(Q).
Q: What occurs when a former inhabited area gets disturbed? Read this paragraph and choose the correct option from the provided answers: Secondary succession occurs in a formerly inhabited area that was disturbed. Choices: - tertiary succession - primary succession - tropical succession - secondary succession A:
(A).
secondary succession

(Q).
Q: What gas comprises about three-fourths of earth's atmosphere? Read this paragraph and choose the correct option from the provided answers: Nitrogen is another common element found in living things. It is needed to form both proteins and nucleic acids such as DNA. Nitrogen gas makes up 78 percent of Earth's atmosphere. In the nitrogen cycle, nitrogen flows back and forth between the atmosphere and living things. You can see how it happens in Figure below . Several different types of bacteria play major roles in the cycle. Choices: - hydrogen - carbon dioxide - oxygen - nitrogen A:
(A).
nitrogen

(Q).
Q: What rigid external structure protects shellfish and other animals and provides points of attachment for the muscles that move the appendages? Read this paragraph and choose the correct option from the provided answers: Choices: - claw - cocoon - membrane - exoskeleton A:
(A).
exoskeleton