Ans: (D)
Question: What are a source of food for many fish species?
Options:
- (A) layers of fat
- (B) bird species
- (C) human species
- (D) keystone species
- (E) Organic compounds
- (F) barnacles
- (G) gastropod shells
- (H) species of deer
CoT: Sponges are a source of food for many species of fish. Sponges are also keystone species. Keystone species are a source of food for many fish species.

Ans: (A)
Question: What are endothermic vertebrates with legs?
Options:
- (A) Birds
- (B) mammals
- (C) Snakes
- (D) ducks
- (E) Lizards
- (F) ants
- (G) long
- (H) toads
CoT: Birds are endothermic tetrapod vertebrates. Legs define Tetrapods. Birds are endothermic vertebrates with legs.

Ans: (B)
Question: What can happen during the reproduction process?
Options:
- (A) tree falls
- (B) Mutations
- (C) Plants growth
- (D) movement
- (E) competition
- (F) adding heat
- (G) contamination
- (H) Dehydration
CoT: Reproduction is the process by which organisms give rise to offspring. Mutations are sources of variations in offspring. Mutations can occur during the reproduction process.

Ans: (B)
Question: Running water is able to do what to minerals and oxygen?
Options:
- (A) evaporation
- (B) dissolve them
- (C) reducing acid rain
- (D) recycling
- (E) clean them
- (F) separate them
- (G) hydration
- (H) cool them
CoT: Running water is better able to dissolve oxygen and nutrients than standing water. Mineral nutrients are interrelated. Running water is better able to dissolve oxygen and minerals than standing water.