| A | B |
|---|
| 23 | number of pairs of human chromosomes |
| XY | male combination |
| XX | female combination |
| carrier | person who has recessive gene that doesn't show |
| sex-linked traits | carried onthe sex chromosomes |
| gender | determined by father |
| boys | inherit sex-linked traits more frequently |
| mothers | pass sex-linked traits to sons |
| multiple alleles | traits controlled by more than one pair of genes |
| hemophilia | blood lacks clotting factor |
| colorblindness | eyes lack cones to see colors |
