NEET Biology: Respiration questions with solutions

Q1. Which of the following steps of respiration is amphibolic?

1. Glycolysis
2. Oxidative decarboxylation of pyruvate
3. TCA cycle
4. Oxidative phosphorylation

Answer: TCA cycle

The TCA cycle is amphibolic because it oxidizes acetyl-CoA to generate energy and also provides intermediates used in biosynthesis. The other steps are mainly catabolic energy-yielding processes.

Q2. Anaerobic process that takes place after glycolysis is called as

1. TCA
2. Calvin cycle
3. Krebs cycle
4. Fermentation

Answer: Fermentation

After glycolysis, if oxygen is unavailable, cells use fermentation to recycle NAD+ and allow glycolysis to continue. TCA/Krebs cycles are aerobic processes, while the Calvin cycle is part of photosynthesis.

Q3. During respiration there is

1. gain in dry weight
2. loss in dry weight
3. no change in dry weight
4. increase in the overall weight

Answer: loss in dry weight

During respiration, organic food is oxidized to release energy, producing carbon dioxide and water. Since stored food is consumed, the organism’s dry mass decreases.

Q4. The energy wastage occurs during

1. Dark respiration
2. Photosynthesis
3. Glycolysis
4. Photorespiration

Answer: Photorespiration

Photorespiration wastes energy because it uses ATP and releases previously fixed carbon as CO2, lowering the overall efficiency of photosynthesis. Unlike normal photosynthesis, it does not contribute to net sugar production.

Q5. The first phase in the breakdown of glucose in animals cells is

1. Krebs cycle
2. Glycolysis
3. Electrons transport system
4. Lipid biosynthesis

Answer: Glycolysis

Glycolysis is the first stage of glucose breakdown in animal cells, occurring in the cytoplasm and converting glucose into pyruvate. The Krebs cycle and electron transport system happen later, after glycolysis has already begun energy extraction.

Q6. When a molecule of pyruvic acid is subjected to anaerobic oxidation and forms lactic acid, there is

1. Loss of 3 ATP molecules
2. Loss of 6 ATP molecules
3. Gain of 2 ATP molecules
4. Gain of 4 ATP molecules

Answer: Gain of 2 ATP molecules

Pyruvic acid is reduced to lactic acid during anaerobic conditions to regenerate NAD+, but this step does not directly produce ATP. The net gain of 2 ATP comes from glycolysis, which yields 4 ATP but uses 2 ATP earlier in the pathway.