Why do birth control pills contain progesterone? a) progesterone controls the release of eggs. b) progesterone kills sperm cells. c) sperm are made of progesterone d) women normally have no progesterone in their bodies.

Flock x flock y flock z total pieces of food eaten (from previous page) 147 93 60 food percentage* % % % simulated number of birds in flock for 3rd generation** * divide each flock's total pieces of food by 300, the total number of pieces of food eaten. ** multiply the food percentage for each flock by the total number of birds (30).

In which situations is the principle of cross-cutting relationship useful in determining relative age?

Give an example of a trait that is controlled by more than one gene.