Which is false?
(a) Pro-ubisch bodies when coated with sporopollenin become ubisch bodies
(b) The nucleus of tapetal cell divides by mitosis and endomitosis
(c) The fibrous thickening of endothecium is made of suberin
(d) None of the above

Options

A. Pro-ubisch bodies when coated coated with sporopollenin become ubisch bodies
B. The nucleus of tapetal cell divides by mitosis and endomitosis
C. The fibrous thickening of endothecium is made of suberin.
D. None of the above.

Answer

To determine which statement is false, let's analyze each option step by step:

1. **Statement (a)**: "Pro-ubisch bodies when coated with sporopollenin become ubisch bodies."
- Pro-ubisch bodies are indeed found in pollen grains. When they are coated with sporopollenin, a highly resistant material, they transform into ubisch bodies. This process is essential for the development of pollen grains and the growth of the pollen tube. Therefore, this statement is **true**.

**Hint**: Look for the role of sporopollenin in pollen grain development.

2. **Statement (b)**: "The nucleus of tapetal cell divides by mitosis and endomitosis."
- The nucleus of the tapetal cell is typically polyploid and does undergo mitosis. However, it does not usually divide by endomitosis. Endomitosis is a process where the nucleus replicates its DNA without cell division, leading to a multinucleated condition. While tapetal cells can have multiple nuclei, the statement suggests that they divide by endomitosis, which is misleading. Thus, this statement is **false**.

**Hint**: Consider the division processes of tapetal cells and the significance of endomitosis.

3. **Statement (c)**: "The fibrous thickening of endothecium is made of suberin."
- The endothecium is a layer in the anther wall, and its fibrous thickening is primarily composed of alpha-cellulose, not suberin. Suberin is a waxy substance found in other plant tissues, but it is not the main component of the endothecium's fibrous thickening. Therefore, this statement is also **false**.

**Hint**: Identify the correct composition of the endothecium's fibrous thickening.

4. **Statement (d)**: "None of the above."
- Since we have identified that both statements (b) and (c) are false, this option cannot be correct.

**Conclusion**: The false statement is (c) "The fibrous thickening of endothecium is made of suberin."

### Summary of Findings:
- (a) True
- (b) False
- (c) False
- (d) None of the above (False)

### Final Answer:
The false statement is (c) "The fibrous thickening of endothecium is made of suberin."