B1.2 B

Question	Answer
What decides an embryo's sex?	A fertilised egg cell has 23 pairs of chromosomes. Pair 23 are the sex chromosomes. Males have an X and Y chromosome but females have two X chromosomes.
What makes a baby male?	Male and female embryos are very alike until about 6 weeks old. Then a male embryo's testes start to develop. This is caused by a gene on the Y chromosome - the SRY gene.
How different sex's develop in the womb?	.Androgen make the embryo develop male characteristics. If there is no male sex hormone present, the embryo develops ovaries, clitoris and vagina of a female.
What are hormones?	Hormones are a group of proteins that control many process in the cells. Tiny amounts of hormones are made by different parts of the body. They travel to their target cells in the bloodstream.

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	Created by Jaweria Khalid about 7 years ago