RBSE Class 12 Biology Chapter 11- Respiration. In this chapter, students can learn in detail about the types of respiration, respiratory substrates, site of respiration, the difference between aerobic and anaerobic respiration, mechanism of aerobic and anaerobic respiration. It also deals with the summary of glycolysis, krebs cycle, TCA cycle, Citric acid cycle, respiratory quotient, fermentation and its types and a lot more.
These important questions help students to perform exceptionally well in their exams. By practising these important questions, students can analyze their preparation, get a thorough knowledge about all the important terminologies, and at the same time, it builds students confidence towards the exam and their preparations.
RBSE Solutions for Class 12 are the best study material for both class assignments and other board examinations. By practising these important questions, students can gain deep knowledge about the topics explained in this chapter and also help them to be well prepared for their upcoming examinations.
RBSE Class 12 Biology Chapter 11 Important Questions
RBSE Biology Chapter 11: MCQ Type Questions
Q.1. How many ATP molecules are formed when 2 NADH + H+ formed in glycolysis enter ETS via malate aspartate shuttle?
(a) Two.
(b) Four.
(c) Eight.
(d) Six
Sol:(d). Six
Q.2. The net gain of energy in glycolysis is_________.
(a) Twelve ATP.
(b) Two ATP.
(c) Four ATP.
(d) Zero ATP.
Sol:(b) Two ATP.
Q.3. What is the site of Krebs cycle in cells?
(a) Nucleus.
(b).Cytoplasm.
(c) Plastids.
(d) Mitochondria
Sol:(d) Mitochondria
Q.4. How many ATP molecules are formed as a net gain in anaerobic respiration?
(a) Two.
(b) Three.
(c) Four.
(d) Eight.
Sol:(a) Two.
Q.5. Which of the following molecules is called the universal energy coin of the cell?
(a) ATP.
(b) AMP.
(c) DNA.
(d) RNA.
Sol: (a) ATP.
Q.6. The conversion of pyruvic acid into acetyl CoA occurs in_________.
(a) Cytoplasm.
(b) In a matrix of mitochondria.
(c) On cristae. dria.
(d) On the outer membrane of mitochondria.
Sol:(b) In a matrix of mitochondria.
Q.7. Which of the following substrates has the R.Q value less than one?
(a) Fats.
(b) Proteins.
(c) Sugar.
(d) All of the above.
Sol: (b) Proteins.
Q.8. Who proposed the chemiosmotic theory of oxidative phosphorylation?
(a) Krebs.
(b) Gibbs.
(c) Mitchell.
(d) Dixons.
Sol:(c) Mitchell.
Q.9. Which of the following acts as a respiratory substrate during protoplasmic respiration?
(a) Glucose.
(b) Sucrose.
(c) Starch.
(d) Proteins.
Sol: (d) Proteins.
Q.10. The value of Q10 of respiration is _____.
(a) Three.
(b) Two.
(c) Four.
(d) Six.
Sol:(b) Two.
RBSE Biology Chapter 11:Short Answer Type Questions.
Q.1. What is the respiratory quotient? Which instrument is used for measuring respiratory quotient (RQ)?
Sol. Respiratory Quotient (RQ) is defined as the ratio of carbon dioxide and the oxygen used during the process of respiration.
Respiratory Quotient is measured by Ganong’s respirometer.
Q.2.What is the mechanism of aerobic respiration?
Sol. The different stages of aerobic respiration are:
- Glycolysis.
- Electron Transport Chain.
- Kreb’s cycle, Citric acid cycle, TCA cycle.
Q.3. What is aerobic respiration?
Sol. Aerobic respiration is the process involved in the production of energy in the presence of oxygen. In this process of respiration, food glucose is converted into energy in the presence of oxygen.
The below-given chemical equation describes the complete process of photosynthesis or the aerobic respiration in plants.
6(CO2) + 6 (H2O) → (C6H12O6) + 6(O2)
Q.4. What is cellular respiration?
Sol. Cellular respiration is a set of metabolic reactions that take place in all living cells to release energy by converting biochemical energy from nutrients into adenosine triphosphate- ATP. Based on the oxygen demand, cellular respiration is divided into- Aerobic respiration and Anaerobic respiration.
Q.5. What is the respiratory organ in woody stems?
Sol. The respiratory organ consists of all the organs involved in the respiration process. In hard and woody stems, respiration or the exchange of gases takes place through lenticels. They are the small pores, scattered all over the bark and are found in all trees.
Q.6. Do plants breathe at night? How do plants breathe?
Sol. Yes, plants breathe throughout their life span both during the day and night. All green plants breathe through the process of Cellular respiration. In this process, nutrients obtained from the soil are converted into energy and are used for different cellular activities.
