NCERT Solutions for Class 11 Biology Chapter 12 - Respiration In Plants

Question 1: Differentiate between 

a) Respiration and Combustion 

b) Glycolysis and Krebs’ cycle 

c) Aerobic respiration and Fermentation 

Ans: 

a) Differences between respiration and combustion are as follows:

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

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

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

Ans: 

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. 

Ans:

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):

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.

Question 7: Distinguish between the following: 

a) Aerobic respiration and Anaerobic respiration. 

b) Glycolysis and Fermentation.

c) Glycolysis and Citric acid cycle.

Ans: 

a) Aerobic respiration and Anaerobic respiration

(b) Glycolysis and Fermentation

3. Glycolysis and Citric acid cycle

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? 

Ans: 

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 12 - Respiration in Plants

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.

Chapter 12 of NCERT Class 11 Biology explains cellular respiration in plants and how it leads to the release of energy through the process of disintegration of food within the cells. The energy released is stored for the synthesis of ATP. 

This chapter will help students in understanding the process of respiration and how it is carried out in living beings. The oxidation of certain macromolecules derived from food provides all the energy required for life processes. Photosynthesis is a process in which light energy is trapped and turned into chemical energy and this process is used by the autotrophs to produce their food. Green plants, various tissues, and non-green cells thus, always require food for oxidation.

The important topics included under NCERT Class 11 Biology Chapter 12 are given in the table below.

Importance of NCERT Class 11 Biology Chapter 12 Topics

NCERT Class 11 Biology Chapter 12 Respiration in Plants comes under Unit 4 ‘Plant Physiology’ and is an important chapter for Class 11 CBSE Term II exam. The topics covered in this chapter such as Glycolysis, Aerobic Respiration, and Amphibolic pathways are very important and students can expect a weightage of about 18 marks in the term II exam on these topics. Topics like oxidative phosphorylation will help students to understand the electron transport system in a precise manner and the steps involved in the conversion of ADP into ATP.

NCERT Solutions for Class 11 Biology Chapter 12 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 12 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 12 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.

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