Water flows into the source end of a sieve tube because _____
A) sucrose has diffused into the sieve tube, making it hypotonic
B) sucrose has been actively transported into the sieve tube, making it hypertonic
C) water pressure outside the sieve tube forces in water
D) the companion cell of a sieve tube actively pumps in water
E) sucrose has been transported out of the sieve tube by active transport
Answer: B
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Histamine
a. causes blood vessels to contract. b. causes capillaries to lose their permeability. c. causes an outward flow of fluids from the capillaries. d. reduces tissue swelling. e. enhances the function of cytokines.
The most accurate description of an organism with genotype AaBb is
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