June 2007 LSAT Question Explanations June 2007 - Sec 2 - LR...

June 2007 - Sec 2 - LR - Q14

Video Transcript:

0:05
question fourteen: A cup of raw milk, after being heated in the microwave oven to
0:12
50 degrees Celsius, contains half its initial concentration of a particular enzyme,
0:17
lysozyme. If, however the milk reaches that temperature through exposure to a
0:23
conventional heat source of 50 degrees Celsius, it will contain nearly all of
0:28
its initial concentration of the enzyme. Therefore, what destroys the enzyme
0:35
is not heat but
0:37
microwaves, which generate heat. So, first step argument or facts? Clearly an argument structural
0:45
indicator of 'therefore'. The conclusion being that what destroys the enzyme is not heat
0:51
but microwaves which generate heat. And how do we know that? Well, we have a cup of
0:59
raw milk that was heated in a microwave oven to 50 degrees Celsius, contain half
1:04
of its initial concentration of a particular enzyme Lysozyme. However, when I used
1:13
a conventional heat source of 50 degrees we had nearly all the lysozyme present. So, based on
1:22
that and then those are our premises the author concludes that it's not heat but
1:29
microwaves that are destroying this enzyme lysozyme. So if you notice this is a
1:36
cause and effect argument. And if you notice, what is the observed effect that we are trying to
1:40
explain here? It is the missing enzyme lysozyme. And what is this author's proposed cause for this
1:49
observed effect. Well it's not heat but
1:53
microwaves which generate heat. So now that we have a clear understanding of this
1:59
argument it is a cause and effect argument let's procedure the questions stem which says:
2:04
Which of the following, if true, most seriously weekens the argument? So this is clearly a
2:11
weaken question. So, we were trying to weaken this argument that what is
2:17
destroying this enzyme lysozyme is not heat but microwaves. So let's take a
2:24
look here at (A). Heating raw milk in a microwave oven to temperature of 100
2:31
degrees Celsius destroyes nearly all of the lysozyme initially present in that milk.
2:37
And you notice if anything
2:40
(A) seems to strengthen this argument by showing where we get even hotter in a
2:45
microwave even more lysozyme disappears. It definitely does not weaken so (A) is out. (B)
2:53
Enzymes in raw milk that are destroyed through excessive heating can be replaced by
2:59
adding enzymes that have been extracted from other sources. And (B) is
3:03
completely irrelevant. Ahat difference does it make me to our argument if these
3:08
enzymes that are being destroyed can later be replaced. Its not what this argument
3:15
is about so (B) does not follow. Moving to (C): A liquid exposed to a conventional heat
3:23
source of exactly 50 degrees Celsius will reach that temperature more slowly
3:28
than it would if it were exposed to a conventional heat source hotter than 50 degrees Celsius.
3:34
And obviously thats groundbreaking. If you're exposed to a lower temperature you will reach that temperature
3:38
more slowly than if you were exposed to a higher temperature. I mean great, but again
3:45
this is not about being hotter than 50 degrees its about 50 degrees. (C) is completely irrelevant so
3:53
(C) is out. Moving to (D): Milk that has been heated in a microwave oven does not taste
4:00
noticeably different from milk that has been briefly heated by exposure to a
4:04
conventional heat source. Again completely irrelevant this is not about
4:09
how the milk tastes. So (D) is out, which brings as process of elimination to (E): Heating
4:19
any liquid by microwave creates small zones within it that are much hotter
4:23
than the overall temperature in the liquid will ultimately reach. And you
4:28
notice that (E)
4:29
does weaken this argument that it's not the heat but rather the microwaves by
4:35
showing that when you use a microwave even though it's only 50 degrees
4:40
Celsius small zones are created that are much hotter than the overall temperature
4:46
that the liquid will reach. So, while this milk ultimately reached 50 degrees Celsius
4:52
these small zones that were created within it due to the microwave are much hotter.
4:58
So it proposes as an alternate cause to our observed effect that it's not actually the
5:05
microwaves but it is the heat. Particularly the heat from these small zones. So, (E) again weakens the
5:19
argument by pointing out a possible alternate cause to the observed effect of the
5:25
missing enzyme lysozyme.