The golden toad of Costa Rica, whose beauty and rarity inspired an unu

1.
"Except" questions require us to test the five answer choices to determine the "odd
one out." It is beneficial to use the True / False technique: label each answer choice
with a T or an F and look for the odd one out (which, in this case, we should expect
to be an F).
(A) True. The third sentence of the second paragraph characterizes changing
weather patterns due to global warming as a subtle effect of human activities.
(B) True. The first two sentences of the second paragraph classify both toads and
frogs as amphibians. Later in the second paragraph, the passage explains that
amphibians have permeable skin.
(C) True. The third sentence of the second paragraph states explicitly that scientists
“hypothesize” that human activity is responsible for the global decline of amphibious
populations. Since a hypothesis is an educated guess rather than a fact, it is true
that human activity may not be responsible for the decline.
(D) True. The second sentence of the first paragraph states that money was raised
in the United States to establish the Monteverde Cloud Forest Preserve.
(E) CORRECT. False. The passage offers no information about the number of
salamander species in Costa Rica that have disappeared since the late 1980s. We
cannot assume that this omission indicates a lesser number than either toad or frog
species.
2.
The correct answer to an inference question on the GMAT must be supported by
evidence from the text without need for external information.
(A) The passage states that twenty of the fifty species of frogs and toads known to
once inhabit a 30-square-kilometer area near Monteverde have disappeared.
Nothing is implied about the areas of Costa Rica farther from Monteverde.

(B) CORRECT. The passage suggests that amphibians are able to offer humans
early notification of the deterioration of the environment because of the amphibians’
permeable skin. Thus, permeable skin must be a characteristic that humans do not
possess.

(C) No causal relationship between the build-up of pollutants in the atmosphere and
a decrease in atmospheric ozone is suggested in the passage.

(D) The author states that humans would be wise to heed the warning offered by the
decline of amphibious populations, but nothing suggests that humans normally do
not take signals of environmental deterioration seriously.

(E) The passage does not compare Costa Rica’s environmental problems to those of
other countries.

3.
In the second paragraph, the author mentions “the more subtle effects of human
activity on the world's ecosystems,” and then lists three of these effects: the build-up
of pollutants, the decrease in atmospheric ozone, and changing weather patterns
due to global warming, all of which, scientists hypothesize, “are beginning to take
their toll.” The key to answering this question correctly is to recognize, in context,
what these effects have in common.

(A) Nowhere does the passage suggest or imply that these changes are not easily
recognized by sophisticated testing equipment.

(B) CORRECT. All of these effects happen on a global scale, so their immediate
consequences on specific ecosystems are difficult to recognize. Furthermore, the
passage states these effects are “beginning to take their toll,” indicating that the
effects happen over time.

(C) Scientists hypothesize that these effects do affect amphibians, but nothing in the
passage indicates that only small animal species such as amphibians are affected.
In fact, the final sentence of the passage indicates that humans too might be affected
by these environmental changes.

(D) The passage states that scientists hypothesize about the consequences of these
subtle effects; this indicates that scientists do in fact discuss these effects.

(E) The passage indicates that the consequences of these effects are global,
causing disruptions in amphibious populations “the world over.”

4.
This question is really just a disguised inference question. The correct answer to an
inference question must be directly supported by evidence from the text.
(A) CORRECT. The first sentence of the passage states that the beauty of Costa
Rica’s golden toad was one factor that generated interest from a public normally
unconcerned with amphibians. Thus, many amphibians must not be considered
beautiful.

(B) The passage indicates that habitat preservation in isolation - no matter the size of
the habitat - was not enough to save the golden toad. Instead, scientists theorize that
broader ecological issues are harming the world’s amphibious populations.

(C) The second paragraph tells us that amphibian populations have been declining
around the world.

(D) This is a misinterpretation of the analogy used in the second paragraph. The
author is implying that amphibians may provide humans an early warning for
detrimental changes to the environment, just as canaries provide humans an
indication of detrimental conditions in coal mines.

(E) The final sentence of the passage indicates that humans would be wise to
recognize the potential environmental deterioration signified by declining amphibious
population, but it is too extreme to infer that no humans consider this decline a threat
to humans. In fact, the author of the passage seems to consider it a threat!

5.
The first paragraph of the passage discusses a specific case in which a particular
amphibian mysteriously disappeared from its habitat and suggests that humans may
have been in some way responsible for its demise. The second paragraph explains
that declining amphibious populations are actually a global trend and hypothesizes
that a variety of human activities are harming these environmentally sensitive
animals.

(A) The example of the golden toad is too narrow and specific to be the primary
purpose of the passage. Instead, the golden toad is used as an example of a much
larger trend.

(B) Though this answer choice is on the right track, it is too extreme to say that
human activity is “undoubtedly” to blame for the global decline of amphibian
populations. Instead the passage indicates that scientists “hypothesize” that human
activity is responsible.

(C) An attempt to convince humans to minimize the output of pollutants is never
mentioned in the passage.

(D) CORRECT. The passage discusses the mysterious disappearance of
amphibious populations worldwide and hypothesizes that subtle effects on
ecosystems resulting from human activity may be responsible for these
disappearances.

(E) The final sentence of the passage does urge humans to pay attention to
declining amphibian populations, but this is not the primary purpose of the passage. Moreover, the passage specifically discusses amphibians, while this answer choice
broadly mentions “important environmental changes” rather than focusing on
amphibians.