May 1, 2011
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Pre-Medical
Confused about these two questions, if someone could please help me out with the explanations, I would appreciate it!

PS 25 - I don't understand why C couldn't also be correct

BS 47 - Why is the correct answer correct? I felt like trimming a few nose hairs wouldn't have as much of an effect.
 

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salim271

Patience is tough. :/
May 21, 2011
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I think for the PS one, C might kind of be correct but B is the better answer. As for the BS one, nose hairs capture particulates when smoke is inhaled in the nasal passage so less gets into the lungs. They dont do a lot, but they do more than sensory cells, which basically tell you you're inhaling smoke. If you smoke, it doesnt matter whether or not you can tell you're smoking, you're still going to get cancer. Sensory cells do absolutely nothing to prevent cancer.
 

muhali3

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May 6, 2009
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BS47. The passage said to filter out microbes, the body first uses nasal hair, then cilia, then macrophages. It said nothing about sensory cells in the nose, and damage to sensory cells wouldn't change susceptibility to infection.

PS25. I got this wrong too. But air resistance is more influenced by velocity than surface area. The passage didn't really say anything about that though. http://upload.wikimedia.org/math/2/8/5/28560fb9ccae7b5f811de11f965d5478.png
 
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May 1, 2011
177
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Pre-Medical
BS47. The passage said to filter out microbes, the body first uses nasal hair, then cilia, then macrophages. It said nothing about sensory cells in the nose, and damage to sensory cells wouldn't change susceptibility to infection.

PS25. I got this wrong too. But air resistance is more influenced by velocity than surface area. The passage didn't really say anything about that though. http://upload.wikimedia.org/math/2/8/5/28560fb9ccae7b5f811de11f965d5478.png
okay, i understand the bio. one now! i shouldn't have made the leap to thinking about cells when it wasn't even discussed...

ps i understand after looking at that equation but seriously!?!
 

paul411

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May 27, 2010
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I missed that question #25 on PS as well. I guess the takeaway here is to pay attention to "compact object falls a very short distance". It cannot pick up significant velocity in that "very short distance" for the surface area to have enough of an impact.

Yeah, I thought it was a ridiculous question too. Also, I don't think EK covered that air resistance formula.
 

indianjatt

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Sep 23, 2009
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Can we not rule out "area is negligible" for the PS question right away? I mean the question is asking why can we ignore air resistance at smaller distances. It's not that the area is negligible.... if that was the case then at higher altitudes the area would also be negligible (area wouldn't change) and we would have no difference in air resistance, but we know that we do. So that obviously can't be the reason, but rather due to the velocity.
 
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