How are atolls built?
Options:
- (A) important habitats
- (B) By coral exoskeletons
- (C) by fish
- (D) with machines
- (E) by a type of eel
- (F) It used to be covered by water
- (G) The area was once underwater
- (H) reusing materials
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Let's think first: Many corals secrete an exoskeleton that builds up to become a coral reef. An atoll is the third type of reef. Atolls are built by corals secreting an exoskeleton.... So the answer is [(B)]

What is essential for cellular respiration for all aerobic organisms.
Options:
- (A) electron
- (B) glucose
- (C) Energy
- (D) Energy.
- (E) chemicals
- (F) Plants
- (G) fungi
- (H) bacteria
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Let's think first: Oxygen is essential for cellular respiration for all aerobic organisms. Oxygen, for example, is produced by plants. Plants are essential for cellular respiration for all aerobic organisms.... So the answer is [(F)]

What involves a sperm and egg fusing to form a diploid zygote?
Options:
- (A) Leptospirosis
- (B) produce offspring
- (C) allow growth
- (D) sexual reproduction
- (E) metabolic reaction
- (F) peachleaf willow
- (G) rapid expansion
- (H) Plant reproduction
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Let's think first: Fertilization occurs when a sperm and an egg fuse to form a diploid zygote. Sexual reproduction requires formation of gametes, followed by fertilization. Sexual reproduction involves a sperm and egg fusing to form a diploid zygote.... So the answer is [(D)]