The Precambrian-Cambrian boundary represents the first appearance of:
a. vertebrates.
b. amphibians.
c. reptiles.
d. animals with skeletons.
e. animals with soft bodies.
D
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a. True b. False Indicate whether the statement is true or false
What is true about unanchored sand dunes?
A. Wind erosion occurs on the leeward slope. B. Wind deposits sand on the leeward slope. C. Dunes move against the direction of wind. D. Wind erosion forms the dune’s slip face. E. Wind deposits constantly change dune shape.
Calculate the change in sea level (in km) if the ice sheets melted, and
write your result below (see sidebar). What will be an ideal response?
One of the general concerns about the widespread use of transgenic organisms is the
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