PrepTest 128, Section 3, Question 13
Sexual reproduction is achieved when the gamete of(76 more words not shown)
Which one of the following(12 more words not shown)
- AAll female organisms(5 more words not shown)
- BOnly female organisms(6 more words not shown)
- CGenetic material is(12 more words not shown)
- DThe role of(16 more words not shown)
- EIt is likely(17 more words not shown)
Reading the argument
Keep the two parts of the cell separate. In the nucleus, the male and female gametes contribute equal amounts of genetic material. In the cytoplasm, which is outside the nucleus, the genetic material comes exclusively from the female's gamete.
Now place GM62. We're told it is found only in cytoplasm. Since the genetic material there comes only from the female gamete, any GM62 contributed to the offspring must come from that source too.
What we’re looking for
The question asks what follows from the passage. We don't need to add a premise to prove an author's argument; we need to connect the facts already given. My prediction is about the source of GM62: if it is contributed, only the female organism can contribute it.
Working the answers
- A
We don't know that every female organism has GM62 to contribute. Perhaps some species, such as cats, don't have it at all. That's a hypothetical possibility, not a biological claim. The passage tells us where GM62 comes from when it is contributed; it doesn't guarantee that every offspring receives it.
- BCorrect
GM62 is restricted to cytoplasm, and the genetic material in the new cell's cytoplasm comes exclusively from the female gamete. Therefore, only female organisms can contribute GM62 to their offspring. “Only female” identifies the possible source without asserting that every female contributes it.
- C
The equal division concerns the male and female contributions within the nucleus. It doesn't compare the total genetic material in the nucleus with the total in the cytoplasm. Those compartments could contain very different amounts, and the stated equal contribution to the nucleus would still hold.
- D
A contribution of additional genetic material doesn't automatically establish greater importance. We aren't given a rule equating amount with importance, nor a full account of everything each gamete contributes. D adds an evaluation that the passage never makes.
- E
The passage doesn't predict future discoveries. Learning that one type of material comes exclusively from the female gamete doesn't establish that researchers will probably find a different type contributed exclusively by the male gamete.
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