Q.7. What is fermentation?
Sol. Fermentation is a chain of chemical reactions or a metabolic process through which all living organisms obtain the energy required for the biological processes. It is an Anaerobic Pathway, which is used for producing alcoholic beverages, Yogurt and other food products.
Q.8. Where does cellular respiration occur in plant cells?
Sol. In all green plants, cellular respiration takes place in the mitochondria of the cell during the presence of oxygen. During the process of cellular respiration roots, stems, and leaves of plants exchange gases for respiration separately.
Q.9. What is anaerobic respiration?
Sol. The respiration process which takes place in the absence of oxygen gas. In this process, the energy is obtained by the breakdown of glucose in the absence of oxygen. One of the best examples of anaerobic respiration is the process of fermentation in yeast.
Q.10. What are the factors affecting the rate of respiration?
Sol. Rate of respiration is affected by many factors. The rate of respiration is high in the meristematic cells. The factors affecting the rate of respiration includes both internal and external factors.
The external factors are — Light, water, oxygen, temperature and carbon dioxide.
The internal factors are — Protoplasm, respiratory factor, age of the cell and injury and wound.
Q.11.How the value of respiratory quotient (RQ) is affected by the nature of respiratory substrates?
Sol. The value of the respiratory quotient (RQ) depends upon the nature of the respiratory substrates. The value of respiratory quotient (RQ) is variable according to the substrate. The substrate having more oxygen in comparison to carbon requires less amount of oxygen for oxidation and their respiratory quotient is less than one.
R.Q. of carbohydrates – 1.0
R.Q. of fats = 0.7 (< 1)
R.Q. of proteins = 0.8 (< 1)
R.Q. of organic acids = 1.33 (> 1)
Q.12.What is the respiration quotient of carboxylic acids?
Sol. In a few plants, respiratory substrates are carboxylic acid, which has more oxygen compared to carbon in its molecule. That is why, for the oxidation of these substances, the need for external oxygen is very less and carbon dioxide is released in high amounts. Therefore, the respiratory quotient is always more than one.
Oxalic acid 2(COOH) + O2 → 4CO2 + H2O
Respiratory quotients =
The Respiratory quotients of citric acid and malic acid are 1.14 and 1.33, respectively.
Q.13. Why do fruits and vegetables remain fresh for a longer duration in cold storage?
Sol. Fruits and vegetables have a long life when they are stored in cold storage. This is because, at low temperature, the rate of respiration is very low and the microbial activity is extremely low. Therefore, the fruits and vegetables escape spoilage and remain fresh and safe for a longer duration.
Q.14.What is the difference between free-floating respiration and protoplasmic respiration?
Sol. In free-floating respiration, carbohydrates are used as a respiratory substrate, whereas in protoplasmic respiration, proteins are used as a respiratory substrate. Free-floating respiration is a normal respiration process of an organism and the protoplasmic respiration takes place when all carbohydrates and fats are utilized by the body when the organism is under starvation condition.
Q.15. What is the respiratory substrate?
Sol. Complex compounds or high energy compounds oxidized in the process of respiration are called the respiratory substrate. These substrates are stored in a cell in the form of carbohydrates, fats and proteins molecules. Glucose is the first respiratory substrate of respiration.
Q.16. What are the sites of respiration?
Sol. Main sites for respiration in all eukaryotic organisms is mitochondria. It is a double membrane cell organelle which is bounded with the external and internal membrane. These membranes are made up of lipoprotein.
Q.17. What is the use of respiratory quotient (RQ)?
Sol. Respiratory quotient (RQ) is a very helpful method used to determine the substrate used in respiration and type of respiration. Different substrates used in the respiration have different respiratory quotients.
Q.18. Write a note on Pentose Phosphate Path (PPP).
Sol. Pentose Phosphate Path (PPP) is an alternative path for complete oxidation of glucose. In this process, hexose sugar is oxidized through the involvement of five carbon-containing sugar. This is called the Pentose Phosphate Path. Racker and co-workers were the first to study the reaction of PPP in 1954.
Q.19. Draw an outline diagram showing the interrelationship between respiratory substrates.
Sol.
Q.20. Who gave the theory of chemiosmotic theory of oxidative phosphorylation?
Sol. Advanced principle of oxidative phosphorylation is also known as the chemiosmotic theory of oxidative phosphorylation. This theory was given by Peter Mitchel, for which he received the Nobel prize. According to this theory, the transport of protons from matrix to intermembrane space is accompanied by the generation of a proton gradient across the membrane.
