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NCERT Solutions for Class 11 Biology Chapter 12 Respiration in Plants
Edited By Irshad Anwar | Updated on May 14, 2025 12:06 PM IST
Plant respiration is how plants break down food they store to make energy for growth and survival. Unlike animals, plants don't have lungs- they breathe through tiny pores called stomata in their leaves and lenticels in their stems. In this chapter, you will learn how plants take in oxygen, release carbon dioxide and create energy using processes like aerobic and anaerobic respiration. The question and answers explain these concepts step-by-step, including how glucose breaks down to form ATP, the energy currency of the cell. The Respiration in Plants solutions will help students understand the full respiration process, making it easier to score better in exams and build a strong foundation for competitive exams like NEET.
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This Story also Contains
- NCERT Solutions For Class 11 Biology Chapter 12 Respiration in Plants PDF Download
- NCERT Solutions for Class 11 Biology Chapter 12 Respiration in Plants Solved Exercise
- Most Important Questions for Class 11 Biology: Respiration in Plants
- Approach to Solve Questions of NCERT Chapter 12 Biology Class 11
- What Extra Should Students Study Beyond the NCERT for NEET?
- Chapter Wise NCERT Solutions for Class 11 Biology
To help students understand these concepts more clearly, Respiration in Plants NCERT Solutions for Class 11 gives step-by-step solutions to textbook problems. With the help of NCERT Solutions, students can learn about these important topics more easily.
NCERT Solutions For Class 11 Biology Chapter 12 Respiration in Plants PDF Download
Here is the PDF of exercise solutions to make learning easier for students:
Also, Read
- NCERT Notes for Class 11 Biology Respiration in Plants
- NCERT Exemplar for Class 11 Biology Respiration in Plants
NCERT Solutions for Class 11 Biology Chapter 12 Respiration in Plants Solved Exercise
The questions with detailed explanations are given below:
(a) Respiration and Combustion
Answer:
Feature | Respiration | Combustion |
Where it Happens | Inside living cells | Not in cells, it's a general process |
What Kind of Process | A biological process | A chemical process |
Energy Release | Slowly, step by step | All at once, very quickly |
Energy Form | Mostly as ATP (cell's energy currency) | No ATP is made |
Needs Help From | Enzymes (special proteins) | Doesn't need enzymes |
(b) Glycolysis and Krebs cycle
Answer:
Feature | Glycolysis | Krebs Cycle |
Where it Happens | In the cell's cytoplasm | Inside the mitochondria |
Pathway Shape | A straight pathway | A circular pathway |
Needs Oxygen? | Happens with or without oxygen | Needs oxygen to work |
What it Does | Breaks down glucose into pyruvate | Breaks down pyruvate into CO2 and water |
Uses/Makes ATP | Uses a little ATP to get started | Doesn't use ATP |
Q1. Differentiate between (c) Aerobic respiration and Fermentation
Answer:
Feature | Aerobic Respiration | Fermentation |
Where it Happens | Inside cells | Can happen inside or outside cells |
Economic Use | Not used to making things in the industry | Used to make things like wine and bread |
How it Works | Uses oxygen to break down stuff | Breaks down nutrients without using oxygen |
Q2. What are respiratory substrates? Name the most common respiratory substrate.
Answer: Respiratory substrates are those organic compounds which, during respiration, are being oxidized for the release of energy within living cells. Examples of common respiratory substrates are carbohydrates, proteins, fats, and organic acids. The most frequent respiratory substrate is carbohydrates.
Q3. Give the schematic representation of glycolysis.
Answer: The schematic representation of glycolysis is as follows:
Q4. What are the main steps in aerobic respiration? Where does it take place?
Answer: The key steps of aerobic respiration are as follows:
Glycolysis- Cytoplasm
Krebs cycle- Matrix of mitochondria
Electron transport system- Inner mitochondrial membrane
Oxidative phosphorylation- Oxysome in the inner mitochondrial membrane.
