This one was tough for me. Time taken 10 mins.
1. The passage mentions which of the following as a factor that affects the role of P. ochraceus as a keystone species within different habitats?A. The degree to which the habitat is sheltered from waves
>>P. ochraceus occupies an unambiguous keystone role on wave-exposed rocky headlands, in more wave-sheltered habitats the impact of P. ochraceus predation is weak or nonexistent, and at certain sites sand burial is responsible for eliminating mussels.
B. The degree to which other animals within a habitat prey on mussels
>>certain sites sand burial is responsible for eliminating mussels.
C. The fact that mussel populations are often not dominant
within some habitats occupied by P. ochraceus
D. The size of the P. ochraceus
population within the habitat
E. The fact that there is great species diversity within some habitats occupied by P. ochraceus
2. Which of the following, if true, would most clearly support the argument about keystone status advanced in the last sentence of the passage?
Keystone status appears to depend on context, whether of particular geography
or of such factors as community diversity
(for example, a reduction in species diversity may thrust more of the remaining species into keystone roles) and length of species interaction
(since newly arrived species in particular may dramatically affect ecosystems).A. A species of bat is primarily responsible for keeping insect populations within an ecosystem low, and the size of the insect population in turn affects bird species within that ecosystem.
>>community diversity. What troubles me in this is "affects bird species within that ecosystem." Does this mean, BS r thriving .B. A species of iguana occupies a keystone role on certain tropical islands, but does not play that role on adjacent tropical islands that are inhabited by a greater number of animal species.
>>I don't see mentioned anything like that in para. As per OG this is OA. Can anyone elucidate this.. I believe PO habitat is an example for the GC. I am correct?
C. Close observation of a savannah ecosystem reveals that more species occupy keystone roles within that ecosystem than biologists had previously believed
D. As a keystone species of bee becomes more abundant it has a larger effect
on the ecosystem it inhabits.
E. A species of moth that occupies a keystone role in a prairie habitat develops coloration patterns that camouflage it from potential predators.
3. The passage suggests which of the following about the identification of a species as a keystone species?
A. Such an identification depends primarily on the species’ relationship to the dominant species.
B. Such an identification can best be made by removing the species from a particular ecosystem and observing changes that occur in the ecosystem.
C. Such an identification is likely to be less reliable as an ecosystem becomes less diverse.D. Such an identification seems to depend on various factors within the ecosystem.
>>Correct. Keystone status appears to depend on context .....
E. Such an identification can best be made by observing predation behavior.
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