Can someone explain this answer?

[Temperature101]

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Humans can survive for sustained periods of time in temperatures above body temperature (37 °C). The body is able to deal with these higher temperatures by releasing sweat, which, upon evaporation, releases heat energy from the skin. Which of the following would prevent human survival only if the ambient temperature is near or above 37 °C?

A.The relative humidity of the air reaches 100%

B. Dehydration

C. Lack of access to a breeze or other air current

D. Inability to perspire

Answer: A

 

[NuttyEngDude]

If the relative humidity of the air reaches 100% then evaporation could not occur which could not release heat energy from the skin. 100% relative humidity means the air is already holding as much moisture as possible. This is the most direct answer.

Dehydration would eventually lead to no perspiration but it is not the most direct answer.

Lack of access to a breeze or other air current. Having a breeze or current would aid in evaporation but is not necessary for it to occur.

Inability to perspire would not prevent evaporation if there is liquid on the skin. This is the closest to being the correct answer but leaves alternatives. The point is that evaporation is the survival method. Evaporation could still occur this way, so long as there is liquid on the skin.

 

[MedPR]

Humans can survive for sustained periods of time in temperatures above body temperature (37 °C). The body is able to deal with these higher temperatures by releasing sweat, which, upon evaporation, releases heat energy from the skin. Which of the following would prevent human survival only if the ambient temperature is near or above 37 °C?

A.The relative humidity of the air reaches 100%

B. Dehydration

C. Lack of access to a breeze or other air current

D. Inability to perspire

Answer: A

B, C, and D would make it more difficult to release heat. A would prevent it completely.

 

[gettheleadout]

You're all wrong lol C wouldn't prevent human survival at all, B and D would prevent it regardless of temperature. Only A prevents survival ONLY in ambient temperature in excess of body temp. Reading in to evaporation vs dripping doesn't matter.


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[cheesier]

lol I am hoping they don't have questions this ridiculous on the real thing. So the reason it isn't D is because theoretically the person could be getting hosed down or splashing water on himself to cool down instead of sweating? Maybe if there is 100% humidity they're getting a cold saline drip

 

[NuttyEngDude]

Oops yeah sorry if I wasnt clear, I am saying the answer is A not D. I think it's a very tricky question and yeah the question is asking which would prevent human survival. No matter what, if the air contains the maximum amount of moisture, evaporation could not occur. It all focuses on evaporation which is why A is the answer and the others are wrong.

 

[cheesier]

I get that, but if the answer isn't D, we're assuming that the person gets moisture on their skin without sweating. That means they're getting water sprayed on them or it's raining, etc, basically, there is some contingency that makes the answer wrong. I'm saying that if they're going to introduce backstories to the answer choices, you could do the same with A and say that it isn't really true either because the person could be getting a cold saline injection that cools down their body temp even if the relative humidity is 100%. Basically a wtf question. I'm just hoping that we don't see anything like it on the real thing.

OP, where is the question from?

 

[NuttyEngDude]

hmmm ok yeah, I see what you're saying.

 

[gettheleadout]

I get that, but if the answer isn't D, we're assuming that the person gets moisture on their skin without sweating. That means they're getting water sprayed on them or it's raining, etc, basically, there is some contingency that makes the answer wrong. I'm saying that if they're going to introduce backstories to the answer choices, you could do the same with A and say that it isn't really true either because the person could be getting a cold saline injection that cools down their body temp even if the relative humidity is 100%. Basically a wtf question. I'm just hoping that we don't see anything like it on the real thing.

OP, where is the question from?

Why assume the person gets moisture on their skin without sweating?

The reason D is wrong is because the inability to perspire will prevent human survival in ALL conditions, not just when ambient temperature is above 37 C.

Hell guys the answer is right here: mcatquestion.com

Question:Humans can survive for sustained periods of time in temperatures above body temperature (37 °C). The body is able to deal with these higher temperatures by releasing sweat, which, upon evaporation, releases heat energy from the skin. Which of the following would prevent human survival only if the ambient temperature is near or above 37 °C?

Explanation: Perspiration, hydration, and air currents are all important for thermoregulation when evaporation will assist in cooling. Losing any of these could be problematic even if the ambient temperature is below body temperature since the body generates heat and its inability to release it could cause hyperthermia. However, when sweat ceases to evaporate (relative humidity of 100%), it will no longer take energy with it to cool the skin. This is a potentially lethal situation only if the ambient temperature is at or above body temperature since the body would not be able to give up heat to the environment to cool itself. A relative humidity of 100% with an ambient temperature below body temperature would not necessarily be dangerous since the body can still release heat to the environment when the environment is colder than the body. Therefore the answer is (A) since it would be problematic only if the ambient temperature is above body temperature.

 

[cheesier]

Why assume the person gets moisture on their skin without sweating?

The reason D is wrong is because the inability to perspire will prevent human survival in ALL conditions, not just when ambient temperature is above 37 C.

Hell guys the answer is right here: mcatquestion.com

Hmm, is it true that if you can't sweat and the ambient temperature is low you'll die? I would assume that it is bad for you, but why would it kill you if your body temp doesn't need to be lowered? And if in fact it does kill you regardless of temperature, the question requires you to know that anhidrosis (had to google it, lol) is deadly in all cases, which is definitely not mcat level knowledge. And if anhidrosis is only deadly above 37 C, then answer D is correct as well.

 

[NuttyEngDude]

This question is interesting, lol. Fair enough.

 

[Jepstein30]

Yea the trick here is in the ONLY.

If this was on the MCAT though, I think they would capitalize ONLY because, well, that's what test makers do when they create such questions.

 

[MedPR]

You're all wrong lol C wouldn't prevent human survival at all, B and D would prevent it regardless of temperature. Only A prevents survival ONLY in ambient temperature in excess of body temp. Reading in to evaporation vs dripping doesn't matter.


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C makes ambient temperature higher.

 

[gettheleadout]

C makes ambient temperature higher.

So what? If you can still sweat you'll be fine.


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[Temperature101]

I get that, but if the answer isn't D, we're assuming that the person gets moisture on their skin without sweating. That means they're getting water sprayed on them or it's raining, etc, basically, there is some contingency that makes the answer wrong. I'm saying that if they're going to introduce backstories to the answer choices, you could do the same with A and say that it isn't really true either because the person could be getting a cold saline injection that cools down their body temp even if the relative humidity is 100%. Basically a wtf question. I'm just hoping that we don't see anything like it on the real thing.

OP, where is the question from?

www. mcatquestion.com

 

[Temperature101]

The funny part is that I did not even consider A as an answer...D just jumped out to me and I was shocked when they said it was incorrect. I thought the inability to perspire was more extreme than having the air humidity at 100%. Now, after looking at it more closely , I think A makes perfect sense. Regardless,that was a gotcha question.

 

[MedPR]

So what? If you can still sweat you'll be fine.


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The hotter ambient gets, the harder the body has to work to maintain homeostasis. My original point was that all three of the incorrect answers increase difficulty, but do not completely prevent, of keeping body temp 37.