Five students get sick with a cold after a weekend field trip to the aquarium with their classmates. Which best explains why these students became sick? A contact with an infected fish

B. contact with an infected person

C. contact with contaminated food

D contact with a contaminated water

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.

Sarah and john are having a discussion on genetic diversity. sarah believes that it happen over a long period of time. john it happens immediately. who is correct? a. sarah is correct because genetic diversity occurs over a long period of time. b. john is correct because genetic diversity occurs immediately. c. both are correct because genetic variation can occur or long period of time. d. neither are correct because genetic diversity occurs over any period of time

Which of the following is a common response to cell signaling?