(Q).
Q: What occurs when a former inhabited area gets 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? 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? Choices: - claw - cocoon - membrane - exoskeleton A:
(A).
exoskeleton