Answer:There are two chromosomes which determine gender. These are called the sex chromosomes and there are two types, the X and the Y chromosome. Females have two X chromosomes whereas males have one X and one Y chromosome. The X chromosome is relatively large compared to the Y (which is much smaller) and contains many genes. The Y chromosome on the other hand only contains a few genes. The female always passes on to her offspring the X chromosome from the egg (female gamete). The male can pass on either the Y or the X chromosome from the sperm (male gamete). If the male passes on the X chromosome then the growing embryo will develop into a girls. If the male passes on the Y chromosome then the growing embryo will develop into a boy. Therefore gender depends on whether the sperm which fertilizes the egg is carrying an X or a Y chromosome.
