Contractile vacuoles are
A. used to bring solutes into a cell.
B. important to certain organisms in hypertonic environments.
C. used to expel excess water from cells.
D. found in bacterial cells.
E. protein carriers in cell membranes.
Answer: C
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Being born with extra fingers on a hand is called polydactyly. This is more common in some populations in North America than others due to ____.
A. natural selection in favor of extra fingers in these populations B. random mating with other populations in North America C. an increase in mutation rate in these populations D. a founder effect because their ancestors from Europe carried the alleles E. migration of people with multiple fingers out of the population
Radula modification allowed all of the following functions in gastropods except
A. scraping algae off rocks. B. eating vegetation. C. boring holes in other mollusk shells. D. protecting themselves with nematocysts. E. injecting poison through a harpoon-like structure.
Species of Rhizobium and Bradyrhizobium bacteria are most directly associated with
a. nitrification. b. ammonification. c. nitrogen cycling. d. nitrogen fixation. e. nitrogen assimilation.
Which cells are important elements that comprise cell-mediated immunity?
A) B cells B) cytotoxic T cells C) plasma cells D) complement proteins