What kind of animals has a water vascular system with tubed feet?
Options:
- (A) animals
- (B) starfish
- (C) reeds
- (D) insects
- (E) warm-blooded
- (F) sponges
- (G) sea coral
- (H) four limbs
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Let's think first: Echinoderms have a unique water vascular system with tube feet. Echinoderms are represented by the starfish. Starfish have a unique water vascular system with tube feet.... So the answer is [(B)]


Adult sperm are capable of producing sperm and what in order to be able to reproduce?
Options:
- (A) Plants growth
- (B) reproduce
- (C) skin cells
- (D) female gametes
- (E) it needs them
- (F) kinetic energy
- (G) estrogen
- (H) vaginas
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Let's think first: Adult sponges produce eggs and sperm. Female gametes are called eggs. Adult sponges produce female gametes and sperm.... So the answer is [(D)]


Many plants go dormant during the 
Options:
- (A) heat or cold
- (B) earth's revolving
- (C) autumnal equinox
- (D) colder and wetter
- (E) It helps them survive
- (F) cloudy and rainy weather
- (G) Plant growth is reduced
- (H) fire conditions
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Let's think first: Many plants respond to the days growing shorter in the fall by going dormant. After the autumnal equinox, days gradually shorten in the Northern Hemisphere. Many plants respond to the autumnal equinox by going dormant.... So the answer is [(C)]


_ is how organisms grow and repair themselves.
Options:
- (A) complex
- (B) recycling
- (C) properties
- (D) fusion
- (E) fission
- (F) bacteria
- (G) Mitosis
- (H) potatoes
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Let's think first: Cell division is how organisms grow and repair themselves. Mitosis is cell division. Mitosis is how organisms grown and repair themselves.... So the answer is [(G)]


What must a chemical reaction overcome before starting?
Options:
- (A) PV=nRT
- (B) heat or cold
- (C) reactants
- (D) energy barrier
- (E) Dehydration
- (F) harmful substances
- (G) resistance
- (H) temperature
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Let's think first: All chemical reactions require activation energy to get started. Activation energy is required to overcome the energy barrier. All chemical reactions must first overcome the energy barrier.... So the answer is [(D)]


What has a centralized nervous system with a brain?
Options:
- (A) Man
- (B) Birds
- (C) leeches
- (D) shark
- (E) evergreens
- (F) salmon
- (G) worms
- (H) pan
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Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Let's think first: Fish have a centralized nervous system with a brain. Sharks are a type of fish. Sharks have a centralized nervous system with a brain.... So the answer is [(D)]