A pregnant mouse is exposed to high levels of a chemical. Many of the mice in her litter are deformed, but when they are interbred with each other, all their offspring are normal. Which two of the following statements could explain these results?
(a) In the deformed mice, somatic cells but not germ cells were mutated.
(b) The original mouse's germ cells were mutated.
(c) In the deformed mice, germ cells but not somatic cells were mutated.
(d) The toxic chemical affects development but is not mutagenic.
Choices (a) or (d) are correct. Choice (b) cannot account for these results because a mutation in the original mouse's germ cells would have no effect on the fetuses she was already carrying. Neither can choice (c), because mutations in the germ cells of the fetuses while in utero would have had no effect on their development, but they might have led to mutant mice among their offspring.
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Answer the following statement true (T) or false (F)
Over the past two centuries, how has the growth of human population changed?
A) It has leveled off slowly. B) It has increased steadily. C) It has exhibited "boom and bust" growth. D) It has increased exponentially.
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In what way could marine invertebrates that scatter gametes in the water prevent the sperm from one species from fertilizing the eggs of another species?
a. by preventing the sperm from binding to or entering the egg of another species b. by preventing the resulting hybrids from passing on their genetic material to offspring c. through behavioral isolation d. through geographic isolation e. by preventing the resulting hybrid from surviving