Question

Which of the following statements are correct?

1. pyruvate can be converted into ethanol and carbon dioxide by yeast. 
2. fermentation takes place in the case of aerobic bacteria.
3. fermentation takes place in mitochondria.
4. fermentation is a form of anaerobic respiration.

Options

• (i) and (iii)

• (ii) and (iv)

• (ii) and (iii)

• (i) and (iv)

Answer 1

(i) and (iv)

Explanation:

The correct statements are (i) and (iv). This is because fermentation is a classic example of anaerobic respiration, meaning it occurs entirely in the absence of oxygen. During this process in yeast, the three-carbon molecule pyruvate is broken down within the cell’s cytoplasm into ethanol and carbon dioxide, rather than entering the mitochondria. Conversely, statements (ii) and (iii) are incorrect because fermentation is characteristic of anaerobic organisms (not aerobic bacteria) and it takes place completely outside the mitochondria, which are strictly reserved for oxygen-dependent aerobic respiration.