A transport mechanism that can move a substance against a concentration gradient by using cellular energy is
A) simple diffusion.
B) facilitated diffusion.
C) osmosis.
D) bulk transport.
E) active transport.
E
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Embryonic stem cells growing in a lab dish are bathed in a "cocktail" of chemicals that cause them to specialize into branching networks of single-nucleated cells that pulsate in unison. This tissue is most likely
A. epithelial tissue. B. cardiac muscle. C. skeletal muscle. D. smooth muscle.
In the diagram of a hair root shown, where is the dermal root sheath?
a) C b) D c) E d) F e) G
Two hours before major surgery is to begin, the patient experiences "jitters," an elevated heart rate and blood pressure, increased rate of breathing, cold sweats, and an urge to urinate. These symptoms are the result of
A) decreased levels of epinephrine in the blood. B) decreased activity of sympathetic centers in the hypothalamus. C) sympathetic activation. D) increased parasympathetic activity. E) all of these mechanisms.
The group of genes that codes for self-antigens is known as the ____________________
Fill in the blank(s) with correct word