Which of the following engage in lactate fermentation ?

Options

A. Lactobacillus cells
B. Muscle cells
C. Sulphate-reducing bacteria
D. Both (a) and (b)

Answer

**Step-by-Step Solution:**

1. **Understanding Lactate Fermentation**:
- Lactate fermentation is a type of anaerobic respiration where glucose is converted into lactic acid in the absence of oxygen. This process is important for certain organisms and during specific conditions in some cells.

2. **Identifying the Organisms**:
- The question provides four options:
- A) Lactobacillus cells (bacteria)
- B) Muscle cells (human cells)
- C) Sulphur-reducing bacteria
- D) Both A and B

3. **Analyzing Lactobacillus Cells**:
- Lactobacillus is a type of bacteria that is well-known for its role in fermentation, particularly in the production of yogurt and curd from milk. It ferments lactose (the sugar in milk) into lactic acid, which is a classic example of lactate fermentation.

4. **Analyzing Muscle Cells**:
- Muscle cells undergo lactate fermentation during intense exercise when oxygen levels are low. This leads to the conversion of glucose into lactic acid, providing a quick source of energy for muscle contraction.

5. **Evaluating the Other Option**:
- Sulphur-reducing bacteria do not engage in lactate fermentation. They typically use different metabolic pathways that do not involve the production of lactic acid.

6. **Conclusion**:
- Since both Lactobacillus cells and muscle cells are involved in lactate fermentation, the correct answer is **D) Both A and B**.