The accompanying relative frequency histogram shows the number of hours of sleep (sleep hours) reported as experienced "last night" for 27 college men. complete parts (a) and (b) below.

The number of living organisms in a particular area is

What are genotypes? what are phenotypes?

Which member of the following food chain will be least affected by ddt, a pesticide water pollutant, if bio-magnification is occurring? algae> zooplankton> crayfish> leopard frog> large mouth bass