PrepTest 87, Section 2, Question 18
Some killer whales eat fish exclusively, but others also eat seals. Different groups of killer whales "chatter" in distinct dialects, and the dialects of seal-eating killer whales are recognizably different from those of killer whales that do not eat seals. Harbor seals use their ability to distinguish between different killer-whale dialects to avoid seal-eating killer whales. Marine biologists hypothesize that young harbor seals start with an aversion to all killer whales but then learn to ignore those that do not eat seals.
Some killer whales eat fish exclusively, but others also eat seals. Different groups of killer whales "chatter" in distinct dialects, and the dialects of seal-eating killer whales are recognizably different from those of killer whales that do not eat seals. Harbor seals use their ability to distinguish between different killer-whale dialects to avoid seal-eating killer whales. Marine biologists hypothesize that young harbor seals start with an aversion to all killer whales but then learn to ignore those that do not eat seals.
Some killer whales eat fish exclusively, but others also eat seals. Different groups of killer whales "chatter" in distinct dialects, and the dialects of seal-eating killer whales are recognizably different from those of killer whales that do not eat seals. Harbor seals use their ability to distinguish between different killer-whale dialects to avoid seal-eating killer whales. Marine biologists hypothesize that young harbor seals start with an aversion to all killer whales but then learn to ignore those that do not eat seals.
Some killer whales eat fish exclusively, but others also eat seals. Different groups of killer whales "chatter" in distinct dialects, and the dialects of seal-eating killer whales are recognizably different from those of killer whales that do not eat seals. Harbor seals use their ability to distinguish between different killer-whale dialects to avoid seal-eating killer whales. Marine biologists hypothesize that young harbor seals start with an aversion to all killer whales but then learn to ignore those that do not eat seals.
Which one of the following, if true, provides the strongest support for the biologists' hypothesis?
Killer whales that eat seals also eat other marine mammals that are similar in size to seals.
Unlike harbor seals, which can hear killer-whale chatter even at great distances, most fish cannot hear that chatter, even close at hand.
When mature harbor seals first listen to the recorded chatter of killer whales that eat only fish but whose dialect is unfamiliar, the seals rapidly swim away from the sound.
Young harbor seals show no natural aversion to any seal predators other than killer whales.
If a fish-eating killer whale mistakenly attacks a harbor seal, that seal, if it survives, will subsequently avoid all killer whales that chatter in the attacker's dialect, but other harbor seals will not.
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