Question

A primary spermatocyte after first meiotic division leads to the formation of secondary spermatocytes. These are:

• A. Two equal haploid cells
• B. Two unequal haploid cells
• C. Two diploid cells
• D. Four diploid cells

Hint:

In spermatogenesis, one primary spermatocyte ultimately forms four equal-sized sperms, whereas in oogenesis only one functional ovum is produced.

Answer 1

The Correct Option is A

Concept: Spermatogenesis is the process of formation of male gametes (sperms) inside the seminiferous tubules of testes. During this process, diploid germ cells undergo meiotic divisions to produce haploid cells. Meiosis-I is called reductional division because it reduces the chromosome number from diploid (\(2n\)) to haploid (\(n\)).

Step 1: Understanding the nature of primary spermatocyte.
A primary spermatocyte is formed from spermatogonia. It is diploid in nature, which means it contains \(2n\) chromosomes. These cells are specifically meant to undergo meiotic divisions for gamete formation.

Step 2: Analyzing the first meiotic division.
The primary spermatocyte undergoes Meiosis-I. During this division, homologous chromosomes separate from each other and move to opposite poles of the cell. Since chromosome number becomes half after this division, the resulting daughter cells become haploid.

Step 3: Determining the number and nature of daughter cells formed.
One primary spermatocyte divides to produce two daughter cells known as secondary spermatocytes. Each secondary spermatocyte contains haploid number of chromosomes (\(n\)).

Step 4: Understanding cytokinesis during spermatogenesis.
In males, cytokinesis during spermatogenesis is equal. This means the cytoplasm divides equally between the two daughter cells. Therefore, both secondary spermatocytes are nearly equal in size.

Step 5: Eliminating incorrect options.
- Option (B) is incorrect because unequal division occurs in oogenesis, not spermatogenesis.
- Option (C) is incorrect because secondary spermatocytes are haploid, not diploid.
- Option (D) is incorrect because Meiosis-I produces only two cells, not four. Hence, the correct answer is two equal haploid cells.