RBSE Biology Class 12: Long Answer Type Questions
Q.1. Write the difference between Aerobic respiration and Anaerobic respiration.
Sol. The primary difference between aerobic and anaerobic respiration is the presence or absence of oxygen during the processes. More detailed differences are between the two are as follows:
| Aerobic Respiration | Anaerobic Respiration |
| Takes place in the presence of oxygen. | Takes place in the absence of oxygen. |
| Gases are exchanged. | There is no exchange of gases. |
| It is found in the cytoplasm and the mitochondria. | It is found only in the cytoplasm. |
| Glucose breaks down into carbon dioxide and water. | Glucose breaks down into ethyl alcohol, carbon dioxide and energy |
| A high amount of energy is produced. | Less amount of energy produced. |
| Total number of ATP released is 38 ATP | Total number of ATP released is 2 ATP |
| Final product is carbon dioxide and water. | The final product is carbon dioxide and ethanol. |
| C₆H₁₂O₆ + O2 –CO2 + H2O + ATP | C₆H₁₂O₆ — C3H6O3 + ATP |
| It involves glycolysis, a citric acid cycle. | It involves glycolysis followed by fermentation. |
| Aerobic respiration is carried out in all higher organisms including humans, animals, and plants. | Anaerobic respiration is carried out in all lower organisms such as bacteria, yeast, E. coli, etc. |
Q.2. What is respiration? List out the importance of respiration.
Sol. Respiration is a metabolic process that occurs in all organisms. It is considered a biochemical process that occurs within the cells of organisms. In this process, the energy (ATP-Adenosine triphosphate) is produced by the breakdown of glucose which is further used by cells in various functions.
Respiration is the most vital process of all living organisms. It occurs in all very living species, from a single-celled organism to dominant multicellular organisms.
Other importance of respiration are:
- This process converts potential energy into kinetic energy.
- The energy released during the respiration process is utilized by the living cell for various anabolic reactions.
- As a result of this reaction, many intermediate chemical substances are formed which are necessary for the metabolism of a cell.
- Carbon dioxide released in this reaction maintains the gaseous balance of the environment.
- In this reaction, the complex insoluble food substances are converted into soluble food substances.
Q.3. What is the respiratory quotient(RQ) of protein and fats?
Sol. The respiratory quotient of fats.
Fat is the respiratory substrate during the germination of oily seeds like mustards, groundnuts, cotton, millets, etc. The molecules of fat have less oxygen in comparison to carbohydrates. Therefore, for the oxidation of fats more of the environmental oxygen is required. Therefore, the respiratory quotient of fat is always less than one.
Tripalmitin C51H98O6 + 145 O2 → 102CO2 + 98H2 O
Respiratory quotient of fat = 120/145 = 0.7
Respiratory quotients =
The respiratory quotient of Proteins
Protein molecules also have less amount of oxygen in comparison to carbon like fats. In the respiration process, proteins work as respiratory substrates only in the absence of carbohydrates and fats. If humans keep fasting for a longer time without food, these proteins are used as a respiratory substrate, which is an indication of death in humans. if it continues.
The respiratory quotient of Protein is less than one, mostly 0.7 to 0.9, which is little more than the respiratory quotient of fats.
Q.4. Define Kreb’s Cycle. List out the importance of Kreb’s Cycle.
Sol. The Krebs cycle is also called the citric acid cycle. It is an aerobic process that takes place in the mitochondrial matrix and involves the oxidation of pyruvic acid into water and carbon dioxide. It is a series of enzyme catalysed reactions occurring within the mitochondrial matrix, where acetyl-CoA is oxidised to form carbon dioxide and coenzymes are reduced, which generate ATP in the electron transport chain. It is a series of eight-step processes, where the acetyl group of acetyl-CoA is oxidised to form two molecules of CO2 and in the process, one ATP is produced. Reduced high energy compounds, NADH and FADH2 are also produced.
Krebs cycle was named after Hans Krebs, who postulated the detailed cycle. He was awarded the Nobel prize in 1953 for his contribution.
The importance of Kreb’s Cycle:
- In the Krebs cycle, the ATP molecules are formed and they provide energy to do different functions. Therefore, it is the major source of ATP production in the cells.
- It plays an important role in gluconeogenesis and lipogenesis and interconversion of amino acids
- Krebs cycle or Citric acid cycle is the final pathway of oxidation of glucose, fats and amino acids.
- Regulation of Krebs cycle depends on the supply of NAD+ and utilization of ATP in physical and chemical work.
- In the Krebs cycle, many intermediate compounds are formed which are used in other biomolecular syntheses. For example, Succinyl enzyme-A is the initial molecule for the synthesis of chlorophyll.
