AP Biology 2020 Practice Exam 3 and Notes(Latest 2022 Review)

1. Many species of corals are threatened by the increasing temperatures and decreasing pH of ocean waters. One species, Stylophora pistillata, has been found to thrive in water that is warmer and has a lower pH than ...

1. Many species of corals are threatened by the increasing temperatures and decreasing pH of ocean waters. One species, Stylophora pistillata, has been found to thrive in water that is warmer and has a lower pH than the water that corals typically thrive in. Additionally, researchers have found that the tolerance for the new water conditions is heritable. Which of the following statements best explains the changes seen in S. pistillata in response to the changing water conditions? (A) The corals’ adaptation is an example of natural selection because the tolerance is in response to a changing environment and has a genetic basis. (B) The corals’ adaptation is an example of the founder effect because the majority of corals do not have a tolerance for warmer water. (C) The corals’ adaptation is an example of genetic drift because the change was a chance event and not the result of selection in response to environmental change. (D) The corals’ adaptation is an example of adaptive radiation because it has resulted in a wide range of species adapting to the new ocean conditions. 2. A researcher measured the temperature at which two different samples of double-stranded DNA denature (separate into single strands). Sample 1 denatured at a significantly lower temperature than sample 2 did. Based on the data, the researcher claims that the DNA in sample 2 is composed of a higher percentage of guanine and cytosine than the DNA in sample 1 is. Which of the following best supports the researcher’s claim? (A) The bonds between guanine and cytosine are covalent bonds, which require more energy to disrupt than those between adenine and thymine. (B) Guanine-cytosine pairs denature at a higher temperature because they have more hydrogen bonds between them than adenine-thymine pairs do. (C) Adenine-thymine pairs require less energy to separate because adenine and thymine are both single-ring bases. (D) Guanine-cytosine pairs require more energy to separate because one is a purine and one is a pyrimidine. GO