The lives of plants include two generations that alternate.

Scientist have long study the earths climate by looking at which of the following? the earths orbit. the earths rock layers. the antarctic ice. the earths oceans.

Based on the observation that only male crickets produce a song, you hypothesize that a male's song is a form of communication to potential mates. you set up a simple experiment to test this hypothesis. in the laboratory, you place a male snowy tree cricket in enclosure a, which is adjacent to enclosureb. in enclosure b, you place other insects, one at a time, and observe their responses to the male's song. the enclosures are designed so that the two insects being tested cannot see or smell each other, but sound is transmitted from enclosure a to enclosureb.

What blood vessels carry blood to the heart? away from the heart?