What has circulatory system with a two-chambered heart?
Options:
- (A) sharks
- (B) trout
- (C) pan
- (D) toads
- (E) Birds
- (F) animals
- (G) mammals
- (H) Man
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Let's think first: Fish have a circulatory system with a two-chambered heart. Fish species include salmon and trout. Salmon and trout have a circulatory system with a two-chambered heart.... So the answer is [(B)]

What do viruses contain?
Options:
- (A) electromagnetic energy
- (B) light energy
- (C) resistance
- (D) contamination
- (E) Deoxyribonucleicacid
- (F) Chemical energy
- (G) harmful substances
- (H) Leptospirosis
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Let's think first: Viruses contain DNA but not much else. DNA stands for Deoxyribonucleicacid. Viruses contain Deoxyribonucleicacid but not much else.... So the answer is [(E)]

Trees have woody stems covered with what?
Options:
- (A) heat energy
- (B) thin skin
- (C) protective skin
- (D) skinny cells
- (E) white skin
- (F) Chlorophyll
- (G) Organic compounds
- (H) looseness
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Let's think first: Trees have woody stems covered with bark. On the outside is a protective skin of bark made mainly of cork. Trees have woody stems covered with protective skin.... So the answer is [(C)]

The loss in length of what causes cells to age?
Options:
- (A) fur and fat
- (B) layers of fat
- (C) cell membrane
- (D) sunlight
- (E) Chlorophyll
- (F) telomeres
- (G) programmed cell death
- (H) cancer
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Let's think first: Aging occurs as cells lose their ability to divide. Portions of the telomeres are lost each time a cell divides. Aging occurs as cells lose their telomeres.... So the answer is [(F)]

What process helps provide resources for producers to create food?
Options:
- (A) animals
- (B) Exfoliation
- (C) decomposition
- (D) mastication
- (E) recycling
- (F) reproduction
- (G) ejaculation
- (H) Converting waste.
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Let's think first: Producers use energy and inorganic molecules to make food. Decomposition is the breakdown of organic molecules into inorganic molecules. Decomposition provides resources for producers to create food.... So the answer is [(C)]

What is critical?
Options:
- (A) Balance
- (B) oxygen
- (C) recovery
- (D) Electrical
- (E) heat
- (F) sun's heat
- (G) stay warm
- (H) stamina
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Let's think first: Balance is the ability to sense and maintain body position. Body position is critical. Balance is critical.... So the answer is [(A)]