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
You might also like to view...
The purpose of the fermentation process is the
A) regeneration of NAD+. B) generation of additional energy in the form of ATP. C) generation of additional reducing equivalents. D) production of novel compounds, such as inorganic acids. E) all of the above
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
a. homozygous dominant. b. heterozygous. c. heterozygous dominant. d. homozygous recessive. e. heterozygous recessive.
________ genes code for transcription factors that regulate the transcription of other genes
Fill in the blank(s) with correct word