Question

If a species of parasite is to survive, the host organisms must live long enough for the parasite to ----; if the host species becomes ----, so do its parasites.

• A. atrophy.. healthy
• B. reproduce.. extinct
• C. disappear.. widespread
• D. succumb.. nonviable
• E. mate.. infertile

Hint:

In sentences with two blanks, try to solve for one blank first. Often, one is more constrained or obvious than the other. Once you have a good fit for one blank, you can test its partner word from the same option.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
This sentence describes the biological dependency of a parasite on its host. The sentence is in two parts, each describing a condition for the parasite's survival or demise.
Step 2: Detailed Explanation:
For the first blank, we need to identify the primary biological imperative for a species' survival. The host must live long enough for the parasite to do what? The most fundamental action for the continuation of a species is to create offspring, i.e., to reproduce.
For the second blank, the sentence sets up a parallel fate: "if the host species becomes ----, so do its parasites." This means whatever happens to the host also happens to the parasite. If the host species dies out, or becomes extinct, the parasite, which depends on it, will also become extinct.
Let's check the pair: "the host organisms must live long enough for the parasite to reproduce; if the host species becomes extinct, so do its parasites." This statement is biologically and logically correct. The other pairs create contradictions. For instance, in (C), if the host becomes widespread, the parasite would likely thrive, not disappear.
Step 3: Final Answer:
The words "reproduce" and "extinct" correctly fill the blanks, reflecting the biological principles of species survival and dependency.