Which of the following is the organ for maternal-embryo exchange?
a. yolk sac
b. amnion
c. chorion
d. allantois
e. placenta
ANSWER: e
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Localized areas of destruction occurring on plants that have been infected by a virus are referred to as ________ lesions.
Fill in the blank(s) with the appropriate word(s).
Miller’s reaction chamber contained gases intended
to simulate the atmosphere of the ancient Earth. Which of the following gases was NOT included? a. carbon dioxide b. methane c. ammonia d. water vapor e. hydrogen gas
The progression from metaphase to anaphase is triggered by
a. activation of protein kinases by MPF. b. ubiquitin-mediated proteolysis of key proteins. c. binding of an inhibitory protein to MPF. d. depolymerization of the mitotic spindle.
The stage of disease that is characterized by early, mild symptoms is called the
A) period of illness B) incubation period C) prodromal period D) period of convalescence