Question

A pregnant woman asked her doctor about the chances of her baby being a boy. The doctor said that there was an equal chance of the baby being a boy or a girl. Complete the diagram below to explain why the doctor said this. Use X and Y to represent the sex chromosomes. Male Female parents ................................... x ....................................... gametes ............. ................ x ................ ................. offspring genotypes ............................................................................................................... offspring phenotypes

Answer 1

Step-by-step explanation:

The doctor's statement that there is an equal chance of the baby being a boy or a girl is based on the principle of Mendelian inheritance and the way in which sex determination works in humans. In this system, males have one X and one Y chromosome (XY), while females have two X chromosomes (XX).

Here's a simplified diagram to illustrate this:

Parents:

- Male: XY

- Female: XX

Gametes (sperm and egg):

- Male produces two types of gametes: X (sperm with X chromosome) and Y (sperm with Y chromosome).

- Female produces one type of gamete: X (egg with X chromosome).

Offspring Genotypes:

- When a sperm carrying an X chromosome fertilizes an egg with an X chromosome, the genotype is XX, resulting in a female offspring.

- When a sperm carrying a Y chromosome fertilizes an egg with an X chromosome, the genotype is XY, resulting in a male offspring.

Offspring Phenotypes:

- XX genotype leads to the female phenotype.

- XY genotype leads to the male phenotype.

This illustrates that, when an X-carrying sperm fertilizes an egg (XX) or a Y-carrying sperm fertilizes an egg (XY), there is an equal probability of the baby being a boy (XY) or a girl (XX) because it depends on the combination of the X or Y chromosome from the father's sperm and the X chromosome from the mother's egg.