Crop rotation is important because:

some plants use a lot of nitrogen.
it increases soil fertility.
repeated planting of the same crops decreases soil quality.
all of the above.

Plz ! cattle ranchers and dairy farmers rarely allow all of their animals to reproduce instead they practice selective breeding and only encourage the reproduction of animals with specific features. which of the following cows would a dairy farm most likely choose to reproduce? a. a cow that makes a lot of milk. b. a cow that can run quickly. c. a cow with a think, soft fur. d. a cow with large, strong hooves.

To answer this question, researchers studied populations of the dusky salamander (desmognathus ochrophaeus) living on different mountain ranges in the southern appalachian mountains. the researchers tested the reproductive isolation of pairs of salamander populations by leaving one male and one female together and later checking the females for the presence of sperm. four mating combinations were tested for each pair of populations (a and b)—two within the same population (female a with male a and female b with male b) and two between populations (female a with male b and female b with male a). the proportion of successful matings for each mating combination was measured. for example, when all the matings of a particular combination were successful, the researchers gave it a value of 1; when none of the matings were successful, they gave it a value of 0. then the researchers calculated an index of reproductive isolation that ranged from 0 (no isolation) to 2 (full isolation). the reproductive isolation value for two populations is the sum of the proportion of successful matings of each type within populations (aa + bb) minus the sum of the proportion of successful matings of each type between populations (ab + ba). the table provides data for the geographic distances and reproductive isolation values for 27 pairs of dusky salamander populations.

What is the next step in the process after a substrate enters the active site of an enzyme