What did chargaff discover while studying bases in the dna of organisms?
the bases in the dna of each organism were unique.
the ratios of thymine and adenine were similar, as were the ratios of guanine and cytosine.
the overall percentages of bases were different from one organism to the next.
there were equal amounts of all four bases in every organism, or 25 percent of each base.

Next pretest: evolution select the correct answer in a laboratory population of flies, the female flies are gray and the males are yellowish gray. biologists observed that all the male flies had an equal chance for reproduction, but the male flies with the brightest colors were more likely to successfully reproduce. what phenomenon could explain such a change? a sexual selection b. disruptive selection c. stabilizing selection d. directional selection

(drag each tile to the correct location.) categorize each term as something that is typical of a scientific theory, a scientific hypothesis, or both. - a tentative statement used to guide scientific investigations. - makes predictions about future events. - can be tested by many independent researchers. - based on observations of natural phenomena. - a well-established, highly reliable explanation.

Melting glaciers is a serious threat to the environment what is the possible consequence of melting glaciers on polar bears?