During meselson and stahl’s experiment, e. coli was grown on heavy nitrogen for what purpose?
a. so each generation of dna would have a different weight to distinguish them by.
b. so each generation of protein would have a different weight to distinguish them by.
c. to determine how the bacteria functioned with a heavier element.
d. to see how the heavy nitrogen affected their dna.

Agroup of students are walking in the park, and one of them takes a picture of a pollen grain that is being blown by the wind.what caption can the student use for this picture? fahrte "littl1111111nimmt-hhhfull film# # #gene mutation in actiongene flow at workgenetic drift as it happensnatural selection in progresshii

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.

Astudent completed a lab report. which correctly describes the difference between the “question” and “hypothesis” sections of her report? “question” states what she is asking, and “hypothesis” states the result of her experiment. “question” states what she is asking, and “hypothesis” states what she thinks the answer to that question is in “if . . then . . because” format. “question” describes what she is trying to find out, and "hypothesis" states the procedures and methods of data collection. “question” describes what she is trying to find out, and “hypothesis” states any additional information or prior knowledge about the question.