If you're interested, the answer is B: the bones of birds are extremely light. Heavy bones would make flight much more difficult for birds.
“I, II, and III” Questions
“I, II, and III” questions are multiple-choice questions that provide you with three possible answers, and the five answer choices list different combinations of those three.
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A population of animals is split in two by the formation of a river through their territory. The two populations gain different due to the different natures of their new habitats. When the river disappears, the two populations can no longer interbreed. What has occurred? |
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I. Natural selection
II. Convergent evolution
III. Speciation
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(A) |
I only |
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(B) |
II only |
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(C) |
I and III only |
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(D) |
II and III only |
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(E) |
I, II, and III | |
There's an upside and a downside to questions like this. Suppose you know that the scenario described by this question does involve speciation, but you aren't sure about natural selection or convergent evolution. The downside is that you can't get the right answer for sure. The upside is that you can eliminate A and B and significantly increase your chance of guessing the right answer. As long as you're not afraid to guess—and you should never be afraid to guess if you've eliminated an answer—these questions shouldn't be daunting. By the way, the answer is C: changes in organisms'istics due to changes in habitat are a result of natural selection, and the inability of the members of a former population to interbreed after being separated for a long time is speciation.
