▶️ Answer/Explanation
✅ Answer: (B)
▶️ Answer/Explanation
The process begins when vigorous exercise triggers anaerobic respiration (1) because oxygen demand exceeds supply. This metabolic pathway converts glucose into lactic acid (3), which accumulates in the muscle tissues and creates an oxygen debt (4). To “repay” this debt after exercise stops, the body maintains faster and deeper breathing (2) to take in extra oxygen. This supplemental oxygen then facilitates the aerobic respiration of lactic acid (5) in the liver, breaking it down into carbon dioxide and water. This logical progression from the cause of the debt to its physiological resolution confirms the sequence.
✅ Answer: (A)
▶️ Answer/Explanation
To solve this, we compare the balanced equations for both types of respiration in yeast. In aerobic respiration, one molecule of glucose reacts with oxygen to produce $6$ molecules of $CO_{2}$ ($C_{6}H_{12}O_{6} + 6O_{2} \rightarrow 6CO_{2} + 6H_{2}O$). In anaerobic respiration (fermentation), yeast breaks down one molecule of glucose into ethanol and only $2$ molecules of $CO_{2}$ ($C_{6}H_{12}O_{6} \rightarrow 2C_{2}H_{5}OH + 2CO_{2}$). By subtracting the anaerobic yield from the aerobic yield ($6 – 2 = 4$), we find that aerobic respiration produces $4$ additional molecules of carbon dioxide per glucose molecule.
✅ Answer: (C)