The similarity between ichthyosaurs and fish is an example of converge

Question

The similarity between ichthyosaurs and fish is an example of convergence, a process by which different classes of organisms adapt to the same environment by independently developing one or more similar external body features. Ichthyosaurs were marine reptiles and thus do not belong to the same class of organisms as fish. However, ichthyosaurs adapted to their marine environment by converging on external body features similar to those of fish. Most strikingly, ichthyosaurs, like fish, had fins.

If the statements above are true, which one of the following is an inference that can be properly drawn on the basis of them?

(A) The members of a single class of organisms that inhabit the same environment must be identical in all their external body features.

(B) The members of a single class of organisms must exhibit one or more similar external body features that differentiate that class from all other classes of organisms.

(C) It is only as a result of adaptation to similar environments that one class of organisms develops external body features similar to those of another class of organisms.

(D) An organism does not necessarily belong to a class simply because the organism has one or more external body features similar to those of members of that class.

(E) Whenever two classes of organisms share the same environment, members of one class will differ from members of the other class in several external body features.

MahmoudFawzy · Answer

A,B,E are not mentioned in the stimulus.
C is too extreme because of "only"

D can be correctly inferred from the example of Ichthyosaurs,
which is an organism that does not belong to a class of "fish" although it has one external body feature (fins) similar to that of the "fish" class.

Sajjad1994 · Answer

Explanation

A fairly straightforward idea here: Ichthyosaurs, a past form of marine reptile, were not fish, but through a process known as convergence developed similar external body features as fish in order to adapt to the same marine environment. Not much choice here but to test the choices for a valid inference.  (D) wins  hands down: The ichthyosaur, thanks to convergence, is the perfect example of an organism that has one or more external body features similar to those of members of a class (fish) it does not belong to.

(A)  is too extreme. Even member of the same class that live in the same environment need not be identical in all their external body features; nothing in the passage disallows slight variation between such individuals of the same class.

(B)  may sound reasonable, but is not in fact inferable from the stimulus. For all we know, convergence is so pervasive in some cases that there are classes of organisms whose members don’t exhibit one such unique external body feature that differentiate that class from all other classes.

(C)  Just because the phenomenon described is the result of adaptation to similar environments doesn’t mean that we can infer that this is the only way that two classes of organisms can come to have similar external body features.

(E)  No, it’s possible that they may not differ in any external body features (for all we know, it may be different internal features that differentiate the two classes), or they may differ in exactly one external body feature.

Answer: D

Hope it helps

Priyanshi245 · Answer

How is D the answer? It is not an inference followed from the author’s arguments.

guddo · Answer

The similarity between ichthyosaurs and fish is an example of convergence, a process by which different classes of organisms adapt to the same environment by independently developing one or more similar external body features. Ichthyosaurs were marine reptiles and thus do not belong to the same class of organisms as fish. However, ichthyosaurs adapted to their marine environment by converging on external body features similar to those of fish. Most strikingly, ichthyosaurs, like fish, had fins.
 
 If the statements above are true, which one of the following is an inference that can be properly drawn on the basis of them?

The passage says ichthyosaurs had some external features similar to fish, especially fins, but they were marine reptiles, not fish. So having a feature similar to members of a class does not necessarily mean belonging to that class.  The key point is that external similarity does not prove classification .

(A) The members of a single class of organisms that inhabit the same environment must be identical in all their external body features.

Wrong. The passage says different classes can develop some similar features, not that members of one class must be identical.

(B) The members of a single class of organisms must exhibit one or more similar external body features that differentiate that class from all other classes of organisms.

Wrong. The passage actually suggests the opposite: organisms from different classes can share similar external features.

(C) It is only as a result of adaptation to similar environments that one class of organisms develops external body features similar to those of another class of organisms.

Wrong. Too strong. The passage gives convergence as one process, but it does not say similar features can arise  only  this way.

(D) An organism does not necessarily belong to a class simply because the organism has one or more external body features similar to those of members of that class.

Correct. Ichthyosaurs had fins like fish, but they were reptiles, not fish. So similar external body features alone do not determine class membership.

(E) Whenever two classes of organisms share the same environment, members of one class will differ from members of the other class in several external body features.

Wrong. The passage says different classes in the same environment may develop similar features, not that they will necessarily differ in several features.

Answer: (D)

The similarity between ichthyosaurs and fish is an example of converge

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The similarity between ichthyosaurs and fish is an example of converge

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

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