Fossil tooth parts of extinct ____ suggest that these organisms were the earliest vertebrates with bonelike structures
a. acanthodians
b. conodonts
c. osteolepiforms
d. placoderms
e. ostracoderms
ANSWER: b
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Trypan blue is
(a) taken up by living cells. (b) taken up by dead cells. (c) taken up by both living and dead cells. (d) used to identify plant cells.
Which gas is increasing in the atmosphere and
intensifying the greenhouse effect? a. carbon dioxide b. carbon monoxide c. ozone d. nitrogen e. oxygen
The structure labeled A in Figure 27-1 is a:
a. gametangium of an alga.
b. gametangium of a plant.
c. germinating spore.
d. megasporangium of an alga.
e. megasporangium of a plant.
What is the route of water in the water vascular system of a starfish?
A. Water enters the ampullae and then goes to the tube feet and from thence to the radial canals, then the ring canal, and finally exits through the madreporite. B. Water enters the madreporite into the radial canals and from thence into the ring canal, then the ampullae and finally into the tube feet. C. Water enters through the madreporite into the ring canal and from thence into the radial canals to the ampullae and finally into the tube feet. D. Water enters the ring canal, then goes into the radial canals, and finally through the madreporite to the ampullae and tube feet. E. Water enters the madreporite into the ampullae and from thence into the ring canal, then the radial canals to the ampullae and finally into the tube feet.