Summarize Argument
The author concludes that apples were probably not cultivated in this region 5,000 years ago. This is based on the following:
Today, wild apples are much smaller than cultivated apples found in supermarkets.
In this region, apples of 5,000 years ago were the same size as wild apples native to the region.
Identify and Describe Flaw
The author assumes that cultivated apples 5,000 years ago must have been larger than wild apples from that time. But this overlooks the possibility that wild apples were similar in size to cultivated apples from that time, even if today wild apples are smaller than cultivated apples.
A
fails to consider that even if a plant was not cultivated in a given region at a specific time, it may have been cultivated in nearby regions at that time
The argument concerns only “this region.” Whether apples were cultivated in other regions does not affect the reasoning of the argument.
B
fails to consider that plants that have been cultivated for only a short time may tend to resemble their wild counterparts much more closely than plants that have been cultivated for a long time
The author overlooks the fact that, 5,000 years ago, cultivated and wild apples might have been more similar in size compared to their relative sizes today. We cannot rely on their relative sizes today to conclude that the smaller apples of 5,000 years ago were not cultivated.
C
takes for granted that all apples are either the size of wild apples or the size of the cultivated apples now found in supermarkets
The argument concerns remains of apples in a particular region that are the same size wild apples. The existence of other apples sized in between wild/cultivated doesn’t weaken the argument. So the author doesn’t need to assume there are only two sizes for apples.
D
employs a premise that is incompatible with the conclusion it is supposed to justify
There is no premise that contradicts the conclusion. The conclusion is that apples probably weren’t cultivated 5,000 years ago in this region. None of the premises makes the conclusion impossible to be true.
E
uses a claim that presupposes the truth of its main conclusion as part of the justification for that conclusion
(E) describes circular reasoning. None of the premises assume the truth of the conclusion. The premises include comparison between sizes of apples today, and a claim about sizes of remains of certain apples. The conclusion is about whether those apples were cultivated.
Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that one of the functions of phenazines is to serve as molecular pipelines that give interior bacteria access to essential nutrients in the environment surrounding the colony.
Notable Assumptions
The author assumes that it’s possible for phenazines to have more than one function. The author also assumes that phenazines are able to provide nutrients to interior bacteria.
A
Bacteria colonies that do not produce phenazines form wrinkled surfaces, thus increasing the number of bacteria that are in direct contact with the surrounding environment.
This provides evidence that corroborates the author’s hypothesis. Without phenazines, more bacteria must contact the surrounding environment, possibly to get access to nutrients. This makes the theory that phenazines give interior bacteria access to nutrients more plausible.
B
The rate at which a bacteria colony produces phenazines is determined by the number of foreign bacteria in the environment immediately surrounding the colony.
This connects production of phenazines to foreign bacteria. But this has no clear impact. We want an answer that connects phenazines to the need to access nutrients.
C
When bacteria colonies that do not produce phenazines are buried in nutrient-rich soil, they grow as quickly as colonies that do produce phenazines.
We still have no reason to think phenazines provide nutrients to interior bacteria. If anything, this is in the direction of a weakener, since we might think non-phenazine bacteria shouldn’t grow as quickly when buried in the soil.
D
Bacteria colonies that produce phenazines are better able to fend off other bacteria than are bacteria colonies that do not produce phenazines.
This connects phenazines to ability to fend off other bacteria. But this has no clear connection to the provision of nutrients to interior bacteria.
E
Within bacteria colonies that produce phenazines, interior bacteria are more likely to die than are bacteria along the edges.
It doesn’t help the author’s hypothesis to learn that interior bacteria die more quickly. We would still have no reason to believe phenazines provide nutrients to interior bacteria.