Summarize Argument
The author concludes that evolution doesn’t always optimize an organism’s survival. This conclusion is supported by the example of male moose’s evolution of giant antlers. They evolved these antlers to fight other males; the largest antlers give an evolutionary advantage. But larger antlers make it harder to escape predators. Male moose would be better off, at least in terms of surviving from predators, if they all had smaller antlers.
Describe Method of Reasoning
The author supports a conclusion by using an example.
A
citing an example to cast doubt on a competing argument
Although the author does cite to an example to counter the claim that evolution always optimizes survival of an organism, this claim is not a competing argument. An argument requires a premise and conclusion; an individual claim is not necessarily an argument.
B
employing an analogy in order to dispute a generalization
The author doesn’t use an analogy. An example is not an analogy. Arguments by analogy involve an attempt to identify similarities between two things to support an inference that another similarity exists.
C
challenging a general claim by presenting a counterexample
Th author uses the male moose example to counter the general claim that evolution always optimizes survival of an organism. This general claim wasn’t explicitly laid out, but the author’s conclusion can be interpreted as a rejection of that general claim.
D
disputing the relevance of an example thought to support an opposing view
The author uses the example of male moose to support his own conclusion. This does not constitute disputing the relevance of the example.
E
undermining a claim by showing that it is self-contradictory
The author does not point out that any claim is self-contradictory. A self-contradictory claim is one that either asserts or implies something that is logically inconsistent with another part of the claim.
Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that certain bacteria detect a particular shade of red by monitoring how much energy their chlorophyll produces. This is based on the fact that, when placed into a test tube that has different areas lit with different colors of light, the bacteria move only into areas lit with that shade of red. In addition, the bacteria’s chlorophyll allows them to produce energy more effectively from this shade of red than from any other color.
Notable Assumptions
The author assumes there’s no other explanation for why the bacteria moves only to those areas that are lit with that shade of red.
A
If the chlorophyll is removed from the bacteria, but the bacteria are otherwise unharmed, they no longer show any tendency to move into the areas lit with the particular shade of red.
This strengthens the argument by helping to establish a connection between chlorophyll and moving to that shade of red.
B
The bacteria show little tendency to move into areas containing light in colors other than the particular shade of red, even if their chlorophyll can produce some energy from light in those colors.
This is consistent with the author’s hypothesis. Because those other shades don’t produce energy as effectively, the bacteria tends not to move to those areas.
C
The areas of the test tube lit with the particular shade of red favored by the bacteria are no warmer, on average, than areas lit with other colors.
This strengthens the argument by eliminating the alternate explanation that the bacteria are moving to the areas that are warmer rather than because of the greater energy produced by their chlorophyll.
D
The bacteria show no tendency to move into areas lit with blue even when those areas are lit so brightly that the bacteria’s chlorophyll produces as much energy in those areas as it does in the red areas.
This presents evidence inconsistent with the author’s hypothesis. If the bacteria don’t move to areas lit in blue, even if those areas produce as much energy as the areas lit in the particular shade of red, this suggests the bacteria isn’t moving due to its chlorophyll’s energy.
E
There are species of bacteria that do not contain chlorophyll but do move into areas lit with particular colors when placed in a test tube lit with different colors in different places.
Other bacteria might move toward other lights for other reasons besides chlorophyll. The author never suggested that no bacteria can ever move to any lights through other methods. The conclusion is just that this particular bacteria detects the red light through chlorophyll.
Summary
After a nuclear power plant accident, radioactive isotopes of iodine, tellurium, and cesium were found in the atmosphere downwind. No heavy isotopes were found. The material either came from spent fuel rods or the plant’s core. Spent fuel rods never contain significant quantities of tellurium, and radioactive material ejected directly from the core would include heavy isotopes. However, steam which may have been in contact with the core was released from the plant. The core contains iodine, tellurium, and cesium, which are easily dissolved by steam.
Strongly Supported Conclusions
The radioactive material found in the atmosphere was carried by the steam released from the plant.
A
Radioactive material ejected into the environment directly from a nuclear power plant’s core would not include tellurium isotopes.
This answer is unsupported. We don’t know from the stimulus whether material ejected directly from the core would not include tellurium. We only know that material ejected directly from the core would definitely include heavy isotopes.
B
The radioactive material detected by the researchers was carried into the atmosphere by the steam that was released from the plant.
This answer is strongly supported. If all three radioactive isotopes found are easily dissolved by steam, and all three are found in the plant’s core, then it’s likely that the found material was carried into the atmosphere by the steam.
C
The nuclear power plant’s spent fuel rods were not damaged.
This answer is unsupported. We don’t know from the stimulus whether the spent fuel rods were damaged or not. We only know information about what isotopes spent fuel rods contain.
D
The researchers found some radioactive material from spent fuel rods as well as some material that was ejected into the atmosphere directly from the plant’s core.
This answer is anti-supported. We know from the stimulus that material ejected directly from the core would include heavy isotopes, yet the researchers did not find any heavy isotopes.
E
Spent fuel rods do not contain heavy isotopes in significant quantities.
This answer is unsupported. We don’t know from the stimulus whether spent fuel rods do not contain heavy isotopes. We only know that spent fuel rods do not contain significant amounts of tellurium.