(question). 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
(answer). 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.
The answer is (A)

(question). Neurons are the structural and functional units of where what is critical?
Options:
- (A) organs
- (B) Glial cells
- (C) nerves
- (D) Structural units
- (E) voltage
- (F) Storage units
- (G) Critical care
- (H) A computer
(answer). Neurons are the structural and functional units of the nervous system. Glial cells perform critical functions in the nervous system. Neurons are the structural and functional units of where the glial cells perform critical functions.
The answer is (B)

(question). _ is found in most molecules.
Options:
- (A) glucose
- (B) Gold
- (C) Energy
- (D) food
- (E) Polonium
- (F) Nitrogen
- (G) Helium
- (H) heat energy
(answer). Nitrogen is found in proteins, nucleic acids, and chlorophyll. Most molecules are proteins or nucleic acids. Nitrogen is found in most molecules.
The answer is (F)

(question). What can be reduced when a population suddenly gets much smaller?
Options:
- (A) Pollution
- (B) The size of the Earth
- (C) Greenhouse gasses
- (D) The size of bottlenecks
- (E) The size of the environment
- (F) Genetic variation
- (G) Plant growth is reduced
- (H) Quality of life
(answer).
Bottleneck effect occurs when a population suddenly gets much smaller. Genetic variation can be reduced by random genetic drift, population bottlenecks, founder effect. Genetic variation can be reduced when a population suddenly gets much smaller.
The answer is (F)