How are HIV virions rendered virulent?
A. the action of protease releases reverse transcriptase and capsomeres after the virion buds from the cell.
B. they bud to the surface of the host cell.
C. they use a chemokine receptor to remove gp120.
D. they bind to smooth muscle cells.
E. they contact the cytoplasmic membrane via gp41.
Answer: A
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The perceived pitch of a sound depends on _____
A) which part of the tympanic membrane is being vibrated by sound waves B) which part of the oval window produces waves in the cochlear fluid C) which region of the basilar membrane was set in motion D) whether or not the sound moves the incus, malleus, and stapes E) whether or not the listener has had training in music
Suppose an individual is heterozygous for alternate alleles of gene A (Aa). Under what conditions would a crossover in a somatic cell of this individual lead to a clone of cells that are homozygous for a? (Pick the most precise answer.)
A) The crossover would have to occur between the A locus and the centromere and involve two homologous (nonsister) chromatids. B) The crossover would have to occur between the A locus and the end of the chromosome and involve two homologous (nonsister) chromatids. C) The crossover would have to occur between the A locus and the end of the chromosome and involve two nonhomologous chromosomes. D) The crossover would have to occur between the A locus and the centromere and involve two sister chromatids.
If the physical expression of a heterozygous individual is intermediate between those of the homozygotes, the alleles are ________
Fill in the blank(s) with correct word
Evolution occurs:
A. only through natural selection. B. only when the environment is changing. C. only via natural selection, genetic drift, migration, or mutation. D. almost entirely because of directional selection.