Which of the following is the strongest evidence that cytokinins regulate cell divisions? There is _____
A) an increase of cyclin gene expression in tissues exposed to cytokinin
B) a decrease of cyclin gene expression in tissues exposed to cytokinin
C) an induction of shoot growths in tissues exposed to cytokinin
D) an induction of root growths in tissues exposed to cytokinin
E) an ability of cytokinin to interact with auxin at the molecular level and change auxin biosynthesis and transport
Answer: A
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A. pseudogenes. B. clones. C. exons. D. introns.
In invertebrates, the hairs of taste receptors ____, while those of smell receptors ____
a. directly contact the stimulus; indirectly contact the stimulus b. are derived from microvilli and contain microfilaments; are derived from cilia and contain microtubules c. transmit signals to the temporal lobes; transmit signals to the parietal lobes d. perceive taste and pain stimuli; perceive odors and taste stimuli e. detect airborne molecules; function as chemoreceptors
Replication of DNA
1.produces RNA molecules. 2.produces only new DNA. 3.produces two molecules, each half-new and half-old DNA joined lengthwise to each other. 4.generates excessive DNA, which eventually causes the nucleus to divide. 5.is too complex to characterize.
Water is able to cross plant plasma membranes by a combination of
A. diffusion and phloem. B. root pressure and turgidity. C. transpiration and Casparian strips. D. osmosis and aquaporins. E. evaporation and diffusion.