Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Different types of sex chromosomes. (A) In XY systems males are the heterogametic sex and in ZW systems females are the heterogametic sex. (B) Proportion of time each chromosome spends in males. Male proportions are blue and female proportions are red.
