The number of trout in a lake drops when the lake is polluted. the trout population later increases, but the allele frequencies are different. what does this situation represent? a. genetic drift b. artificial selection c. speciation d. biodiversity

Blood has traveled from the heart to the toes. which describes the next step of the circulation process?

The fruit of a certain plant is sweet and fleshy. the seeds of this plant have a seed coat that is fairly tough. the seeds germinate better if they are exposed to acid, or scarification. what is the most likely type of dispersal for this seed? water animal wind

Which of these substances does not protect against invaders in the nonspecific immune response? a. saliva b. mucus c. tears d. urine