What is a main component of a virus?
Options:
- (A) Something that causes allergies
- (B) Leptospirosis
- (C) Localized damage
- (D) heat produced
- (E) deoxyribonucleic acid
- (F) Chemical energy
- (G) direct damage to the lungs
- (H) It helps them survive
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Let's think first: Viruses contain DNA but not much else. DNA DNA is deoxyribonucleic acid. Viruses contain deosyribonucleic acid, but not much else.... So the answer is [(E)]

What is needed for changes to occur?
Options:
- (A) exercise
- (B) mutations
- (C) growth
- (D) healthy animals
- (E) environment
- (F) evaporation
- (G) Exfoliation
- (H) births
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Let's think first: Mutations are essential for evolution to occur. Evolution Change through time. Mutations are essential for changes to occur.... So the answer is [(B)]

Energy enters what in the form of sunlight or chemical compounds.
Options:
- (A) biomes
- (B) fire
- (C) light
- (D) Energy.
- (E) Energy
- (F) LEDs
- (G) propagate
- (H) photons
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Let's think first: Energy enters ecosystems in the form of sunlight or chemical compounds. Biomes are global ecosystems. Energy enters biomes in the form of sunlight or chemical compounds.... So the answer is [(A)]

The two-chambered heart of some backboned aquatic animals is part of their:
Options:
- (A) aerobic capacity
- (B) three-chambered heart
- (C) biological diversity
- (D) it keeps an organism warm
- (E) the body's largest organ
- (F) circulatory system
- (G) salmon
- (H) swimming system
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Let's think first: Fish have a circulatory system with a two-chambered heart. Fish are backboned aquatic animals. Some backboned aquatic animals have a circulatory system with a two-chambered heart.... So the answer is [(F)]

What can a certain protein affect in meat?
Options:
- (A) health
- (B) piousness
- (C) stamina
- (D) retina
- (E) toughness
- (F) liveliness
- (G) saltiness
- (H) Energy
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Let's think first: Cartilage is a tough tissue that contains a protein called collagen. Collagen contributes to meat toughness. A protein contributes to meat toughness.... So the answer is [(E)]

Which is a requirement for life?
Options:
- (A) glucose
- (B) hydration
- (C) sunlight
- (D) scandium
- (E) recovery
- (F) oxygen
- (G) uranium
- (H) radon
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Let's think first: Oxygen is essential for cellular respiration for all aerobic organisms. Cellular respiration is a requirement for life. Oxygen is a requirement for life.... So the answer is [(F)]