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Retina - Conclusion problem -- pls help

Expert replies
by praveen_gmat » Wed Nov 02, 2011 11:00 am
Light is registered in the retina when photons hit molecules of the pigment rhodopsin and change the molecules'
shape. Even when they have not been struck by photons of light, rhodopsin molecules sometimes change shape
because of normal molecular motion, thereby introducing error into the visual system. The amount of this molecular
motion is directly proportional to the temperature of the retina. Which one of the following conclusions is most
strongly supported by the information above?

A. The temperature of an animal's retina depends on the amount of light the retina is absorbing.
B. The visual systems of animals whose body temperature matches that of their surroundings are more error-prone
in hot surroundings than in cold ones.
C. As the temperature of the retina rises, rhodopsin molecules react more slowly to being struck by photons.
D. Rhodopsin molecules are more sensitive to photons in animals whose retinas have large surface areas than in
animals whose retinas have small surface areas.
E. Molecules of rhodopsin are the only pigment molecules that occur naturally in the retina.

The Official Answer is B. I eliminated A,B and D because of reference to Animals. Is this way of elimination wrong? Every word must be justified and outside information cannot be used. How can the answer be B.

Experts, Tutors, please help !
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Source: — Critical Reasoning |

by CappyAA » Wed Nov 02, 2011 12:13 pm
You can't eliminate an answer because it says an animal's retina. You can assume that any retina is on an animal.

Looking at the premises, we are told that light is registered in the retina when photons change these specific molecules' shape. We're also told that sometimes there are errors in the visual system when the molecules change shape due to normal molecular motion. Finally, we're told that this molecular motion is directly proportional to the temperature of the retina. So from this, we should look for a conclusion that says that there are more errors made when the retinas are at higher temperatures.

B says this well. It says that animals that have higher body temperatures tend to have more error-prone visual systems. We can defend every word in this answer choice.
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by vaibhavgupta » Wed Nov 02, 2011 2:32 pm
praveen_gmat wrote:Light is registered in the retina when photons hit molecules of the pigment rhodopsin and change the molecules'
shape. Even when they have not been struck by photons of light, rhodopsin molecules sometimes change shape
because of normal molecular motion, thereby introducing error into the visual system. The amount of this molecular
motion is directly proportional to the temperature of the retina. Which one of the following conclusions is most
strongly supported by the information above?

A. The temperature of an animal's retina depends on the amount of light the retina is absorbing.
B. The visual systems of animals whose body temperature matches that of their surroundings are more error-prone
in hot surroundings than in cold ones.
C. As the temperature of the retina rises, rhodopsin molecules react more slowly to being struck by photons.
D. Rhodopsin molecules are more sensitive to photons in animals whose retinas have large surface areas than in
animals whose retinas have small surface areas.
E. Molecules of rhodopsin are the only pigment molecules that occur naturally in the retina.

The Official Answer is B. I eliminated A,B and D because of reference to Animals. Is this way of elimination wrong? Every word must be justified and outside information cannot be used. How can the answer be B.

Experts, Tutors, please help !
Went for B, thanks to The amount of this molecular
motion is directly proportional to the temperature of the retina
meaning higher temperature= more error. :)
If OA is A, IMO B
If OA is B, IMO C
If OA is C, IMO D
If OA is D, IMO E
If OA is E, IMO A

FML!! :/
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