The graph depicts four possible patterns for the abundance of 3TC-resistant HIV within an infected human over time. If 3TC resistance is costly for HIV, then which plot (I—IV) best represents the response of a strain of 3TC-resistant HIV over time, if 3TC administration begins at the time indicated by the arrow?

#Question id: 4651

#Section 2: Evolution

Some members of a photosynthetic plant species are genetically resistant to an herbicide, while other members of the same species are not resistant to the herbicide. Which combination of events should cause the most effective replacement of the non-herbicide-resistant strain of plants by the resistant strain?

1. The presence of the herbicide in the environment

2. The absence of the herbicide from the environment

3. The maintenance of the proper conditions for one generation

4. The maintenance of the proper conditions for many generations

#Question id: 4655

#Section 2: Evolution

Over evolutionary time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses?

#Question id: 4656

#Section 2: Evolution

Logically, which of these should cast the most doubt on the relationships depicted by an evolutionary tree?

#Question id: 4657

#Section 2: Evolution

 Which of the following statements most detracts from the claim that the human appendix is a completely vestigial organ?

#Question id: 4658

#Section 2: Evolution

Members of two different species possess a similar-looking structure that they use in a similar fashion to perform the same function. Which information would best help distinguish between an explanation based on homology versus one based on convergent evolution?

#Question id: 4698

#Section 2: Evolution

It has been observed that organisms on islands are different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence that