In studying a species of fish, a structure is discovered that has no apparent function. If this is a vestigial structure, what should be found in some relatives of this fish?
A) The structure should be absent.
B) A similar structure should be present, but it would be larger and have a function.
C) The structure should look different and also have no function.
D) The structure should be absent from fossils of ancestors of this species.
B
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A pharyngeal specimen is inoculated on cystine-tellurite blood agar, modified Tinsdale agar, and MacConkey agar. After 48 hours of incubation, black colonies with a brown halo are observed on the Tinsdale agar and gray colonies are isolated from the cystine-tellurite agar. However, no growth is observed on the MacConkey agar. Which one of the following statements explains this discrepancy?
a. The MacConkey agar is most likely ex-pired. b. The MacConkey agar should be incubated an additional 24 hours to observe growth. c. The pH of the media may be altered, causing an environment that is too acidic for the organism to grow. d. No discrepancy is present; this organism does not grow on MacConkey agar.
Which of the following statements relate to natural selection?
A) Populations experience differential reproductive success. B) Breeding is done intentionally with the intent to increase the frequency of desired traits. C) Variation within a population is heritable. D) Populations experience competition for resources. E) The variations in a population make no difference in terms of reproductive success.
In a certain variety of plants, a cross between a red-flowered plant and a white-flowered plant
produced an all-red flower F1. In the F2 there were 140 red-flowered plants, 50 cream-flowered plants, and 65 white-flowered plants. (a) Offer an explanation for this F2 ratio. (b) What ratio would be produced in a testcross of the F1 hybrid? (c) What ratio would be produced if all the white-flowered F2 plants were crossed among themselves? What will be an ideal response?
Darwin spent five years doing research while sailing aboard the
a. H.M.S. Pinafore. b. H.M.S. Beagle. c. H.M.S. Hood. d. H.M.S. Constitution.
e. H.M.S. Howe.