Q.5. Differentiate between Respiration and Combustion.
Sol.
Respiration: It is a metabolic process that occurs in all organisms. It is considered a biochemical process that occurs within the cells of organisms.
Combustion: It is a chemical process in which the fuel combines with oxygen gas to release energy in the form of heat and light. This heat can be used to produce electricity, run our cars and also for cooking.
Difference between Respiration and Combustion:
| Respiration | Combustion |
| It is a natural process. | It has to be initiated by applying heat. |
| It is a continuous process, while burning is a discontinuous process. | It is a discontinuous process. |
| It is a biochemical process that occurs inside the cells. | It is a chemical process which is non-cellular. |
| It is an enzymatic process. | It is a non-enzymatic process. |
| Chemical bonds slowly break down one by one. | Chemical bonds quickly break down all at once. |
| Occurs through the formation of intermediates. | Does not form intermediates. |
| It is a multi-step process, | It is a single-step process. |
| Releases energy slowly | Releases energy quickly. |
| The energy released during respiration is stored in ATP molecules | The energy is released in the form of heat and light during burning. |
| Water and carbon dioxide are the by-products of respiration. | Carbon dioxide, sulfur dioxide, nitric oxide, oxygen, etc. are the by-products of burning. |
Q.6. Brief out the internal factors affecting the rate of respiration.
Sol. The protoplasm of the cell and the respiratory substance are the main internal factors which affect the rate of respiration.
Protoplasm:
In meristematic cells, the protoplasm is active and is found in the excess by which the rate of respiration in these cells are comparatively more than the rate of respiration in the mature cells.
Respiratory factors:
There are different types of sugar present within the cell-like glucose, fructose, maltose and all these are used immediately in the respiration process. Compared to these conversions of the starch and fats into sugar is necessary before their use. Due to this reason, the process of respiration is delayed.
Age of the cell:
Rate of transpiration is high in young cells compared to that of adult and old cells.
Injury or wound:
Rate of transpiration is increased in injured and damaged tissues.
Q.7. Give the schematic representation of an overall view of Krebs’ cycle.
Sol. The Krebs cycle or Citric acid cycle is a series of enzyme catalysed reactions occurring in the mitochondrial matrix, where acetyl-CoA is oxidised to form carbon dioxide and coenzymes are reduced, which generate ATP in the electron transport chain.
Q.8. Differentiate between Respiration and Photosynthesis.
Sol. Respiration: It is a metabolic process that occurs in all organisms. It is considered a biochemical process that occurs within the cells of organisms.
Photosynthesis: It is a biological process utilized by all green plants to synthesize their own nutrients.
Difference between Respiration and Photosynthesis:
| Photosynthesis | Respiration |
| Occurs only in all green plants, algae, and in some bacteria. | Occurs in all living organisms. |
| The entire process occurs in Chloroplasts. | The entire process occurs in Mitochondria. |
| Carbon dioxide, water, and light energy are the reactants of this process. | Glucose and oxygen are the reactants of this process. |
| Glucose, oxygen, and water are the by-products. | Carbon dioxide, water, and energy (ATP) are the by-products. |
| Undergoes Anabolic Process. | Undergoes Catabolic Process. |
| Producing food and capturing energy. | Oxygen is taken in and carbon dioxide is liberated out. |
| In this process, food is synthesized by capturing energy. | In this process, food particles are broken down to release energy. |
| It is an endothermic reaction as it requires energy. | It is an exergonic reaction as energy is released. |
| This process requires sunlight since photosynthesis occurs only in the presence of sunlight. | This process does not require sunlight since cellular respiration occurs all the time. |
| The chemical reaction of photosynthesis is 6CO2 + 6H2O → C6H12O6+ 6O2. | The chemical reaction of cellular Respiration is C6H12O6 + 6O2 → 6CO2 + 6H2O. |
Q.9. Give the schematic representation of glycolysis?
Sol. Glycolysis is the process in which glucose is broken down to produce energy. It produces two molecules of pyruvate, ATP, NADH and water. The process takes place in the cytosol of the cell cytoplasm, in the presence or absence of oxygen.
The schematic representation of glycolysis
Q.10. Brief out the external factors affecting the rate of respiration.
Sol. External factors affecting the rate of respiration are:
Temperature:
Temperature is the main factor that affects the process of respiration. Increase in temperature increases the rate of respiration. The process of respiration increased in this limit is according to Van’t Hoff’s rule. According to this rule, for every 10C temperature, the rate of respiration becomes double.
Oxygen:
Oxygen is necessary for aerobic respiration. Respiration decreases with decreased available oxygen. When the concentration of oxygen reaches zero, the anaerobic respiration occurs.
