LR Question 19 Explanation, by LSATHacks
QUESTION TEXT: Light is registered in the retina when photons hit…
QUESTION TYPE: Most Strongly Supported
FACTS:
- Rhodopsin molecules register light by changing shape.
- Rhoposin sometimes changes shape because of molecular motion even when they are not struck by light.
- The warmer the retinas the more motion there is.
ANALYSIS: We can reasonably conclude that there is more error when the retina is warmer.
___________
- We have no clue what determines retina temperature. It isn’t mentioned.
- CORRECT. This is hard to understand. Humans are an animal with a body temperature that does not match our surroundings. We always stay around 98.6 degrees.
Reptiles tend to match their surroundings. So if it is warm then they get warm. And presumably their retinas get warm. This causes more molecular motion and therefore causes the Rhoposin to get errors.
So animals that shift their body temperature to match their surroundings will have more errors when it is warm because their retinas warm up. When it is cold their retinas cool and they have fewer errors. - We only know that their error rate from molecular motion increases. But Rhodopsin still might be just as fast at dealing with light from photons.
- We have no idea. The stimulus doesn’t even mention surface area. More light might get in but presumably the animals have more Rhodopsin as well.
- There might be more. We aren’t told if Rhodopsin is alone or if there are other pigments.
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Hey, I don’t get how come you concluded that “The warmer the retinas the more motion there is” from motion being “directly proportional to the temperature of the retina”? How do you know proportional is warm…why not colder?
Because temperature goes up. Higher temperature = warmer.
But could it not have been inversely proportional? As in the hotter it gets the more error prone in the visual system? Or are we to assume that all proportional relationships are positively related unless explicitly stated otherwise?
On the LSAT (and elsewhere) you can assume that all directly proportional relationships imply that an increase in one factor in the relationship results in a proportional increase in the other.
If these factors were negatively correlated, then the stimulus would specify that it was an inversely proportional relationship.