Question

The given flowchart shows the different pathways of glucose breakdown. Identify P, Q, R and S.

• A. P- Carbon dioxide, Q - Ethanol, R - Lactic acid, S - Pyruvate
• B. P- Pyruvate, Q - Carbon dioxide, R - Ethanol, S - Lactic acid
• C. P- Lactic acid, Q - Ethanol, R - Pyruvate, S - Carbon dioxide
• D. P- Pyruvate, Q - Ethanol, R - Lactic acid, S - Carbon dioxide

Answer 1

The correct option is B P- Pyruvate, Q - Carbon dioxide, R - Ethanol, S - Lactic acid

In the above pathays mentioned:

• P is pyruvate the 3C molecule formed after glycolysis. This step is common for all the three pathways in respiration which is carried out in the cell cytoplasm.
• Q is carbon dioxide. In the first equation, the pathway shown is aerobic respiration i.e. in the presence of oxygen which takes place in all our body cells. In aerobic respiration, the glucose is completely broken down to carbon dioxide, water , and a large amount of energy is released.
• R is ethanol. In the second equation, the pathway shown is anaerobic respiration i.e. in the absence of oxygen which takes place in the Yeast. In anaerobic respiration, the glucose is broken down to 2C ethanol, carbondioxide and a small amount of energy is released.
• S is lactic acid. In the third equation, the pathway shown is the respiration that takes place in the lack of oxygen in the muscle cells. In the lack of oxygen, the pyruvate is converted to lactate (lactic acid) and energy is released.