What percentage of the species that have ever existed on earth are probably now extinct?
a. less than 10%
b. about 99.9%
c. about half
d. 25%
e. 75%
B
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A calorie is the commonly used unit of chemical energy. It is also the unit of
A. light. B. magnetism. C. sound. D. heat. E. radioactivity.
One of the ways in which the smooth muscle contractions of the digestive tract are controlled is by
A. mass movements. B. the nervous system. C. propulsion. D. peristalsis. E. chyme secretion.
In tuberculosis, when a caseous lesion calcifies, it is called a ________.
A. tubercle B. tuberculous cavity C. Ghon complex D. All of the choices are correct.
Facilitated diffusion is specific. This means ____
a. a specific protein will transport certain polar or charged molecules but not others b. that only one specific integral protein per membrane is involved in facilitated diffusion c. that the energy molecule ATP is specifically required for transport d. only specific hydrophobic molecules can be transported e. that transport of molecules occurs only in specific cells