Read the given statements.
(i) Outer exine is made up of sporopollenin.
(ii) Inner intine is pecto-cellulosic in nature
(iii) Generative cell is bigger and contains abundant food reserve
(iv) Vegetative cell is small and floats in the cytoplasm of the generative cell.
Which of the given statements are not true regarding structure of pollen grain?

Options

A. (i) and (ii)
B. (ii) and (iii)
C. (iii) and (iv)
D. (i) and (iv)

Explanation

To determine which statements regarding the structure of pollen grains are not true, let's analyze each statement one by one:

1. **Statement (i): Outer exine is made up of sporopollenin.**
- This statement is true. The outer layer of the pollen grain, known as the exine, is indeed composed of sporopollenin, which is a tough and resistant biopolymer.

2. **Statement (ii): Inner intine is pecto-cellulosic in nature.**
- This statement is also true. The inner layer of the pollen grain, called the intine, is primarily made up of pectin and cellulose, making it pecto-cellulosic.

3. **Statement (iii): Generative cell is bigger and contains abundant food reserve.**
- This statement is not true. The generative cell is actually smaller than the vegetative cell and does not contain abundant food reserves. The vegetative cell is larger and contains the food reserves necessary for the pollen grain.

4. **Statement (iv): Vegetative cell is small and floats in the cytoplasm of the generative cell.**
- This statement is also not true. The vegetative cell is larger and does not float in the cytoplasm of the generative cell; rather, the generative cell is located within the vegetative cell.

**Conclusion:**
The statements that are not true regarding the structure of pollen grain are:
- Statement (iii): "Generative cell is bigger and contains abundant food reserve."
- Statement (iv): "Vegetative cell is small and floats in the cytoplasm of the generative cell."