The Paleozoic–Mesozoic boundary is a major break in the geologic time scale because
a. it is marked by a mass extinction event.
b. it is marked by an explosion in the quantity and diversity of life.
c. it is when reptiles first appeared.
d. it is when mammals first appeared.
e. it is a time of great volcanic activity.
A
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Which of the following is a characteristic of commercial agriculture?
A) Most of the production is sold to companies that process the food and sell it to consumers. B) The farmer depends on his or her own production for most food. C) Technology is low. D) A great deal of human labor goes into farming.
Hawaiian volcanoes are examples of:
a) Shield volcanoes b) Stratovolcanoes (or composite cones) c) Cinder cones (or scoria cones) d) Mud volcanoes e) Lava domes
The prevailing westerlies are more consistent than the easterlies
Indicate whether the statement is true or false
A vector is an organism that ________
A) a host species vulnerable to infection B) carries a parasite but is never affected by it C) preys upon vulnerable species D) is beneficial to parasitized organisms E) is always parasitic