Critical Analysis & Reasoning Skills Practice Questions: 13 | Critical Analysis & Reasoning Skills for MCAT PDF Download

For years, anecdotal evidence from around the world has indicated that amphibians are facing significant threats. Now, thanks to the collaborative efforts of scientists involved with the Global Amphibian Assessment, there is concrete proof to support this hypothesis. Amphibians possess unique vulnerabilities due to their permeable skin and specific habitat requirements during their metamorphosis. Studies show that they are at risk due to factors such as global climate change, depletion of the ozone layer leading to increased exposure to ultraviolet rays, disruption of migratory pathways, wetland drainage, pesticide pollution, erosion and sedimentation, and exposure to unknown pathogens through the introduction of non-native species. In essence, human progress is responsible for the decline and loss of amphibian populations.

The permeable skin of amphibians, including frogs and newts, makes them susceptible to various pollutants. Increased ultraviolet radiation has been found to have detrimental effects on amphibian eggs, causing mortality and deformities. Amphibians require clear pathways between land and water to complete their life cycle, but road construction and swamp drainage for urban development have eliminated many of these crucial routes worldwide. The same sensitivity that allows pollution to harm young amphibians also makes them vulnerable to fungal and other pathogens transmitted by pet releases. The emergence of infectious diseases has led to the complete extinction of entire amphibian populations in Australia and the Americas.

Amphibians have long been considered an environmental health indicator by scientists. Areas experiencing significant declines in amphibian populations are often associated with environmental degradation as a major contributing factor. Amphibians are not adaptable creatures; they require clean water for egg-laying and clean air to breathe once they reach adulthood. Their unique dual life as aquatic and land-dwelling animals puts them at risk of exposure to pollutants and other hazards from both environments.

According to the findings of the Global Amphibian Assessment, nearly one-third of the world's amphibian species are immediately threatened with extinction, and nearly half of all species are experiencing population decline. The countries with the highest numbers of threatened species are Colombia, Mexico, and Ecuador, while the highest percentages of threatened species are found in the Caribbean. For instance, in Haiti, nine out of ten amphibian species are threatened, while in Jamaica, it's eight out of ten, and in Puerto Rico, seven out of ten. Only 1 percent of the studied species worldwide have seen any increase in population.

The passage concludes that the decline of amphibians is not only a disaster for them but also potentially for the entire Earth. Even recent amphibian pandemics could be linked to global environmental changes. While amphibians are highly sensitive to such changes, the passage suggests that other creatures like reptiles, fish, birds, and mammals may also be affected. The threat faced by equatorial amphibians may be an initial indication of an impending global catastrophe. The frogs and newts of our world are serving as a warning that continued habitat destruction in the name of progress could ultimately lead to the destruction of all living beings.
Q.1. The central thesis of the passage is that:
(a) the extinction of amphibians is due to global warming.
(b) amphibians really are a barometer of environmental health.
(c) only equatorial amphibians are currently under siege.
(d) amphibians’ “double life” on land and in water may end up saving them.

Correct Answer is Option (b)
The central thesis of the passage is that amphibians are indeed a barometer of environmental health. The passage discusses how the decline and extinction of amphibian species are indicative of environmental degradation caused by factors such as global climate change, pollution, habitat destruction, and the introduction of non-native species. The passage highlights the vulnerability of amphibians to environmental changes and asserts that their decline serves as an indicator of broader environmental issues. Therefore, option B is the correct answer.

Q.2. The passage implies that the Global Amphibian Assessment has done science a

favor by:
(a) setting forth a hypothesis that connects the environment to species decline.
(b) eliminating the need to study the connection between extinction and environment.
(c) refuting a contention that had existed purely through anecdotal evidence.
(d) collecting data to prove something that was previously just a hypothesis.

Correct Answer is Option (d)
The passage implies that the Global Amphibian Assessment has contributed significantly to science by collecting data to prove something that was previously a hypothesis. The passage states that anecdotal evidence from around the world indicated the decline of amphibians, but it was the concerted effort of scientists involved with the Global Amphibian Assessment that provided concrete proof to support this hypothesis. By collecting and analyzing data, the Global Amphibian Assessment has helped move beyond anecdotal evidence and establish the reality of amphibian population declines and extinctions. Therefore, option D is the correct answer.

Q.3. Which of the following assertions does the author support with an example?
I. The permeable skin of amphibians allows for the entry of pollutants.
II. Amphibians are susceptible to unfamiliar pathogens.
III. Most threatened species are in the Caribbean.
(a) I only
(b) III only
(c) I and II only
(d) II and III only

Correct Answer is Option (d)
The correct answer is D, as it aligns with the Evaluation question asking about unsupported assertions. To determine the validity of each assertion, it is necessary to refer back to the text and locate the corresponding information. Assertion I is unsupported as the passage does not provide specific examples of pollutants harming amphibians, making choices A and C incorrect. However, Assertion II is supported in the passage's third paragraph, which mentions an emerging infectious disease that has led to the extinction of entire amphibian populations in Australia and the Americas. Assertion III is also supported, as the passage provides a list of countries with the highest percentages of threatened species. As both choices B and D include Assertion III, the correct answer is (d)

Q.4. Which of the following predictors is MOST analogous to amphibians as described in the fourth paragraph?
(a) biomarkers in the blood predicting mental illness
(b) red sky at night predicting high pressure and dry air
(c) canaries in a coal mine predicting dangerous gases
(d) groundhog’s shadow predicting longer winter

Correct Answer is Option (c)
The analogy that best matches the description of amphibians in the fourth paragraph is canaries in a coal mine predicting dangerous gases. The passage mentions that amphibians are considered an environmental health indicator, similar to canaries being used in coal mines to detect dangerous gases. Both amphibians and canaries serve as early warning signs for potential hazards in their respective environments. Therefore, option C is the correct answer.

Q.5. According to this passage, the continued degradation of the environment may well lead to:
(a) global pandemics
(b) floods and droughts
(c) human deformities
(d) decline among insects

Correct Answer is Option (a)
According to the passage, the continued degradation of the environment may indeed lead to global pandemics. The passage suggests that even recent pandemics among amphibians could be caused by global environmental changes. It further implies that the threats faced by amphibians may be an indication of a global catastrophe to come, potentially affecting other creatures as well. Therefore, option A is the correct answer.