the intermediates in the pathway is utilised for synthesising any other compound.

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