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Answer:
Question 2.
Answer: Respiratory substrate. The organic substances, which undergo catabolic reaction in the living cells to release energy during respiration, are known as respiratory substrates. Glucose is the most common substrates used in cellular respiration. Glycogen and sugars other than glucose are broken down to glucose and fed into glycolysis.
Question 3.
Answer: The main steps in aerobic respiration are: - 1. Glycolysis – This takes place in the cytoplasm. 2. The complete oxidation of pyruvate by the stepwise removal of all the hydrogen atoms leaving three molecules of CO2 . This takes place in the mitochondria 3. The passing on of the electrons removed as part of the hydrogen atoms to molecular O2 with simultaneous synthesis of ATP. This also takes place in the mitochondria.
Question 4.
Answer: Tricarboxylic acid cycle, more commonly called as Krebs’ cycle after the scientist Hans Krebs.
The TCA cycle consists of the following steps:
1. The TCA cycle starts with the condensation of acetyl group with oxaloacetic acid (OAA) and water to yield citric acid.
2. The reaction is catalysed by the enzyme citrate synthase and a molecule of CoA is released.
3. It is followed by two successive steps of decarboxylation, leading to the formation of α-ketoglutaric acid and then succinyl-CoA.
During the conversion of succinyl-CoA to succinic acid a molecule of GTP is synthesised. This is a substrate level phosphorylation.
4. In a coupled reaction GTP is converted to GDP with the simultaneous synthesis of ATP from ADP.
The summary equation for this phsae of respiration may be written as:
Pyruvic acid + 4 NAD+ + FAD+ + 2H2o + 2H2O + ADP + Pi -------Mitochondrial Matrix------> 3CO2 + 4NADH + 4H+ + FADH2 + ATP
Question 5.
Answer: (a) Differences between aerobic respiration and anaerobic respiration
(b) Difference between glycolysis and fermentation 
Question 6.
Answer: It is possible to make calculations of the net gain of ATP for every glucose molecule oxidised. But in reality this can remain only a theoretical exercise. These calculations can be made only on certain assumptions that: 1. There is a sequential, orderly pathway functioning, with one substrate forming the next and with glycolysis, TCA cycle and ETS pathway following one after another. 2. The NADH synthesised in glycolysis is transferred into the mitochondria and undergoes oxidative phosphorylation. 3. None of the intermediates in the pathway are utilised to synthesise any other compound. 4. Only glucose is being respired – no other alternative substrates are entering in the pathway at any of the intermediary stages
Question 7.
Answer: Because the respiratory pathway is involved in both anabolism and catabolism, it would hence be better to consider the respiratory pathway as an amphibolic pathway. Fatty acids would be broken down to acetyl CoA before entering the respiratory pathway when it is used as a substrate. But when the organism needs to synthesis fatty acids, acetyl CoA would be withdrawn from the respiratory pathway for it. Hence the respiratory pathway comes into the picture both during breakdown and synthesis of fatty acids. Similarly during breakdown and synthesis of protein too, respiratory intermediates form the link. Breaking down processes within the living organism is catabolism, and synthesis is anabolism.
Question 8.
Answer: Respiratory Quotient (R.Q). The ratio of volume of CO2 evolved to the volume of oxygen consumed per unit time per unit weight. R.Q. indicates the type of respiratory substrate being used and type of respiration being performed R.Q. value is one for aerobic respiration of glucose; more than one for organic acids (e.g. 1.3 for malic acid and 1.14 for succinic acid) less than one for fats (0.7) and proteins (0.85); infinity for anaeobic respiration (as no oxygen is used). It can be measured by respiirometer.
Question 9.
Answer: The generation of ATP from ADP during electron transport system by utilizing the energy obtained during oxidative reaction is called oxidative phosphorylation.
Question 10.
Answer: Anaerobic and aerobic respiration are conducted in many steps and energy is released in steps. The advantages of stepwise release of energy are: 1. It facilitates the utilization of the relatively higher proportion of the energy in ATP synthesis. 2. Activities of enzymes for the different steps may be enhanced or inhibited by specific compounds. This provides a mean of controlling the rate of the pathway and the energy output according to the need of the cell. 3. The same pathway may be utilized for forming intermediates used in the synthesis of other biomolecules like amino acids.
Respiration In Plants
Class 11th Biology CBSE Solution
Ncert Questions
- Differentiate between Respiration and combustion.
- What are respiratory substrates? Name the most common respiratory substrate.…
- What are the main steps in aerobic respiration? Where does it take place?…
- Give the schematic representation of an overall view of Krebs cycle.…
- Distinguish between the following:(a) Aerobic respiration and anaerobic respiration(b)…
- What are the assumptions made during the calculation of net gain of ATP?…
- Discuss "The respiratory pathway is an amphibolic pathway".
- Define R.Q. What is its value for fats?
- What is Oxidative phophorylation.
