Jamal is testing muscle strength in frogs. He thinks that their muscle strength will increase if more protein is added to the frogs’ diet. To test this, he increases the protein in twenty frogs’ diet. He leaves the other twenty frogs’ diet as is. Jamal then places the frogs on a line and measures the distance they can jump. He performs the experiment every day at the same time using the same measuring stick.
What represents the control group?

A)the frogs that did not get the extra protein
B)the frogs that got the added protein
C)Jamal’s use of the same measuring stick
D)Jamal’s use of twenty frogs in each group

What was the land like over 500 million years ago? what was under the sea?

Mike has a problem with his testosterone. he is unable to produce enough. which will most likely be affected by his inability to produce testosterone? check all that apply.

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.