i'm struggling with bio. Help anyone?

Question

Hemophilia in humans causes them to bleed a lot. Their blood struggles to clot. This is more 

    present in the male population. A man with hemophilia wants to have children with a woman 

    who is a carrier for the gene.  

1. What type of inheritance is this, and how do you know?

Answer 1

Since the passage mentions that men are more likely to get hemophilia and that women can be carriers, we know this is X-linked recessive inheritance.

Explanation:

Hemophilia s more present in the male population because the affected gene is located on the X chromosome. Since males only have one X chromosome, they only need one copy of the altered gene in order to get hemophilia. On the other hand, females have two copies of the X chromosome, so they would need two copies of the altered gene in order to get hemophilia. If they only have one copy, then they are a carrier.