Q5. Give the schematic representation of an overall view of Krebs' cycle
Answer: Schematic representation of the Krebs cycle
Q7. Distinguish between the following:
(a) Aerobic respiration and Anaerobic respiration
Answer: The difference between aerobic respiration and anaerobic respiration is given below:
Feature | Aerobic Respiration | Anaerobic Respiration |
Gas Exchange | It involves the exchange of gases | The exchange of gases is absent |
Oxygen Use | It uses oxygen to break the respiratory material into simple substances | It does not use oxygen for the breakdown of respiratory substrates. |
Breakdown of Material | The respiratory material is completely broken | The respiratory material is partially broken |
Electron Transport | It involves electron transport | Electron transport is absent |
Q7. Distinguish between the following:
(b) Glycolysis and Fermentation
Answer: The difference between Glycolysis and Fermentation is given below:
Feature | Glycolysis | Fermentation |
Oxygen | It is the first step of respiration, which occurs without the requirement of oxygen and is common to both aerobic and anaerobic modes of respiration | It is anaerobic respiration or respiration which does not require oxygen |
Product | Glycolysis produces pyruvic acid | Fermentation produces different products such as ethanol and lactic acid. |
NADH Production | It produces two molecules of NADH per glucose molecule | It uses NADH produced during glycolysis. |
Q7. Distinguish between the following:
(c) Glycolysis and Citric acid Cycle
Answer: The difference between Glycolysis and Citric acid Cycle is given below:
Feature | Glycolysis | Citric Acid Cycle |
Location | It takes place inside the cytoplasm | It takes place in mitochondria |
Function | It is the first step of respiration in which glucose is broken down to the level of pyruvate. | It is the second step of respiration wherein an active acetyl group is broken down completely |
Q8. What are the assumptions made during the calculation of the net gain of ATP?
Answer: The assumptions used while calculating the net gain of ATP are as follows:
It is supposed that different steps of aerobic respiration like glycolysis, TCA cycle, and ETS follow one after the other in a regular pathway.
The NADH formed during glycolysis is transported into the mitochondria in order to receive oxidative phosphorylation.
The glucose molecule is taken to be the sole substrate and it is assumed that no other molecule goes into the pathway at intermediate stages.
The intermediates formed in respiration are not used for any other purpose.
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Apply NowQ9. Discuss "The respiratory pathway is an amphibolic pathway."
Answer: The respiratory pathway is an amphibolic pathway because it includes both the breakdown (catabolism) and the synthesis (anabolism) of molecules. Carbohydrates, fats, and proteins are broken into their simpler forms such as glucose, fatty acids, glycerol, and amino acids before respiration. Molecules of the respiratory pathway, such as acetyl CoA, are also utilised for the synthesis of fatty acids and proteins.
Q10. Define RQ. What is its value for fats?
Answer: The respiratory quotient (RQ) is defined as the ratio of the volume of CO2 evolved to the volume of O2 consumed during respiration. The value of the respiratory quotient depends on the type of respiratory substrate. The value of RQ for various respiratory substrates is as follows:
Carbohydrates- 1
Fat - 0.7
Organic acids- more than 1
Proteins - less than 1
Q11. What is oxidative phosphorylation?
Answer: Oxidative phosphorylation is the process of generating ATP through the use of energy released from respiration during the oxidation of NADH and FADH2. The process is facilitated by the presence of the enzyme ATP synthase, which is a component of the electron transport system (ETS). In this process, oxidation-reduction reactions build up a proton gradient. There are two components of ATP synthase: F0 and F1. The F0 component is located in the membrane and has a passage for protons, whereas the F1 component is where ADP and inorganic phosphate get converted into ATP. One ATP molecule is produced for every two protons passing through the F0-F1 complex.
Q12. What is the significance of step-wise release of energy in respiration?
Answer: The respiration process occurs stepwise, involving steps such as glycolysis, the TCA cycle, ETS, and oxidative phosphorylation. The synthesis of ATP during respiration is also in every phase. The products obtained in one step of respiration serve as the substrate of the other pathway. Different molecules generated during respiration are also engaged in other biochemical processes. Various respiratory substrates enter and leave the pathway when needed. The ATP also gets used wherever needed, and the rate of reactions of enzymes is also regulated. Hence, step-by-step release of energy increases the efficiency of the system in extracting as well as storing energy.
NCERT Solutions for Class 11: Subject-wise
Most Important Questions for Class 11 Biology: Respiration in Plants
Below are a few solved practice questions:
Q1. What is the end product of oxidative phosphorylation?
Options:
1. NADH
2. Oxygen
3. ADP
4. ATP + H2O
Answer:
This process is mainly used for the oxidation of nutrients by the use of enzymes in order to release energy and molecular oxygen. A metabolic process called oxidative phosphorylation releases chemical energy and oxidises foods to create adenosine triphosphate (ATP) in cells. For the majority of physiological and biochemical functions, including development, mobility, and equilibrium, it serves as the main energy source.
