Freshwater biomes contain water that contains little to no what?
Options:
- (A) cations
- (B) Acids
- (C) Nutrients
- (D) sodium
- (E) Pollution
- (F) animals
- (G) plants
- (H) water
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Let's think first: Freshwater biomes have water that contains little or no salt. Another name for salt is sodium. Freshwater biomes have water that contains little or not sodium.... So the answer is [(D)]

What are organisms that make food for themselves and other organisms?
Options:
- (A) mushrooms
- (B) green plants
- (C) plants
- (D) mammals
- (E) agriculture
- (F) honeybees
- (G) photosynthesis
- (H) animals
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Let's think first: Producers are organisms that produce food for themselves and other organisms. Green plants are producers . Green plants are organisms that make food for themselves and other organisms.... So the answer is [(B)]

What are cells the basic units of the structure and function of?
Options:
- (A) humans
- (B) Most plants
- (C) animals
- (D) Cell service
- (E) Organisms
- (F) mammals
- (G) Lego cells
- (H) Buildings
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Let's think first: Cells are the basic units of the structure and function of living things. An organism is a living thing. Cells are the basic units of the structure and function of an organism.... So the answer is [(E)]

Neurotransmitters and hormones are what in their function?
Options:
- (A) cells
- (B) organic
- (C) inorganic
- (D) complex
- (E) Vibrates
- (F) warm
- (G) properties
- (H) similar
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Let's think first: Hormones are chemical messengers that control many body functions. Neurotransmitters are chemical messengers in the brain. Hormones and neurotransmitters behave in common ways.... So the answer is [(H)]

How do ost frogs breathe as tadpoles?
Options:
- (A) gills
- (B) sucking in air
- (C) oxygen
- (D) lungs
- (E) ligt
- (F) nektar
- (G) skin
- (H) ovaries
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Let's think first: Most amphibians breathe with gills as larvae and with lungs as adults. Frogs are the most durable of the amphibians. Most frogs breathe with gills as larvae and with lungs as adults.... So the answer is [(A)]

What are molecules that the immune system recognizes as foreign to the physical entity?
Options:
- (A) bacteria
- (B) proteins
- (C) antibodies
- (D) Allergies
- (E) negative
- (F) immunities
- (G) parasites
- (H) antigens
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Let's think first: Antigens are molecules that the immune system recognizes as foreign to the body. Bodies are physical entities. Antigens are molecules that the immune system recognizes as foreign to the physical entity.... So the answer is [(H)]