Humans have 23 pairs of chromosome in every body cell. Even one extra chromosome causes death or serious disorders. For example,
an extra copy of chromosome 21 causes Down syndrome. Which of the following are affected in a human being with an extra chromosome? Choose the 3 items that apply.
Yes, it is possible for a father and son to suffer from haemophilia. Most people who have hemophilia are born with it. It almost always is inherited (passed down) from a parent to a child.
