Sex-Linked Inheritance

How many PAIRS of chromosomes do humans have?

• 23

• 46

• 1

• 2

How many PAIRS of sex chromosomes do humans have?

• 23
• 46
• 1
• 2

Which of the following are sex chromosomes?

• X

• Pairs #1-22

• Y

Which genotype represents a male that has normal vision? (not color blind)

• X^BX^b

• X^BY

• X^bY

• X^BX^B

Which of the following genotypes is a female with normal vision? (select all that apply)

• X^BX^b

• X^BX^B

• X^bX^b

• X^BY

What was the term for a female who has normal vision but has the allele for color blindness? (X^BX^b)

Are males or females more likely to be carriers for sex-linked traits?

• Males

• Females

• Both

Why can males not be carriers for many sex-linked traits?

• Because males are more affected by diseases

• Because males only have 1 X chromosome and whatever allele it carries is what they are (they can't be heterozygous)

• Because females can overcome diseases regardless of their genes

What percentage of the female offspring will be a carrier for this recessive disease?

• 0%
• 50%
• 100%
• 25%

Vitamin D resistant rickets (deformed bone formation) is a sex-linked DOMINANT trait.  According to the Punnett square, what percentage of female offspring will have the disorder?

• 0%
• 25%
• 50%
• 100%