Imagine an invertebrate that lives in an estuary where salinity varies cyclically with the tides. If this individual is able to adjust the salt concentration of its body fluids, its salt concentration will have
A) slight fluctuations that are kept within a narrow range.
B) irregular fluctuations that range from large to small.
C) a cyclic fluctuation opposite that of the surrounding water.
D) a cyclic fluctuation depending upon when the animal drinks.
Answer: A
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What would enhance water uptake by a plant cell?
A) decreasing the ? of the surrounding solution B) increasing the pressure exerted by the cell wall C) the loss of solutes from the cell D) increasing the ? of the cytoplasm E) positive pressure on the surrounding solution
Sxl protein mediates differential expression of genes further downstream in the developmental pathway
In females, active Sxl protein produced from Pm leads toproduction of proteins that facilitate female developmentâfirst Tra protein, which then, with Tra-2, facilitates splicing of the mRNA for active Dsx protein. In males: A. the absence of Sxl leads to a different splicing pattern of tra transcripts; a different version of Dsx isproduced that leads to male development. B. transcription from promoter Pe results in acharacteristic splicing pattern and the production of a burst of active Sxl protein. C. only stop codons are recognized, leading to splicing of Tra and overactivity of SxI. D. the start codons are preferentially removed in splicing, causing a premature termination of Dsx translation leading to male development.
If alleles L, M, and N are on the maternal
chromosome and l, m, and n are on the paternal chromosome, the only way that a gamete from a heterozygote will produce a gamete with alleles l, m, and N is through a. nondisjunction. b. the laws of segregation. c. the law of independent assortment. d. crossing over. e. chromosome aberration.
RNA molecules that also act as enzymes are given the name
A. cofactors. B. coenzymes. C. allosteric enzymes. D. ribozymes.