An unfertilized human ovum has

Options

A. X and Y chromosomes
B. X and X chromosomes
C. X in some and Y in other s
D. Only one X- chromosome.

Answer

To answer the question "An unfertilized human ovum has:", we will analyze the characteristics of human gametes, specifically focusing on the female gamete, which is the ovum.

### Step-by-Step Solution:

1. **Understanding Gametes**:
- Gametes are reproductive cells that carry genetic information. In humans, there are two types of gametes: sperm (male) and ovum (female).

2. **Chromosomal Composition**:
- Human cells typically have 46 chromosomes, which are arranged in 23 pairs. Out of these, 22 pairs are autosomes, and one pair consists of sex chromosomes.

3. **Identifying the Female Gamete**:
- The ovum is the female gamete. In females, the sex chromosomes are represented as XX, meaning that females have two X chromosomes.

4. **Chromosomes in an Unfertilized Ovum**:
- When an ovum is formed, it undergoes meiosis, which reduces the chromosome number by half. Therefore, an unfertilized human ovum contains 23 chromosomes in total.
- Out of these 23 chromosomes, 22 are autosomes, and 1 is a sex chromosome.

5. **Determining the Type of Sex Chromosome**:
- Since the ovum is a female gamete, it will carry only one X chromosome. The Y chromosome is only present in male gametes (sperm).

6. **Conclusion**:
- Therefore, an unfertilized human ovum has 23 chromosomes in total, with one of them being an X chromosome.

### Final Answer:
An unfertilized human ovum has 23 chromosomes, including one X chromosome.

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