This set of Biology Multiple Choice Questions & Answers (MCQs) focuses on “Plants Respiration – Amphibolic Pathway”.
1. How many major components are there in Complex V of ETS?
Explanation: The energy released during the electron transport system is utilised in synthesising ATP with the help of ATP synthase-Complex V. This complex consists of two major components F1 and F0.
2. What kind of protein is F1 that is present in Complex V?
a) Peripheral protein
b) Embedded protein
c) Integral protein
d) Membrane less protein
Explanation: The F1 headpiece that is present in the Complex V is a peripheral membrane protein complex and contains the site for synthesis of ATP from ADP and inorganic phosphate.
3. What kind of compound is F0 particle?
a) Peripheral protein
b) Cutaneous protein
c) Embedded protein
d) Integral protein
Explanation: Fo is an integral membrane protein complex that forms the channel through which protons across the inner membrane. It is a component of Complex V of ETS.
4. For each ATP produced, how many protons pass through the intermembrane space?
Explanation: The passage of protons through the channel is coupled to the catalytic site of the F1 component for the production of ATP. For each ATP produced, two protons pass through the F0 from the intermembrane space to the matrix down the electrochemical proton gradient.
5. Which of the following is the favoured substance for respiration?
Explanation: Glucose is the favoured substrate for respiration because glucose is a carbohydrate and is readily available in the cells through the food that cell intakes. It also releases a large amount of energy on its oxidation.
6. For the fats to be respired, what are they broken into?
a) Glycerol and fatty acids
b) Glycerol and ethanol
c) Fatty acids only
d) Glycerol only
Explanation: Fats would need to be broken down into glycerol and fatty acids first. If fatty acids were to be respired they would first be degraded to acetyl CoA and enter the pathway.
7. Glycerol would enter the pathway after being converted to malic acid.
Explanation: Glycerol would enter the pathway after being converted to PGAL which is 3-phosphoglyceraldehyde. Apart from glucose, other substances can be respired but then they do not enter the respiratory pathway at the first step.
8. Which of the following are responsible for the degradation of proteins?
Explanation: Proteases are the enzymes which are responsible for the degradation of proteins. These enzymes break the bonds between the proteins and release amino acids which then enter the respiratory pathway.
9. Which pathway was respiration traditionally considered as?
a) Anabolic pathway
b) Catabolic pathway
c) Amphibolic pathway
d) Bolic pathway
Explanation: Since respiration involves the breakdown of substrates, the respiratory process has traditionally been considered as a catabolic process and the respiratory pathway as a catabolic pathway.
10. What would happen if organisms need to synthesise fatty acids which had already broken down into acetyl CoA?
a) Acetyl CoA would be withdrawn from the pathway
b) Acetyl CoA would be further broken down
c) Ethanol would be released
d) Glycerol would be released
Explanation: When fatty acids are to be used as substrates, then they would be broken down to acetyl CoA before entering the respiratory pathway, but when organisms need to synthesise fatty acids, acetyl CoA would be withdrawn from the respiratory pathway for it.
11. The respiratory pathway comes into the picture in both the breakdown and synthesis of fatty acids.
Explanation: The respiratory pathway comes into the picture in both the breakdown and synthesis of fatty acids. Similarly, during breakdown and synthesis of proteins too, respiratory intermediates form the link.
12. What is catabolism?
a) Joining of substances
b) Breaking down processes
c) Continuous processes
d) Discontinuous processes
Explanation: Catabolism refers to the breaking down processes that occur within the living organisms. Catabolic reactions include glycolysis, the tricarboxylic citric acid cycle, breakdown of fatty acids, etc.
13. What is meant by anabolism?
a) Synthesis of some molecules
b) Breaking down of molecules
c) Joining of bonds
d) Shifting of bonds
Explanation: Anabolism refers to the synthesis of some new molecules, for example, the reaction of glycerol with fatty acids to make lipids, photosynthesis, etc.
14. In mitochondria, which of the following is the site for the oxidation-reduction reaction?
a) Inner membrane
b) Outer membrane
Explanation: In mitochondria, cristae re the sites for oxidation-reduction reaction. They produce cellular energy in the form of ATP, hence they are called as powerhouse of the cell.
15. What is an amphibolic pathway?
a) Breaking down processes
b) Another name for catabolic processes
c) Both anabolic and catabolic processes
d) Another name for anabolic processes
Explanation: As the respiratory pathway is involved in both anabolism and catabolism, it is better to consider the respiratory pathway is an amphibolic pathway. Therefore, according to new studies, respiration is treated as an amphibolic pathway and not as a catabolic pathway as according to traditional studies.
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