During the Cambrian, reefs were built by _____, but these communities were wiped out by a mass extinction about _____ million years ago
A. calcified sponges; 515
B. bacteria; 515
C. calcified sponges; 600
D. bacteria; 300
E. calcified sponges; 300
A
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All of the following are mechanisms or adaptations of organisms to the arrival of colder
winter temperatures EXCEPT
a. hibernation. b. reduction in metabolic rates. c. migration. d. growth.
The resulting cell from the union of a male animal sex cell and a female animal sex called is called a(n)
A. gamete. B. morula. C. polar body. D. zygote. E. oogonium.
Nine (orders/families/classes) represent the highest level of taxonomic rank used in classifying viruses.
Fill in the blank(s) with the appropriate word(s).
Antigen exposure is necessary to stimulate B cells to
a. produce soluble antibodies. b. differentiate to plasma cells. c. induce genetic hypermutation in B cells. d. do all of the above.