A graduate student is studying the distribution of auxin in roots and stems exposed to sunlight
He notices that more auxin collects in the sides of stems and roots that are not
exposed to light; however, the effects of this distribution are very different. Why? Select all
correct choices.
A. Auxin prevents cell elongation in the
shaded cells of stems.
B. Auxin (via ethylene) promotes cell
elongation in the shaded cells of roots.
C. Auxin (via ethylene) prevents cell
elongation in the shaded cells of roots.
D. Auxin promotes cell elongation in the
shaded cells of stems.
C,D
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Which one of the following statements about intracellular transport is true?
A. Microtubules and microfilaments facilitate cellular movement, but intermediate filaments do not. B. Microtubules and intermediate filaments facilitate cellular movement, but microfilaments do not. C. Intermediate filaments and microfilaments facilitate cellular movement, but microtubules do not. D. Intermediate filaments, microfilaments, and microtubules all facilitate cellular movement of one kind or another.
Which of the following probabilities is correct regarding a mating of an Ss RR individual to an individual who is Ss Rr ? (A – indicates the the second allele is either dominant or recessive.)
A) S– RR: 37.5% B) Homozygous recessive: 10% C) Heterozygous both alleles: 50% D) ss R– : 15.5%
A negative feedback system is designed to set off mechanisms that will:a
lower the abnormal value until it reaches its normal level. b. increase the abnormal value until it reaches normal levels. c. return the system to steady-state levels. d. speed up the body's response until it reaches its normal levels. e. slow down the metabolic rate until steady-state levels are reached.
Cilia and flagella of eukaryotic cells are composed of
A. nine triplets of microtubules in a circle. B. protein fibers in a helical arrangement. C. actin filaments in a 9 + 2 arrangement. D. microtubules in a 9 + 2 arrangement.