Exams › NEET › Biology › Respiration in Plants
76 questions with worked solutions.
Answer: Diagram depicts the basic process of both oxidative as well as photosynthetic phosphorylation. However, the proton concentration should be high inside and low outside
The diagram represents the common mechanism used in both oxidative and photosynthetic phosphorylation: an electron transport chain builds a proton gradient that drives ATP synthase. The incorrect part is the proton distribution; in these systems, protons accumulate on one side of the membrane, creating a high-to-low gradient across it.
Q2. Oxidative phosphorylation involves simultaneous oxidation and phosphorylation to finally form
Answer: ATP
Oxidative phosphorylation uses energy released by electron transport to add phosphate to ADP. The end product of this phosphorylation step is ATP, the cell’s main usable energy molecule.
Answer: acetyl CoA
Pyruvate from glycolysis is converted in the link reaction to acetyl CoA, which then combines with oxaloacetate to start the Krebs cycle. This makes acetyl CoA the connecting link between glycolysis and the citric acid cycle.
Answer: mitochondria
The Krebs cycle is a stage of aerobic respiration that takes place in the mitochondrial matrix. Mitochondria are the organelles responsible for most ATP production in eukaryotic cells.
Q5. Which of the following is essential for conversion of pyruvic acid into acetyl Co-A?
Answer: All of these
Conversion of pyruvate to acetyl-CoA is carried out by the pyruvate dehydrogenase complex, which requires multiple cofactors. Lipoic acid, NAD, and TPP all participate in the reaction, so the correct choice is all of these.
Q6. Terminal cytochrome of respiratory chain which donates electrons to oxygen is
Answer: Cyt. a₃
Cytochrome a₃ is part of cytochrome c oxidase (Complex IV), the terminal enzyme of the respiratory chain. It is the component that passes electrons to oxygen, reducing it to water.
Q7. End product of citric acid/Krebs cycle is
Answer: CO₂ + H₂O
The citric acid (Krebs) cycle breaks down acetyl-CoA completely, releasing carbon dioxide as the carbon atoms are oxidized. In aerobic respiration, the overall end products are carbon dioxide and water.
Q8. Oxidative phosphorylation is production of
Answer: ATP in respiration
Oxidative phosphorylation is the stage of cellular respiration where energy from electron transport is used to make ATP. It occurs after electrons pass through the respiratory chain and the resulting proton gradient powers ATP synthase.
Q9. Respiratory Quotient (RQ) value of tripalmitin is:
Answer: 0.7
Respiratory quotient is the ratio of CO2 produced to O2 consumed. Tripalmitin is a fat, and fats typically have an RQ around 0.7 because they require more oxygen for oxidation than carbohydrates.
Q10. Respiratory quotient (R.Q.) for fatty acid is
Answer: < 1
Fatty acids are more reduced than carbohydrates, so their complete oxidation consumes relatively more oxygen and produces less carbon dioxide per unit oxygen used. Therefore, the respiratory quotient is less than 1.
Q11. Apparatus to measure rate of respiration and R.Q. is
Answer: Respirometer
A respirometer is designed to measure the rate of respiration by detecting oxygen consumption. It can also be used to determine R.Q. by comparing oxygen used with carbon dioxide produced.
Q12. R.Q. is
Answer: CO₂/O₂
Respiratory quotient (RQ) is defined as the amount of CO₂ produced divided by the amount of O₂ consumed. For carbohydrate metabolism, this ratio is 1, which corresponds to CO₂/O₂.
Q13. R.Q. is ratio of
Answer: CO₂ produced to O₂ consumed
The respiratory quotient (RQ) is defined as the amount of CO₂ produced divided by the amount of O₂ consumed. This ratio helps indicate which substrate is being respired.
Q14. Series of reactions which can convert fatty acids to sugars in plants but not in animals is
Answer: glyoxylate cycle
The glyoxylate cycle bypasses the decarboxylation steps of the Krebs cycle, so carbon from fatty acids can be conserved and converted into sugars in plants. Animals do not have this cycle, so they cannot make net glucose from fatty acids this way.
Answer: NADH
NADH is produced in glycolysis and the citric acid cycle, then carries electrons to the electron transport chain. In aerobic respiration diagrams, it is the key product linking the first two pathways to the third.
Answer: Acetyl CoA
Acetyl CoA is the common metabolic intermediate produced from carbohydrates, fats, and many proteins before entering the citric acid cycle. It serves as the central link between these breakdown pathways and aerobic respiration.
Q17. Net gain of ATP molecules during aerobic respiration is
Answer: 38 molecules
In the classic textbook accounting, aerobic respiration of one glucose molecule yields 38 ATP in total. This total comes from ATP formed directly in glycolysis and the Krebs cycle plus the larger amount produced during oxidative phosphorylation.
Q18. Maximum amount of energy/ATP is liberated on oxidation of
Answer: fats
Fats are the most energy-rich biomolecules because they contain many C–H bonds and are highly reduced, so their complete oxidation releases more energy than carbohydrates or proteins. Vitamins do not serve as major energy sources.
Answer: Hexokinase
Hexokinase catalyzes the phosphorylation of glucose to glucose-6-phosphate, which is the first irreversible step of glycolysis. This reaction uses ATP and helps trap glucose inside the cell for further metabolism.
Q20. Which of these statements is incorrect?
Answer: Oxidative phosphorylation takes place in outer mitochondrial membrane
Oxidative phosphorylation occurs on the inner mitochondrial membrane, where the electron transport chain and ATP synthase are located. The outer membrane is not the site of this process, so that statement is incorrect.