In the Gram stain, crystal violet is the:
A. Decolorizer
b. Primary stain
c. Mordant
d. Counterstain
Ans: b. Primary stain
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Which of the following statements about the epicotyl is true?
A. It remains in the ground after a seed has germinated. B. It is the portion of the stem axis that is directly below the cotyledons. C. The shoot apical meristem of a seedling is located just above it. D. It takes up most of the volume within a monocot or dicot seed. E. It forms immediately above the secondary roots of a seedling.
Individuals heterozygous for the RB+ and RB? alleles can develop tumors as a result of (Select all that apply.)
A) a mitotic crossover that leads to homozygosity for RB+ in some cells and RB? in other cells. B) a somatic mutation in the RB+ allele that leads to homozygosity for RB?. C) a somatic mutation in the RB? allele that leads to homozygosity for RB+. D) the fact that RB? is dominant to RB+.
Some animal species found in caves have tiny, nonfunctional eyes. These are best described as
A) mutations. B) analogous structures. C) homologous structures. D) vestigial structures.
lacI–d mutations
a. can inactivate the repressor even if only one of the four subunits is mutant. b. occur in the region of the gene encoding the inducer binding site. c. are cis-acting. d. can only inactivate the repressor if all four subunits are mutant. e. result in the lac operon being permanently repressed.