Water:
Waterworks as a mediator for anabolic reactions in protoplasm. Water plays an important role in the transport system of plants exchange of gases and in the activation of enzymes. Lack of available water affects the process of respiration. In the presence of water, carbohydrates are converted into soluble sugar and thus increases the rate of respiration.
Light:
In the presence or absence of light, the respiration process occurs uniformly in both the phases. Therefore, light does not affect the process of respiration. However, indirectly light affects the process of respiration, as it controls respiration by raising the temperature of an organism.
Carbon Dioxide:
As the concentration of carbon dioxide increases the rate of respiration decreases. The higher the concentration of carbon dioxide, the lower the process of respiration. This can be clearly observed in the process of seed germination.
Q.11. Write the difference between Glycolysis and Fermentation.
Sol. Difference between Glycolysis and Fermentation:
| Glycolysis | Fermentation |
| It is the first step of aerobic respiration. | It is anaerobic respiration. |
| Glucose is converted into pyruvate. | Pyruvate is converted to alcohol or lactic acid. |
| It produces two molecules of NADH per glucose molecule. | It uses NADH produced during glycolysis. |
| It results in a net gain of 8 ATP. | It results in a net gain of 3 ATP. |
| The pyruvate enters the citric acid cycle. | The pyruvate is converted into ethanol or lactic acid and NAD+ is regenerated. |
| It takes place with or without the presence of oxygen. | It takes place in the presence of oxygen. |
Q.12. Write the difference between Glycolysis and Krebs Cycle.
Sol. Glycolysis – It is an anaerobic process in which a molecule of glucose is converted into two molecules of pyruvic acid. It takes place in the cytoplasm
Krebs Cycle – It is an aerobic process that takes place in the mitochondrial matrix that involves the oxidation of pyruvic acid into water and carbon dioxide.
Given below in a tabular column are the differences between glycolysis and Krebs Cycle.
| Glycolysis | Krebs Cycle |
| The first step in respiration in which glucose is broken down into two molecules of pyruvate. | The second step of respiration in which it degrades pyruvate into inorganic substances. |
| Occurs inside the cytoplasm. | Occurs inside the mitochondria. |
| No carbon dioxide evolved. | Carbon dioxide evolved. |
| It occurs both in aerobic and anaerobic respiration. | It occurs in aerobic respiration only. |
| Oxygen not required for glycolysis. | Oxygen is required for the Krebs Cycle. |
| Occurs as a linear sequence. | Occurs as a cyclic sequence. |
| It is a linear pathway. | It is a cyclic pathway. |
| Two molecules of pyruvic acid are formed. | Carbon dioxide and water are formed. |
| NADH 2 and ATP are formed. | NADH 2, ATP and FADH2 are formed. |
| Consumes two molecules of ATP | Doesn’t consume ATP. |
| Two molecules of ATP and NADH are gained for every molecule of glucose. broken down | Six molecules of NADH and two molecules of FADH2 for every acetyl-CoA oxidised. |
| One molecule of glucose liberates 4 ATP molecules through substrate-level phosphorylation. | Two acetyl residues liberate two ATP and GTP molecules through substrate-level phosphorylation. |
Q.13. What is Glycolysis? List out the importance of Glycolysis.
Sol. Glycolysis is the process in which glucose molecules are broken down to produce energy. It produces two molecules of pyruvate, ATP, NADH and water. The process takes place in the cytosol of the cell cytoplasm, in the presence or absence of oxygen. The process of glycolysis takes place in the cytoplasm of plant and animal cells, where six enzymes are involved in the process. The end products of the glycolysis reaction include 2 pyruvate, 2 ATP and 2 NADH molecules.
The term glycolysis originated from the Greek words- glyco for sugar and lysis for splitting. The scheme of glycolysis was given by Gustav Embden, Otto Meyerhof, and J. Parnas, and is often referred to as the EMP pathway.
Importance of Glycolysis
- Glycolysis is present in all living organisms.
- Glucose is the only source of energy used by cells.
- It is the process in which a glucose molecule is broken down into two molecules of pyruvate.
- Glycolysis produces a net gain of two ATP molecules, two pyruvate molecules and two NADH molecules.
- Glycolysis is a universal central pathway of glucose catabolism, which takes place within the cytoplasm of all the tissues of biological systems leading to the generation of energy in the form of ATP for vital activities
- In plants, glycolysis is the key metabolic component of the respiratory process, which generates energy in the form of ATP.
- Many types of anaerobic microorganisms are entirely dependent on glycolysis
- Mammalian tissues such as renal medulla and brain solely depend on glycolysis for major sources of metabolic energy.
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