It is well known that biological changes at the molecular level have

Question

It is well known that biological changes at the molecular level have morphogenetic consequences, consequences affecting the formation and differentiation of tissues and organs. It is superfluous to point out that gene mutations and disturbances of the bio-synthetic processes in the embryo may result in abnormalities in the morphology (structure) of an organism. However, whereas much is known about causes and consequences at the molecular level, and in spite of an enormous accumulation of chemical and morphological data on embryos of various kinds, our understanding of how genes control morphogenesis is still far from complete. Perhaps one reason for this is that molecular biologists and morphologists speak different languages. Whereas the former speak about messenger-RNA and conformational changes of protein molecules, the latter speak of ectoderms, hypoblasts, and neural crests.

One solution to this predicament is to try to find some phenomena relevant to morphogenesis which both the molecular biologist and the morphologist can understand and discuss. As morphogenesis must be basically the result of changes in behavior of the individual cells, it seems logical to ask morphologists to describe the morphogenetic events observed in terms of changes in cellular contact, changes in the rate of proliferation of cells, or similar phenomena. Once this is done, it may be appropriate to ask questions about the molecular background for these changes. One may, for instance, ask whether variations in cell contact reflect alterations in the populations of molecules at the cell surface, or one may inquire about the molecular basis for the increased cell mobility involved in cell dispersion.

Studies of this kind have been carried out with cells released from tissues in various ways and then allowed to reveal their behavior after being spread out into a thin layer. In many cases, such cells show the ability to reaggregate, after which different cell types may sort themselves out into different layers and even take part in still more intricate morphogenetic events. But in most cases, the behavior of cells in the intact embryo is difficult to study because of the thickness and opacity of the cell masses. The sea urchin embryo, however, has the advantage that it is so transparent that each cell can be easily observed throughout development. Thus, by recording the development of a sea urchin embryo with time-lapse photography, the research scientist might discover previously unknown features of cellular behavior. Perhaps the study of the sea urchin in this manner can provide a medium by which the molecular biologist and the morphologist can begin communicating with each other more effectively about the way in which genes control morphogenesis.   1 
 1. The author’s primary purpose is to

(A) outline a procedure and discuss possible applications
(B) evaluate an experiment in terms of its applicability to medical research
(C) propose a method for curing specific genetic disorders
(D) explain a problem and suggest a solution for it
(E) reveal the shortcomings of several attitudes toward genetic research

2 
 2. The author states that research into the genetic control of morphogenesis has been impeded by

(A) an incomplete understanding of biomolecular reactions that are highly complex
(B) a lack of communication between scientists whose work could be complementary
(C) a reluctance on the part of morphologists to share data with molecular biologists
(D) a lack of research in the area of morphology
(E) the unavailability of suitable research equipment

3 
 3. The major objective of the author’s proposal is to

(A) devise a technique for proving that abnormalities in morphology result from gene mutations
(B) improve the procedures for organizing chemical and morphological data
(C) increase the accuracy of measurements of cell populations and cell mobility
(D) reduce the margin of error in the study of conformational changes of protein molecules
(E) provide a plan for increasing knowledge about the influence of genes on morphogenesis

4 
 4. It can be inferred from the passage that some cells that have been isolated from an organism have the ability to

(A) control morphogenesis
(B) reform to make higher organisms
(C) reorganize to form clusters of cells
(D) regulate the transmission of light through the cell wall
(E) regulate the rate of tissue formation

5 
 5. It can be inferred from the passage that the study of the effects of genes on morphogenesis is best accomplished by observing

(A) intact developing embryos
(B) adult sea urchins
(C) isolated living cells
(D) groups of genetically mutated cells
(E) cells from the same kink of tissue

6 
 6. According to the passage, it is difficult to study cells in most intact embryos because

(A) morphogenetic events cannot be isolated
(B) embryos die quickly
(C) embryos are difficult to obtain
(D) individual cells reaggregate too quickly
(E) individual cells are difficult to see

7 
 7. Which of the following sequences best describes the author’s suggestion for future research on morphogenesis?

(A) Accumulation of data, simplification of language, explanation of morphogenesis
(B) Dispersion of cells, evaluation of cell activity, development of an explanatory hypothesis
(C) Classification of cell types, separation of cell, observation of cell activity
(D) Observation of cell development, description of cell behavior, explanation at the molecular level
(E) Differentiation of cell types, description of cell structure, analysis of molecular components

8 
 8. The tone of the author’s discussion of the difference in the language used by morphologists and that used by molecular biologists is one of

(A) indifference
(B) neutrality
(C) derision
(D) approbation
(E) indignation

RC Butler 2021  -  Practice Two RC Questions Everyday.   
Passage # 81 Date: 26-Feb-2021
 This question is a part of RC Butler 2021 .  Click here for Details

MBAB123 · Answer

14 minutes, got 6/8 correct. (Got Q5 and Q7 wrong)

Q5 has the perfect trap answer for when you're deep into your practice and not at your sharpest. Options B very conveniently mentions "adult" sea urchins. I got picked that answer without a second thought.

Sajjad1994 
can you please post the explanation for Q7. I went for B as the last passage seems to start with dispersion of cells and then observing their activity. I wasn't really sure about this one so would like to see the OA.

weirdcoffeeperson · Answer

Got all correct in 9:42.
Though a pre-read intimidated me at first, I found the questions to be really easy and option elimination a breeze.

Pankaj0901 · Answer

That's nice weirdcoffeeperson . Any tips you may give please? I struggle with RC's (I got 3/8 in 18 minutes)- It's been 3 months I have been reading a lot and practicing 3-4 RC's every day, and now I have started to lose confidence and I feel like giving up. Maybe GMAT isn't for me.

kntombat · Answer

Sajjad1994 , can you share the Official Explanation for question 8 as and when possible? Thank you. Pankaj0901 , You can refer to this article : https://blog.targettestprep.com/gmat-re ... sion-tips/ .

Harsh9676 · Answer

Hey Just don't give up. I had been in your shoes, just trust yourself and practice. The trick here is that Read Slow (initially), Don't panic & try to understand, be very critical about every answer choice (I mean you need to verify every word in Answer choice). GMAT Club has a ton of passages. Use this link and go from Medium to Hard in each type of RC. Also RC is just a skill you can develop and any new skill can be learnt in 21 days apparently. However, don't go about solving 10-12 passages a day. Solve one passage from each type and may be try to answer a few queries that people ask in the forum about the passage. https://gmatclub.com/forum/reading-comp ... 29341.html Hope this helps Harsh

mmleao · Answer

Regarding Q5, the passage says "But in most cases,  the behavior of cells in the intact embryo is difficult to study  because of the thickness and opacity of the cell masses."

The exception is the sea urchin embryo, ok. But option A refers to  any  "intact developing embryo", not the sea urchin specifically, thus I eliminated this option.

Doesn't it make any sense?

Thank you all!

Akarshkhan86 · Answer

Hello  Sajjad1994

Can you share the OE for Question 7 please?

VerbalBot · Answer

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It is well known that biological changes at the molecular level have

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It is well known that biological changes at the molecular level have

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