Which diagram illustrates fertillsation that would most likely lead to the development of a normal human male?

Options

A.
B.
C.
D.

Answer

To determine which diagram illustrates fertilization that would most likely lead to the development of a normal human male, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Fertilization**: Fertilization is the process where a male gamete (sperm) fuses with a female gamete (egg) to form a zygote. This zygote will develop into an embryo and eventually a child.

2. **Identify Chromosomes**: In humans, there are 23 pairs of chromosomes. Out of these, 22 pairs are autosomes, and the 23rd pair consists of sex chromosomes (XX for females and XY for males).

3. **Determine Male Karyotype**: For a normal human male, the karyotype must include 22 pairs of autosomes and one pair of sex chromosomes that are XY. This means that the sperm must contribute a Y chromosome.

4. **Analyze the Diagrams**: Look at the provided diagrams and identify which one shows the sperm contributing a Y chromosome and the egg contributing an X chromosome. This combination (XY) will lead to the development of a male.

5. **Eliminate Incorrect Options**: The first two diagrams are incorrect because they involve the fusion of gametes that do not lead to a normal male child. If the sperm provides an X chromosome instead of a Y chromosome, the result will be a female (XX).

6. **Select the Correct Diagram**: The correct diagram will show the sperm (with Y chromosome) fertilizing the egg (with X chromosome), resulting in an XY combination. This is the only scenario that will lead to a normal human male.

### Conclusion:
The correct answer is the diagram that shows the sperm contributing a Y chromosome and the egg contributing an X chromosome, resulting in an XY karyotype for a normal male child.

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