- What is the significance of step-wise release of energy in respiration?…
Ncert Questions
Question 1.Differentiate between Respiration and combustion.
Answer:
Question 2.
What are respiratory substrates? Name the most common respiratory substrate.
Answer: Respiratory substrate. The organic substances, which undergo catabolic reaction in the living cells to release energy during respiration, are known as respiratory substrates. Glucose is the most common substrates used in cellular respiration. Glycogen and sugars other than glucose are broken down to glucose and fed into glycolysis.
Question 3.
What are the main steps in aerobic respiration? Where does it take place?
Answer: The main steps in aerobic respiration are: - 1. Glycolysis – This takes place in the cytoplasm. 2. The complete oxidation of pyruvate by the stepwise removal of all the hydrogen atoms leaving three molecules of CO2 . This takes place in the mitochondria 3. The passing on of the electrons removed as part of the hydrogen atoms to molecular O2 with simultaneous synthesis of ATP. This also takes place in the mitochondria.
Question 4.
Give the schematic representation of an overall view of Krebs cycle.
Answer: Tricarboxylic acid cycle, more commonly called as Krebs’ cycle after the scientist Hans Krebs.
The TCA cycle consists of the following steps:
1. The TCA cycle starts with the condensation of acetyl group with oxaloacetic acid (OAA) and water to yield citric acid.
2. The reaction is catalysed by the enzyme citrate synthase and a molecule of CoA is released.
3. It is followed by two successive steps of decarboxylation, leading to the formation of α-ketoglutaric acid and then succinyl-CoA.
During the conversion of succinyl-CoA to succinic acid a molecule of GTP is synthesised. This is a substrate level phosphorylation.
4. In a coupled reaction GTP is converted to GDP with the simultaneous synthesis of ATP from ADP.
The summary equation for this phsae of respiration may be written as:
Pyruvic acid + 4 NAD+ + FAD+ + 2H2o + 2H2O + ADP + Pi -------Mitochondrial Matrix------> 3CO2 + 4NADH + 4H+ + FADH2 + ATP
Question 5.
Distinguish between the following:(a) Aerobic respiration and anaerobic respiration(b) Glycolysis and fermentation(c) Glycolysis and citric acid cycle.
Answer: (a) Differences between aerobic respiration and anaerobic respiration
(b) Difference between glycolysis and fermentation Question 6.
What are the assumptions made during the calculation of net gain of ATP?
Answer: It is possible to make calculations of the net gain of ATP for every glucose molecule oxidised. But in reality this can remain only a theoretical exercise. These calculations can be made only on certain assumptions that: 1. There is a sequential, orderly pathway functioning, with one substrate forming the next and with glycolysis, TCA cycle and ETS pathway following one after another. 2. The NADH synthesised in glycolysis is transferred into the mitochondria and undergoes oxidative phosphorylation. 3. None of the intermediates in the pathway are utilised to synthesise any other compound. 4. Only glucose is being respired – no other alternative substrates are entering in the pathway at any of the intermediary stages
Question 7.
Discuss "The respiratory pathway is an amphibolic pathway".
Answer: Because the respiratory pathway is involved in both anabolism and catabolism, it would hence be better to consider the respiratory pathway as an amphibolic pathway. Fatty acids would be broken down to acetyl CoA before entering the respiratory pathway when it is used as a substrate. But when the organism needs to synthesis fatty acids, acetyl CoA would be withdrawn from the respiratory pathway for it. Hence the respiratory pathway comes into the picture both during breakdown and synthesis of fatty acids. Similarly during breakdown and synthesis of protein too, respiratory intermediates form the link. Breaking down processes within the living organism is catabolism, and synthesis is anabolism.
Question 8.
Define R.Q. What is its value for fats?
Answer: Respiratory Quotient (R.Q). The ratio of volume of CO2 evolved to the volume of oxygen consumed per unit time per unit weight. R.Q. indicates the type of respiratory substrate being used and type of respiration being performed R.Q. value is one for aerobic respiration of glucose; more than one for organic acids (e.g. 1.3 for malic acid and 1.14 for succinic acid) less than one for fats (0.7) and proteins (0.85); infinity for anaeobic respiration (as no oxygen is used). It can be measured by respiirometer.
Question 9.
What is Oxidative phophorylation.
Answer: The generation of ATP from ADP during electron transport system by utilizing the energy obtained during oxidative reaction is called oxidative phosphorylation.
Question 10.
What is the significance of step-wise release of energy in respiration?
Answer: Anaerobic and aerobic respiration are conducted in many steps and energy is released in steps. The advantages of stepwise release of energy are: 1. It facilitates the utilization of the relatively higher proportion of the energy in ATP synthesis. 2. Activities of enzymes for the different steps may be enhanced or inhibited by specific compounds. This provides a mean of controlling the rate of the pathway and the energy output according to the need of the cell. 3. The same pathway may be utilized for forming intermediates used in the synthesis of other biomolecules like amino acids.