Which on of the following is haploid?

Options

A. Oogonia
B. Primary oocyte
C. Secondary oocyte
D. primary spermatocyte

Answer

To determine which of the following options is haploid, we need to understand the concept of ploidy and analyze each option given. Here’s a step-by-step solution:

### Step 1: Understand the term "haploid"
- **Haploid** refers to a cell that has only one set of chromosomes, denoted as "N". In humans, haploid cells are typically gametes (sperm and egg cells).

### Step 2: Analyze the options provided
The options given are:
1. Oogonia
2. Primary oocyte
3. Secondary oocyte
4. Primary spermatocyte

### Step 3: Determine the ploidy of each option
1. **Oogonia**:
- Oogonia are the precursor cells in oogenesis and are diploid (2N).

2. **Primary oocyte**:
- Primary oocytes are also diploid (2N) as they have not yet undergone meiosis.

3. **Secondary oocyte**:
- The secondary oocyte is formed after the first meiotic division, resulting in a haploid cell (N).

4. **Primary spermatocyte**:
- Primary spermatocytes are diploid (2N) as they arise from spermatogonia and have not yet undergone meiosis.

### Step 4: Identify the haploid cell
From the analysis:
- Oogonia: 2N (diploid)
- Primary oocyte: 2N (diploid)
- Secondary oocyte: N (haploid)
- Primary spermatocyte: 2N (diploid)

The only haploid cell among the options is the **secondary oocyte**.

### Conclusion
The correct answer is **C. Secondary oocyte**, as it is the only haploid cell listed.

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