of chromosomes carried in the human sperm cell determine the sex
of the baby that will develop from the fertilized egg. Each egg
carries an X chromosome. A sperm may carry either an X or a Y chromosome.
If an X-bearing sperm fertilizes the egg, a female results (XX).
A male is formed when a Y-bearing sperm fertilizes the egg (XY).
wish to study human chromosomes, they sometimes photograph the chromosomes
through a microscope. After these photographs are enlarged, the
chromoomes are cut out and arranged in pairs. The resulting product
is called a karyotype.