Which of the following statements about the cell is correct? MCQ with Answer and Explanation

Explanation:
When oxygen is limiting, pyruvate from glycolysis is reduced to lactic acid (lactate) by lactate dehydrogenase, regenerating NAD⁺ to allow glycolysis to continue. In yeast, pyruvate is converted to ethanol and CO₂ (alcoholic fermentation). Muscle cells lack alcohol dehydrogenase.

Explanation:
Scurvy is vitamin C deficiency; night blindness is vitamin A deficiency. Beriberi is due to vitamin B₁ deficiency, not D. So 1 and 3 are correct.

Explanation:
The small intestine, especially the jejunum and ileum, is the major site for absorption of nutrients due to its large surface area from villi and microvilli. Stomach absorbs some water, alcohol, and drugs. Large intestine absorbs water and electrolytes. Esophagus is a conduit. The small intestine receives bile and pancreatic juice for digestion.