Understanding Chromosomes and X-linked Inheritance

How many pairs of chromosomes do human beings have in their cells?

• 24 pairs

• 22 pairs

• 21 pairs

• 23 pairs

Why are boys more affected by alterations in genes on the X chromosome?

• They inherit more genes from their father

• They have a stronger Y chromosome

• They lack a second X chromosome with a healthy backup

• They have two X chromosomes

What is the chance of a carrier mother having a son affected by an X-linked disorder?

• 1 in 3

• 1 in 4

• 1 in 2

• 1 in 5

Which of the following is an example of an X-linked inherited disorder?

• Color blindness

• Down syndrome

• Cystic fibrosis

• Sickle cell anemia

What happens to all daughters of a man affected by an X-linked disorder?

• They will inherit the Y chromosome

• They will be affected

• They will be carriers

• They will be unaffected