An animal which may have one or two hearts to pump blood is:
Options:
- (A) squid
- (B) goats
- (C) bats
- (D) mammals
- (E) toads
- (F) Birds
- (G) edible
- (H) a fish
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Let's think first: Mollusks have a circulatory system with one or two hearts that pump blood. Interestingly, a squid is also a mollusk. Squid have a circulatory system with one or two hearts that pump blood.... So the answer is [(A)]

What learns to behave through playing?
Options:
- (A) otters
- (B) bacteria
- (C) viruses
- (D) rocks
- (E) lions
- (F) animals
- (G) humans
- (H) Birds
--
Let's think first: Playing is just one of many ways that mammals and other animals learn how to behave. Mammals include lions, bears, dogs, horses, cattle and antelopes. Playing is one way that lions learn how to behave.... So the answer is [(E)]

Aggression is behavior that is intentionally what?
Options:
- (A) friendly
- (B) complex
- (C) loud
- (D) made
- (E) negative
- (F) quiet
- (G) abusive
- (H) kicked
--
Let's think first: Aggression is behavior that is intended to cause harm or pain. Abuse means causing intentional pain or harm. Aggression is behavior that is intentionally abusive.... So the answer is [(G)]

What kind of worm belongs to the phylum platyhelminthes?
Options:
- (A) homogenous
- (B) moves
- (C) dangerous
- (D) insects
- (E) tapeworm
- (F) parasites
- (G) white
- (H) graptolites
--
Let's think first: Flatworms belong to the phylum Platyhelminthes. Flatworms Flatworms or Platyhelminthes include flukes, tapeworms, and turbellarians. Tapeworms belong to the phylum Platyhelminthes.... So the answer is [(E)]

What keeps mammals warm?
Options:
- (A) evaporation
- (B) Animal fur
- (C) staying warm
- (D) sweating
- (E) They have thick fur
- (F) with their fur
- (G) a layer of fat
- (H) Veins and arteries.
--
Let's think first: Mammals have a layer of fat under the skin to help insulate the body. Glass insulation keeps beverage warm for hours. Mammals have a layer of fat under the skin to keep them warm.... So the answer is [(G)]

The sun contributes what to ecosystems?
Options:
- (A) sun spot
- (B) energy
- (C) darkness
- (D) seeds
- (E) positive
- (F) photons
- (G) Nutrients
- (H) Energy.
--
Let's think first: Energy enters ecosystems in the form of sunlight or chemical compounds. If there is sun, there is sunlight, there is day. Energy enters ecosystems from the sun.... So the answer is [(B)]