Light is registered in the retina when photons hit molecules

OFFICIAL EXPLANATION

The correct answer choice is (B).

Premise: Light is registered in the retina when photons hit rhodopsin molecules and the molecules change shape?
Premise: Due to normal molecular motion, rhodopsin molecules sometimes change shape without having been hit by light. This change causes errors in the visual system.
Premise: The amount of molecular motion is directly proportional to the temperature of the retina.

Answer Choice A: The stimulus does not indicate that the temperature of the retina depends on the amount of light. It could easily be affected by other factors, such as body temperature. About 15% of test takers fell prey to this answer.

Answer Choice B: This is the correct answer and just over 40% of test takers correctly choose this answer. To prove this answer, you must link together several pieces of information. First, the last sentence of the stimulus shows that the amount of rhodopsin molecular motion is directly proportional to the temperature of the retina, and the second sentence of the stimulus shows that this motion causes visual body temperature (remember, the retina is a body part) to the temperature of the surroundings and then rightly notes that hot surroundings would cause more visual errors than cold surroundings if body temperature matched those surroundings.

Answer Choice C: This was the most popular incorrect answer, and just under a quarter of test takers fell for this answer. The answer is wrong because we do not know that temperature causes the rhodopsin to react more slowly. Higher retinal temperature causes the rhodopsin molecules to change shape, but no mention is made of reaction time. This answer falls under the "New information" category.

Answer Choice D: Another New Information answer choice. Similar to answer choice (C), this answer fails the Fact Test because no information is given about the surface area of the retina. Answer choices (C) and (D) are great examples of how an answer can contain information unmentioned by the stimulus. These answers are somewhat attractive because there is nothing actively wrong about them and thus they could be true. To avoid them, always keep in mind that your goal is to find the answer that must occur based on the information in the stimulus.

Answer Choice E: While the stimulus focuses on rhodopsin, no indication is given that rhodopsin is the only naturally occurring pigment molecule-there could be others.
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The gist of the argument is
Increase in temperature -->Increase in molecular activity -->Increase in error .
A : The argument does not talk about absorption : So incorrect
B: Only option that makes sense : Hence correct .
C: No mention of rhodopsin reacting slowly or quickly to photon hits : Incorrect
D: No mention of surface areas : Incorrect
E: No mention of rhodopsin being the only pigment molecule (rhodopsin is a pigment does not mean that its molecules are the only pigmented molecules): Incorrect

These kind of questions are best solved from POE (Power of Elimination). If you go through all the choices, four of them have nothing to do with the information provided in the statement.

Incorrect . Author does not say that light absorption raises the temp of the eye. (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.

Incorrect. Not given in the premises. (C) As the temperature of the retina rises, rhodopsin molecules react more slowly to being struck by photons.

Incorrect. Nothing related to the surface area has been mentioned in the premises. (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.

Incorrect. Nothing mentioned about this (E) Molecules of rhodopsin are the only pigment
molecules that occur naturally in the retina.

We can always argue that how the hell are these animals been introduced. It is stretching it too far etc. Please note -

1. By POE, we are left with only one choice.

2. Secondly, the question is asking us to draw a conclusion based on the info in the statement. Based on the statement, it is correct to say that animals whose body temp match the surroundings will have more error in vision, in hot surroundings than in cold. True. Molecular motion is DIRECTLY PROPORTIONAL to the temp. Therefore, hotter temp will introduce more motion, therefore, more error.

Here the conclusion is the molecular motion of rhodopsin is directly proportional to the temperature of the retina.
In B the visual system of the animals is more error prone in hot temp than in cold temp. which means as the temp increases the molecular motion of rhodopsin also increases which in turn causing the visual error.

This one supports to the information provided above. So B is correct

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, rhydopsin 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.

Hi Everyone

I have a doubt a read it in the MGMAT guides that for must be true questions an answer choice that introduces new information is considered wrong.
Then why in this question the correct answer is B and not C where in the stimulus have they mentioned animals??

Can anyone please explain...

We can't really deduce C as it says that As the temperature of the retina rises, rhodopsin molecules react more slowly to being struck by photons while stem says that The amount of this molecular motion is directly proportional to the temperature of the retina. To me, I inferred this as -as temperature of the retina rises, rhodopsin molecules' motion will increase.

But at the same time B also doesn't look good either as it says that The visual systems of animals whose body temperature matches that of their surroundings are more error-prone in hot surroundings than in cold ones. The stem never mentions that temperature of the retina will be same as that of body. In a way, we might apply common sense here but not sure if we can have this common sense assumption which is never stated or rephrased in the stem. Moreover, as you mentioned the stem never says anything about animals specifically.

Would like expert inputs here!! Will be helpful

Hi guys,
Lemme try to attempt this one! I marked B though ( I agree that "animal" threw me also off)

A .The temperature of an animal's retina depends on the amount of light the retina is absorbing. -- Nowhere does it states that about the amount of light that gets absorbed. It just talks about the light photons being hit. INCORRECT

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. - Assume that a particular animal lives in hot surroundings and itself has high body temperature and therefore "high retina temperature"(retina being a part of body) too. Now, higher the temp of retina, higher the molecular motion(something that is stated in the stimulus). Vice-versa can be sad about cold temperatures. MAKES SENSE.

