A currently accepted hypothesis for gravitropism in plants is that:
A) sedimentation of organelles triggers hormone release.
B) bending of leaves in response to gravity triggers growth in the opposite direction.
C) microscopic eyespots trigger upward (skyward) growth.
D) ground contact inhibits stem growth while air stimulates it.
Answer: A
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Which of the following statements about RNA polymerase in bacteria is INCORRECT?
A. It binds the promoter region of a gene. B. It is bound to a sigma factor during initiation of transcription. C. It synthesizes RNA. D. It catalyzes the addition of nucleotides to the 5?end of a growing RNA strand. E. It dissociates from the DNA at the terminator.
Which group of tiny marine organisms have the simplest body and smallest genome of all modern animals?
a. sponges b. choanoflagellates c. placozoans d. cnidarians e. flatworms
In biology, a trait that arose in an ancestor and is passed along to its descendants is referred to as a...
a) molecular clock b) derived character c) taxonomic group d) physical similarity
Which statement concerning bryophyte reproductive cells is true?
A. The gametophytes are shorter-lived than the sporophyte. B. Spores and gametes are produced by mitosis. C. Their features constrain bryophyte stature. D. The gametophytes produce nonmotile sperm. E. Spores and gametes are both used for sexual reproduction.