Sex-Linked Traits
Chapter 4.1
Answers to Questions
1. What are sex-linked traits?
- Human traits that are carried on the sex
chromosomes.
2. What’s a carrier?
- A person who has one recessive allele for a trait and
one dominant allele.
3. Males have one X chromosome. Males will be colorblind if they have one allele, and females need two
recessive alleles to be colorblind.
Sex-determination

Autosomes --- Non-sex chromosomes; 22
pairs or 44 individual chromosomes.

23rd pair --- Sex chromosomes; determines
gender. XX --- female XY --- male
Sex-influenced Traits

Expressed differently in both sexes due to
different hormones which are determined by
different sets of genes.

Examples --- male-pattern baldness, horn size
in mountain sheep, and feather color in
peacocks.
Sex-linked Traits



Traits found on sex chromosomes.
2 traits that are X-linked inheritance in
humans are certain forms of color-blindness
& hemophilia.
Hemophilia --- blood disorder where your
blood doesn’t clot.