imSKR wrote:
Quote:
7. According to the passage, the morphogenetic determinants present in the unfertilized egg cell are which of the following?
(A) Proteins bound to the nucleus
(B) Histones
(C) Maternal messenger RNA's
(D) Cytoplasm
(E) Nonbeaded intervening DNA
Quote:
He and other biologists studying a wide variety of organisms have found that these particular RNA’s direct, in large part, the synthesis of histones, a class of proteins that bind to DNA.
Could not the answer be B ? I know its not. please check my thinking :
These maternal RNA are carriers that come from maternal genes that interact with histones ( present in cytoplasm ) as morphogenetic determinants . These determinants when interact with carrier RNA bind with DNA and thus move to nucleus for fertilization.
With such thinking, I was able to understand last 2 paragraphs by forming a picture in mind and when I come across these question , I thought that maternal is outside embryo cells and maternal determinants are part of embryo cells . Thus I rejected C.
I rejected A ( protein bound to DNA) and D ( location where it is present)
I rejected C and E because maternal genes and DNA are external carriers
Thus was confident with B but heart broken in the end.
Please suggest
AndrewN sir
VeritasKarishma GMATNinja . kindly correct my way of thinking ( one side I made complete picture and understood the details to an extend that helped me to crack the questions quickly but other side I was falter in Q7 in which 67% of students have chosen right answer.
Remember,
imSKR, that a question prefaced by
According to the passage is a detail question, so this is not something we should have to labor over too much. Just match keywords between the question stem and passage and choose the answer that fits. Here, we need to find
morphogenetic determinants, but we also need to keep
unfertilized egg cell and, believe it or not,
are in mind. That is, we need to know
exactly what is synonymous with
morphogenetic determinants in the passage.
Paragraph two first mentions our morphogenetic determinants, but only in a question. What follows in the paragraph hints at an answer, but we never actually get one.
Paragraph three starts by mentioning
substances that function as morphogenetic determinants and adds that they are
located in the cytoplasm of the egg cell. I draw attention to
located in because where something is found is not the same as the thing itself. Choice (D), cytoplasm, is a decent trap answer, but nothing more. Getting back to the passage, we seem to be getting closer when we reach the keywords
unfertilized egg:
In the unfertilized egg, the substances are inactive. But what are these inactive substances? Now we are really following a trail of breadcrumbs. The good news is that the rest of the paragraph discusses a
fertilized egg, so we will not find our answer there.
Paragraph four delivers the end product right away:
The substances that Gross studied are maternal messenger RNA’s—products of certain of the maternal genes.Putting it all together, we can appreciate that maternal messenger RNA's are the substances that are inactive in an unfertilized egg, that are found in the cytoplasm of the egg cell, and, most importantly, that function as morphogenetic determinants. There is no way to argue against (C). The information about histones in the final paragraph never tells us directly that histones are morphogenetic determinants. You should not have to read too deeply to get detail questions. Stick to the surface and match keywords instead. I guarantee you will perform better on RC questions and save your critical reasoning skills for tougher challenges.
I hope that helps. Thank you for drawing my attention to the question.
- Andrew
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