Read the given statements.(i) Outer exine is made up of sporopollenin....
In a mature pollen grain, the generative cell is smaller and the tube (or vegetative) cell is larger. In the later stages of development of pollen grain, callose dissolves and the naked generative cell comes to lie freely in the cytoplasm of the tube cell. The tube cell has a cytoplasm which is rich in the food reserve (starch, protein, fat with mostly unsaturated fatty acids).
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Read the given statements.(i) Outer exine is made up of sporopollenin....
The correct answer is option C, which states that statements (iii) and (iv) are not true regarding the structure of a pollen grain. Let's analyze each statement in detail to understand why this answer is correct.
(i) Outer exine is made up of sporopollenin:
- This statement is true. The outermost layer of the pollen grain, called the exine, is composed of a tough and resistant material called sporopollenin. Sporopollenin provides protection to the pollen grain against environmental stresses.
(ii) Inner intine is pecto-cellulosic in nature:
- This statement is not true. The innermost layer of the pollen grain, called the intine, is primarily composed of cellulose. Pectin is a component of the middle lamella, which is present between adjacent pollen grains, but it is not a major constituent of the intine.
(iii) Generative cell is bigger and contains abundant food reserve:
- This statement is not true. The generative cell is actually smaller in size compared to the vegetative cell. The generative cell is responsible for giving rise to the sperm cells, while the vegetative cell provides nourishment to the generative cell and helps in its movement.
(iv) Vegetative cell is small and floats in the cytoplasm of the generative cell:
- This statement is not true. The vegetative cell is larger in size compared to the generative cell. It does not float in the cytoplasm of the generative cell but remains attached to it. The vegetative cell provides nourishment and energy to the generative cell during pollen germination.
In conclusion, statements (iii) and (iv) are not true regarding the structure of a pollen grain. The generative cell is smaller and does not contain abundant food reserves, while the vegetative cell is larger and remains attached to the generative cell during pollen germination.
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