Hence, the correct answer is option (4) ATP + H2O
Check the NCERT Books and NCERT Syllabus here:
Approach to Solve Questions of NCERT Chapter 12 Biology Class 11
Students should begin by understanding the key processes like glycolysis, the Krebs cycle, and the electron transport chain before solving the questions. They should focus on the difference between aerobic and anaerobic respiration and the role of ATP. The flowchart can be used to remember the sequence of reactions and their intermediates. Solving the exemplar questions will give an advanced approach to the chapter. The Respiration in Plants Class 11 Solutions has all the solved exercise questions, with to-the-point answers and necessary information. Regular revision and practice will improve understanding and accuracy.
What Extra Should Students Study Beyond the NCERT for NEET?
Studying concepts beyond the NCERT will definitely help in attaining conceptual clarity and will help answer application-based questions, especially for competitive exams or school exams. Some extra concepts that can be studied are:
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Tricarboxylic Acid Cycle or Krebs Cycle or Citric Acid Cycle | ✅ | ✅ |
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Chapter Wise NCERT Solutions for Class 11 Biology
Below mentioned are the Chapterwise solutions:
Frequently Asked Questions (FAQs)
1. What are the important topics covered in NCERT Solutions for Class 11 Biology Chapter 12?
The important topics covered in NCERT Solutions for Class 11 Biology Chapter 12 include:
Do Plants Breathe?
Glycolysis
Fermentation
Aerobic Respiration
The Respiratory Balance Sheet
Amphibolic Pathway
Respiratory Quotient.
2. How does the mitochondria function as the powerhouse of the cell in plants?
Mitochondria are the powerhouses of the cell because they generate most of the ATP during aerobic respiration through the Krebs cycle and electron transport chain.
3. What are the important topics of respiration in plants ncert?
These are the important topics of ncert respiration in plants:
- Glycolysis
- Fermentation
- Aerobic Respiration
- Tricarboxylic Acid Cycle
- Electron Transport System (ETS) and Oxidative Phosphorylation
- The Respiratory Balance Sheet
- Amphibolic Pathway
- Respiratory Quotient
4. What is oxidative phosphorylation given in chapter 12 biology class 11 ncert solutions?
Oxidative phosphorylation is the synthesis of energy-rich ATP molecules with the help of energy liberated during oxidation of reduced coenzymes ( NADH and FADH2 ) produced in respiration. TH enzyme required for the synthesis is called ATP synthase. It is the fifth complex of ETS. During this process, a number of oxidation-reduction reactions occur and lead to the generation of a proton gradient.
5. How does aerobic and anaerobic respiration differ in plants?
Aerobic respiration in plants occurs in the presence of oxygen, fully oxidizing glucose into CO₂ and H₂O, primarily in mitochondria, with a high energy output. Anaerobic respiration occurs without oxygen, partially breaking down glucose into ethanol and CO₂, mainly in the cytoplasm, with a lower energy output.
6. What is glycolysis, and where does it occur in plant cells?
Glycolysis is the process by which glucose is converted into pyruvate. It occurs in the cytoplasm of plant cells and is a common pathway for both aerobic and anaerobic respiration.
7. Explain the Krebs cycle in respiration with key steps.
The Krebs cycle (or citric acid cycle) occurs in the mitochondrial matrix and involves the breakdown of acetyl-CoA into CO₂, NADH, FADH₂, and ATP. Key steps include:
- Decarboxylation: Acetyl-CoA enters the cycle by combining with oxaloacetate to form citrate.
- Isomerization: Citrate is converted into isocitrate.
- Oxidation: Isocitrate is oxidized to form α-ketoglutarate, producing NADH and CO₂.
- Decarboxylation: α-Ketoglutarate is converted into succinyl-CoA, releasing another CO₂ and producing NADH.
- Oxidation: Succinyl-CoA is converted into succinate, producing FADH₂.
- Oxidation: Succinate is converted into fumarate, producing FADH₂.
- Hydration: Fumarate is hydrated to form malate.
- Oxidation: Malate is oxidized to form oxaloacetate, producing NADH.
8. How is electron transport system (ETS) involved in plant respiration?
The electron transport system (ETS) is crucial in aerobic respiration, occurring in the mitochondrial inner membrane. It uses electrons from NADH and FADH₂ to generate a proton gradient, which drives ATP synthesis through oxidative phosphorylation.
9. What are the end products of fermentation in plants?
The end products of fermentation (anaerobic respiration) in plants are primarily ethanol and carbon dioxide.
10. Why is the respiratory quotient (RQ) important in plant respiration?
The respiratory quotient (RQ) is important because it helps determine the type of substrate being respired and the efficiency of respiration. An RQ of 1 indicates carbohydrate respiration, while values less than 1 suggest fat or protein respiration.
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