The initiation of transcription in eukaryotes almost always requires activator proteins because:
A. RNA polymerases have little to no intrinsic affinity for promoter sequences.
B. RNA polymerases cannot synthesize RNA polymers without association with coactivators.
C. promoter sequences are almost always bound by repressor proteins.
D. eukaryotic genes exhibit very low gene density.
A
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Failure to recover a specific band in a gel made after PCR can be attributed to:
A. inappropriate annealing of primers to the DNA template. B. inappropriate design of gene specific primers. C. inappropriate numbers of cycles for amplification. D. None of the answer options are correct. E. All of the answer options are correct.
An embryo impants in the uterus when it reaches the _______ stage of development.
Fill in the blank(s) with the appropriate word(s).
Nonscientists often use the words ''name,'' ''identify,'' and ''classify'' interchangeably, as when asking ''Can you name this?'' or ''Can you identify this?'' or ''Can you classify this?'' when they simply want to know what an organism is. Which of the following is/are correct usage(s) of the term(s)?
A. Only the scientist who first describes a new species actually names it. B. Classifying is grouping, and to classify something requires several organisms so you can group one as closer to a second and distant from a third. C. A crop scout on a farm using a key to detect pest insect species is identifying insects but not naming or necessarily classifying them. D. A scientist who publishes the name and description of a new species must necessarily also know both how to identify and classify the species. E. All of the choices are correct.
Why is there natural selection for reduced parasitic bacterial genomes?
a. The parasitic lifestyle eliminates metabolism leading to gene loss. b. Parasites have reduced metabolic needs leading to gene loss. c. Parasitic bacteria are primitive and never had metabolic genes. d. Transposons have caused mutagenesis and genes have been lost.