C) As the temperature of the retina rises, rhodopsin molecules react more slowly to being struck by photons. -- Reaction was never talked about. INCORRECT

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.--Surface areas was never talked about. INCORRECT

E) Molecules of rhodopsin are the only pigment molecules that occur naturally in the retina. --- Only pigment? No one said that ! INCORRECT

Let me know if it helped!

First of all People should stop worrying about this CR, because this CR comes under the LSAT in MGMAT.
There is a lot of structural and analytical difference between the LSAT and GMAT questions.
So please move on.

MrSobe17, notice that the question just asks us for a "strongly supported" conclusion. This will usually be a pretty solid inference, but some small uncertainty can remain. Here, we do have to know that the retina doesn't somehow stay low even as the animal's body temperature rises with its surroundings. However, since the retina is part of the animal's body, this is not a really glaring problem.

Yes, this is an LSAT question, but it's still a high-quality question, and we could see something quite a bit like this on the GMAT. Here's an example of an official GMAT question that requires us to make a bit of an assumption to reach the correct answer: although-aspirin-has-been-proven-to-eliminate-moderate-fever-45670.html
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There is no conclusion in the argument. So this is a MBT question. The correct ans choice will be the one that can be inferred from the argument.

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, rhydopsin 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?[/quote]

The mistake one can do in this question is rejecting the answer choice on the basis of word "animal" . The same I did.
But if you read closely and completely, only (B) makes sense. All others are either extreme or not supported by the passage.

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.

It's (B)
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in solving CR first thing to look out for is the conclusion . The amount of molecular motion is directly proportional to the temperature of the retina.
Analysis - more the temperature more the movement and more the disturbance in seeing .
lets' look into the option .


A) The temperature of an animal's retina depends on the amount of light the retina is absorbing.- no where it's mentioned how the temperature is linked to light.

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. - option is presented as a trap as indirect correlation is presented of temperature.
we can keep this option as it matches our analysis.

C) As the temperature of the retina rises, rhodopsin molecules react more slowly to being struck by photons. - no where its mentioned.

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? - nothing is given in argument regarding size of surface area.

E) Molecules of rhodopsin are the only pigment molecules that occur naturally in the retina.
- extreme option as only is used so it can be rejected.

hence B is the answer as it matches our analysis.

I was looking for something like: when the temperature of retina rises, the number of errors rises too - did not find this option. But B is the closest.

Breaking down the premise.
photons – hit molecules of rhodopsin – molecules change shape – light is registered
no photons are hit – but molecular motion - molecules change shape – error in vision
molecular motion directly proportional to temp of retina

Choice 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.--> So if temperature is hot outside temperature has increased. And since the body temperature matches the surroundings then temperature of retina(part of body) is likely to increase as well. Increased temperature leads to increased molecular motion as they are directly proportion, hence greater is the chance of error as visual error is caused by molecular motion. Correct Answer.
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Argument – Photons hit molecules of rhodopsin  molecules’ shape changes  light is registered by retina
Molecular shape is directly proportional to temperature. Higher the temperature  higher the motion of molecules  error into the visual system
(A) The temperature of an animal’s retina depends on the amount of light the retina is absorbing.
- The relationship mentioned in the argument is exactly opposite to that mentioned in this choice.
IF A  B, then B  A is not true unless and until it is explicitly stated.
- Wrong
(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.
- Higher the temperature  higher the motion of molecules  error into the visual system
- Note: we are making an assumption that higher motion = higher errors.
- Correct
(C) As the temperature of the retina rises, rhodopsin molecules react more slowly to being struck by photons.
- Temperature rises  molecular motion increases  thus molecules must instead react swiftly compared to reaction time in normal circumstance
- Wrong
(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.
- While “surface area” is not mentioned in the argument, IMO the reason is about “sensitive”
- Larger surface area  higher number of photons can enter  higher the number of impact on pigment  this may affect the visibility in dark.
- Sensitivity means the light registered / impact of photons will be higher in animals with larger surface areas of retina than that of any other animals. As seen in the above argument we cannot deduce anything about the sensitivity
(E) Molecules of rhodopsin are the only pigment molecules that occur naturally in the retina.
- too farfetched to be true

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.

What could be true based in above information provided in the passage?
- an inference
- an assumption
- a conclusion

All can be true but based on the structure of the passage.

Here in this passage keywords are
- light/photons
- pigment rhodopsin molecule
- molecule shape change
- normal molecular motion
- error in visual system
- proportionality of molecular motion with temperature of retina

So, molecular motion happens due to two reasons, thereby leading to error in visual system. One info of direct proportionality also plays a role - how, that is what is a mystery and possibly answer in any one of the choice that must be the right answer.

In B, molecular motion of similar degree may happen due to either light or normal molecular motion, thereby causing the error. This can be inferred, so true.

Answer B.
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