25%

50%

75%

100%

Men have only one X chromosome so they cannot be heterozygous carriers.

Woman have only one X chromosome so they are less likely to have an linked allele.

Men have only one X chromosome so they are less likely to have an linked allele.

Women only receive X chromosomes from their mother.

Homozygous dominant (TT)

Heterozygous (Tt)

Homozygous recessive (tt)

1

2

3

4

XX

XY

YY

X^CX^C and X^cY

X^CX^c and X^CY

X^cX^c and X^cY

It is halved.

It is doubled.

It stays the same.

It is halved.

It doubles.

It is quadrupled.

It stays the same.

The allele for red eyes in fruit flies is dominant over brown eyes.

The allele for red eyes in fruit flies is recessive to brown eyes.

The allele for red eyes in fruit flies is codominant with the brown-eyed allele.

The allele for red eyes in fruit flies is a multiple allele with the brown-eyed allele and others.

23

46

24

17

75% dominant, 25% recessive

50% dominant, 50% recessive

100% dominant

0% dominant