Which one of the following statements about transport of nutrients in phloem is false?
a) Differences in osmotic concentration at the source and sink cause a hydrostatic pressure gradient to be formed.
b) Companion cells control the rate and direction of movement of phloem sap.
c) A sink may be located anywhere in the plant.
d) A sink is that part of the plant where a particular solute is consumed or stored.
e) Solute particles can be actively transported into phloem at the source.
Ans: b) Companion cells control the rate and direction of movement of phloem sap.
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Short hair (L) is dominant to long hair (l). If a shorthaired
animal of unknown origin is crossed with a long-haired animal and they produce one long-haired and one short-haired offspring, this indicates that a. the short-haired animal is pure-breeding. b. the short-haired animal is not pure-breeding. c. the long-haired animal is not pure-breeding. d. the long-haired animal is pure-breeding. e. none of these can be determined with two offspring.
Water moves across the plasma membrane into or out of a cell by osmosis when
A) there is an equal solute concentration on both sides of the membrane. B) water diffuses through a semipermeable membrane toward a higher solute concentration. C) water diffuses through a semipermeable membrane toward a lower solute concentration. D) a high solute concentration opens an aquaporin channel. E) ATP hydrolysis drives aquaporin transport.
Which feature is found in all cells?
a. nucleus containing DNA b. plasma membrane composed of phospholipids c. flagella d. cell wall composed of cellulose e. nucleoid region that contains DNA
What encodes the toxin paramecin in Paramecia aurelia?
A. mtDNA B. cpDNA C. Nuclear DNA D. Kappa particles