Question

In Pinus; the pollen grain has 6 chromosomes then in its endosperm will have

• A. 12
• B. 18
• C. 6
• D. 24

Answer 1

The Correct Option is C

To determine the number of chromosomes in the endosperm of Pinus when the pollen grain has 6 chromosomes, we need to understand the basic plant reproductive process, particularly in gymnosperms like Pinus.

Here's the step-by-step explanation:

1. Understanding the Pollen Grain:
   • The pollen grain represents the male gametophyte and in Pinus, it is haploid. This means it has half the number of chromosomes found in the diploid cell.
2. Haploid and Diploid Relationship:
   • If the pollen grain (haploid) has 6 chromosomes, the diploid sporophytic cell will have 2 \times 6 = 12 chromosomes, because the sporophyte is diploid in nature, having two sets of chromosomes.
3. Formation of Endosperm in Gymnosperms:
   • In gymnosperms like Pinus, the endosperm is actually part of the female gametophyte and is formed before fertilization. It remains haploid.
   • Therefore, the endosperm will have the same number of chromosomes as the gametophyte. Since the gametophyte is haploid in Pinus, it will have 6 chromosomes, matching the pollen grain.
4. Conclusion:
   • The endosperm in Pinus will have 6 chromosomes, which corresponds to the haploid number calculated from the pollen grain.

Therefore, the correct answer is 6 chromosomes for the endosperm.