Which of the following is not a characteristic of the transcriptional ground state in higher eukaryotes?
A. Gene promoters are essentially inactive in the absence of regulatory proteins.
B. RNA polymerase initiates efficient transcription in the absence of repressors.
C. Access to promoters is restricted by the structure of chromatin.
D. Virtually every gene requires activation.
B
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True or False: The evolution of the amniotic egg was a significant event in the vertebrate lineage because it allowed for development in a terrestrial environment
A. true B. false
Precursor-mRNA (pre-mRNA) typically exists
a. only in prokaryotes. b. in both the nucleus and cytoplasm of eukaryotes. c. only in the cytoplasm of eukaryotes. d. in both prokaryotes and eukaryotes. e. only in the nucleus of eukaryotes.
What happens to neurons in the approach known as optogenetics?
A) Mutations to ion channel proteins are corrected. B) The neurons are made to express light-sensitive ion channels. C) Neurotransmitter stores are depleted. D) Fusion of neurotransmitter vesicles to the presynaptic membrane is blocked. E) Leakage of cytoplasmic polyanions is blocked.
The hypothesis of punctuated equilibrium was proposed by Eldredge and Gould to explain the apparent long-term genetic stability of
a. many species occupying the same niche in an ecosystem b. organisms that encounter many environmental changes c. climax communities resulting from ecological succession d. some species as evidenced by the fossil record e. certain alleles common to a wide variety of organisms