Aamc 10 bs#99

[Havik21]

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99) DDT would most likely initiate cancer or cause a mutation if which of the following structures is damaged?

a) Nuclear Envelope
b) Chromosome
c) Ribosome
d) Histone

Nothing in the passage supports a bridge between DDT and Genetic Material so the question can be interpreted as: Damage to which of the following causes cancer or mutations?

I went with A assuming DDT would damage the nuclear envelope and subsequently damage the DNA within the envelope the answer is B chromosome. (looking back D even seems like a better choice versus A but not as good a choice as C)

My confusion isn't with why its B, that makes sense, but more of how to answer questions on the BS section of mcat. I extrapolated my reasoning Damage to nuclear envelope will result in damage to nucleus and possibly DNA. The answer was the more straightforward choice (seems more obvious now). I'm somewhat frustrated in that some questions ask you to reason things out to a certain extent whereas some questions are straightforward no duh does anyone else feel the same way? / Have some advice on this sort of thing?

 

[Leonardo Noto]

99) DDT would most likely initiate cancer or cause a mutation if which of the following structures is damaged?

a) Nuclear Envelope
b) Chromosome
c) Ribosome
d) Histone

Nothing in the passage supports a bridge between DDT and Genetic Material so the question can be interpreted as: Damage to which of the following causes cancer or mutations?

I went with A assuming DDT would damage the nuclear envelope and subsequently damage the DNA within the envelope the answer is B chromosome. (looking back D even seems like a better choice versus A but not as good a choice as C)

My confusion isn't with why its B, that makes sense, but more of how to answer questions on the BS section of mcat. I extrapolated my reasoning Damage to nuclear envelope will result in damage to nucleus and possibly DNA. The answer was the more straightforward choice (seems more obvious now). I'm somewhat frustrated in that some questions ask you to reason things out to a certain extent whereas some questions are straightforward no duh does anyone else feel the same way? / Have some advice on this sort of thing?

You're over-thinking the question. Essentially, it's saying substance X (DDT in this case) causes cancer. What is the most likely mechanism? The most common mechanism, actually the only mechanism, of causing cancer listed there is mutation of DNA, aka: mutation of chromosomes. Changing a histone directly would not likley cause cancer (changing a gene for a histone might; but that would be a mutation). Damaging a nuclear membrane would not likely cause cancer and a chemical does not have to damage the nuclear membrane to reach DNA -- many chemicals go straight through which is the reason why melatonin is a great thing to have on your self (anti-oxidant that passes freely into the nucleus) in case a nuclear bomb goes off in your vicinity. Damaging ribosomes would likely either result in A) the cell replacing the ribosomes, or B) the cell dying; neither of which leads to cancer. Yes, if you really wanted to delve into this subject you could think about epigenetics and confuse yourself; but again, the problem is that your over-thinking a relatively straight forward question, something that is easy to do when you're under stress and the reason why practice questions are so important!

Leonardo Noto
www.leonardonoto.com or follow me on Twitter @DrLeonardoNoto

 

[curt656]

The question is: Cancer or a mutation would most likely be the result if DDT damaged what structure?

Cancer is uncontrolled cell growth due to DNA mutations, but not all mutations result in cancer. The definition of a mutation is: the changing of the structure of a gene. So, chromosome is the best answer.

 

[richkaj]

I understand you too. Just think about the main reason or the cause and effect of the equation. POE helps and try to think of the relationships that may relate to the question without looking at the answers. If you have an idea at first, this may help you find the answer. Most, if not all the time you will have an idea. GO WITH THAT...

 

[sciencebooks]

99) DDT would most likely initiate cancer or cause a mutation if which of the following structures is damaged?

a) Nuclear Envelope
b) Chromosome
c) Ribosome
d) Histone

Nothing in the passage supports a bridge between DDT and Genetic Material so the question can be interpreted as: Damage to which of the following causes cancer or mutations?

I went with A assuming DDT would damage the nuclear envelope and subsequently damage the DNA within the envelope the answer is B chromosome. (looking back D even seems like a better choice versus A but not as good a choice as C)

My confusion isn't with why its B, that makes sense, but more of how to answer questions on the BS section of mcat. I extrapolated my reasoning Damage to nuclear envelope will result in damage to nucleus and possibly DNA. The answer was the more straightforward choice (seems more obvious now). I'm somewhat frustrated in that some questions ask you to reason things out to a certain extent whereas some questions are straightforward no duh does anyone else feel the same way? / Have some advice on this sort of thing?

Yes, there's variation in question difficulty and presentation, but that doesn't seem to be the issue here. Say you didn't know that cancer was caused by a change to a gene. You still could have extrapolated further. Think about it. Why did you choose A? Because you thought it might damage DNA through a process. If you understood the root would be related to DNA, you should have looked to B because it most directly contains DNA where as with A, you'd have to first destroy the envelope to get to it.