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Author Topic: LR Help  (Read 550 times)

Eric9064

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LR Help
« on: August 08, 2007, 02:05:09 PM »
In experiments in which certain kinds of bacteria were placed in a generous supply of nutrients, the populations of bacteria grew rapidly and genetic mutations occurred at random in the populations. these experiments show that all gentic mutuation is random.

Which one of th following, if true, enables teh conclusion to be properly drawn?

a) Either all genetic mutations are random or none are random

c) If all genetic mutations in bacteria are random, then all genetic mutations in every othdr life form are random.


Not sure why A is the answer and I would appreciate any insight people could give.


babyeatsdingo

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Re: LR Help
« Reply #1 on: August 08, 2007, 02:14:46 PM »
In experiments in which certain kinds of bacteria were placed in a generous supply of nutrients, the populations of bacteria grew rapidly and genetic mutations occurred at random in the populations. these experiments show that all gentic mutuation is random.

Which one of th following, if true, enables teh conclusion to be properly drawn?

a) Either all genetic mutations are random or none are random

c) If all genetic mutations in bacteria are random, then all genetic mutations in every othdr life form are random.


Not sure why A is the answer and I would appreciate any insight people could give.



If A is true, and for the sake of answering the question we assume so, then a single case like that provided in the story above where genetic mutations occur at random means it is false that no mutations are random which means it must be true that all mutations are random.

Said otherwise, answer A sets up a dilemma. The stimulus eliminates one of the horns of the dilemma that A sets up (i.e., no mutations are random) which implies the other horn (i.e., all mutations are random) must obtain.

sg7007

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Re: LR Help
« Reply #2 on: August 08, 2007, 07:38:09 PM »
In experiments in which certain kinds of bacteria were placed in a generous supply of nutrients, the populations of bacteria grew rapidly and genetic mutations occurred at random in the populations. these experiments show that all gentic mutuation is random.

Which one of th following, if true, enables teh conclusion to be properly drawn?

a) Either all genetic mutations are random or none are random

c) If all genetic mutations in bacteria are random, then all genetic mutations in every othdr life form are random.


Not sure why A is the answer and I would appreciate any insight people could give.



See if what I'm saying is right.

The conclusion states, "these experiments show that all genetic mutation is random." Part of the premise states that genetic mutations occured at random. But, the premise is just a premise, we don't know for sure if the genetic mutations are random. The question stem says, though, that the answers are all considered to be true. Then, if the answer, (A) is true, then the conclusion should logically follow because all genetic mutations, if any, are random, and the premise states that genetic mutations DID occur in the experiment. The answer, (C) is simply irrelevant.

PNym

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Re: LR Help
« Reply #3 on: August 08, 2007, 10:07:37 PM »
In experiments in which certain kinds of bacteria were placed in a generous supply of nutrients, the populations of bacteria grew rapidly and genetic mutations occurred at random in the populations. these experiments show that all gentic mutuation is random.

Which one of th following, if true, enables teh conclusion to be properly drawn?

a) Either all genetic mutations are random or none are random

c) If all genetic mutations in bacteria are random, then all genetic mutations in every othdr life form are random.


Not sure why A is the answer and I would appreciate any insight people could give.



The argument concludes by stating that all genetic mutation is random. The author supports this conclusion with the premise that one experiment showed random mutations occurring in bacteria.

Since the experiment shows that some mutations are random, but the conclusion states that all mutations are random, you need a premise that changes some -> all.

A) does that. A) says that either mutations are all random or none are random. Since the experiment shows that some mutations are random, when combined with A), that premise leads to the conclusion that all are random.

Since some are random, then the conclusion "none are random" can be excluded.