What is the purpose of the micropyle in a seed?

The correct answer is Option (2) → To allow the entry of oxygen and water during germination

The micropyle is the small opening at the tip of the ovule, where the integuments do not cover the nucellus. When the ovule becomes a seed, the integuments harden into the seed coat, but the micropyle stays open as a small pore in the seed coat.

Option (1) To reduce the water content of the seed during maturation — Incorrect. A seed does lose water as it matures and becomes relatively dry. This drying takes place in the whole seed as part of maturation. The micropyle is an opening that later lets water in, so it does not serve to reduce the water content.

Option (2) To allow the entry of oxygen and water during germination — Correct. A germinating embryo needs water to become active again and oxygen for respiration. The hard seed coat does not let them in easily, so they enter through the micropyle. This is the purpose of the micropyle in a seed.

Option (3) To maintain dormancy in the embryo — Incorrect. Dormancy is a state of inactivity of the embryo in which its general metabolic activity slows down. It depends on the condition of the embryo, not on a pore in the seed coat.

NCERT Extract:
Seed – “… Integuments of ovules harden as tough protective seed coats (Figure 1.15a). The micropyle remains as a small pore in the seed coat. This facilitates entry of oxygen and water into the seed during germination. As the seed matures, its water content is reduced and seeds become relatively dry (10-15 per cent moisture by mass). The general metabolic activity of the embryo slows down. The embryo may enter a state of inactivity called dormancy, or if favourable conditions are available (adequate moisture, oxygen and suitable temperature), they germinate.”