Why doesn't a flatworm have a circulatory system?
a. The animal is thin enough to permit effective gas exchange by diffusion.
b. There is not enough room for a circulatory system because of the large gastrovascular
cavity.
c. The animal lacks muscles, so it could not have a heart to pump blood.
d. Only bilaterally symmetrical animals need a circulatory system.
e. Only vertebrates have circulatory systems.
A
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If plants are exposed to a toxin that makes the thylakoid membrane leaky to hydrogen ions, predict the rate of oxygen production by the plants
A. increase B. decrease C. does not change
Mammals evolved from which group in the late Triassic period?
a. diapsids b. pelycosaurs c. therapsids d. anapsids
Four of the following are members of the bony fishes. Which one is the exception?
a. teleosts b. ray-finned fish c. lungfish d. stingrays e. lobe-finned fishes
Pseudomonas is an enteric gram-negative rod.
a. true b. false