Cold air falls because a. its's icy
b. it's more dense than warm air
c. it's heavier than warm air
d. It's less dense tha warm air

Mention true or false : a) cholera is marked by acute diarrhea and no urination. b)mosquitoes are the source of dysentery germs.

Apopulation of black bears depends on salmon from a stream for food. if a drought causes the stream to run dry one year, how will this likely impact the black bear population?

Why did mendel use pea plants in his experiments? a. they have no alleles. b. they are haploid organisms. c. they reproduce quickly. d. they are all male.