The HIV virus attaches to the ________, and is thus taken into certain immune cells.
A. receptor protein CD4
B. flagellum
C. glycocalyx
D. marker proteins type A or B on red blood cells
Answer: A
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In the hypothesis that C. stellatus (a species of barnacle) is competitively excluded from the lower intertidal zone by B. balanoides (another species of barnacle), what could be concluded about the two species?
A) The fundamental and realized niches of B. balanoides and C. stellatus are identical. B) The fundamental and realized niches of B. balanoides and C. stellatus are different. C) The fundamental and realized niches of B. balanoides are different, but the fundamental and realized niches of C. stellatus are identical. D) The fundamental and realized niches of B. balanoides are identical, but the fundamental and realized niches of C. stellatus are different.
Coralline red algae have an outer covering made of:
a. cellulose. b. calcium carbonate. c. silica. d. protein. e. starch
All of the following can contribute to desertification
EXCEPT a. drought. b. overplowing. c. overgrazing. d. natural fertilizer. e. all of these.
Molecules pass in and out of the nucleus through openings in the nuclear membrane called nuclear ________
Fill in the blank(s) with correct word