you must design a valid experiment to show that there are microorganisms in the air. what would be your dependent variable?
sterilized broth
growth of organisms in the broth
exposure to microorganisms in the air
you must design a valid experiment to show that there are microorganisms in the air. what would be your control group?
open flask with unsterilized broth
open flask with sterilized broth
sealed flask with unsterilized broth
sealed flask with sterilized broth

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.

Select all that apply genes are specific nucleotide sequences occur in numbers that are the same as the number of chromosomes are located in a specific place on a chromosome determine the traits of an organism are units of rna

Which of the following words best matches this definition: the process in which the best adapted organisms survive and pass on their traits, while those that are not well adapted do not survive to pass on their traits. question 3 options: acquired selection natural selection artificial selection organic selection