At the end of the Permian period a large mass extinction occurred; 90-95% of the marine and terrestrial species were eliminated. What is thought to be the possible cause of this mass extinction?

A. Competition between marine and terrestrial species
B. Volcanic eruptions
C. Meteorite collisions with Earth
D. Glaciation
E. Sudden drop in atmospheric O2


Ans:
B. Volcanic eruptions
D. Glaciation

Biology & Microbiology

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In skeletal muscle contraction, which of the following undergoes a conformational change when it

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a. troponin b. Ca2+ c. tropomyosin d. ATP e. acetylcholine

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In the United States, parathion is the most widely used member of a class of ____.

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b. organophosphate insecticides
c. chlorophosphate fungicides
d. chlorophosphate herbicides
e. chlorophosphate insecticides

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The publication date of Darwin's Origin of Species was:

A) 1869. B) 1809. C) 1859. D) 1900.

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Which of the following is a biotic factor of an ecosystem?

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