heterogametic sex

homogametic sex

hemizygosity

nondisjunction

2. Although mammals and fruit flies use XY determination, the mechanisms are different. What determines "maleness" in these two groups?

3. Explain how reciprocal crosses can be used to infer that a trait is influenced by a sex-linked gene.

4. How did Bridges' study of eye color in fruit flies help establish that genes are on chromosomes?