During the development of the vulva in Caenorhabditis, when EGF binds an EGF receptor on a progenitor cell:
A. signal transduction results in activation of a
set of transcription factors.
B. genes that produce the Notch ligand are
transcribed.
C. genes that produce the Notch receptor are
inhibited.
D. genes that produce the EGF receptor in
the adjacent cells are inhibited.
E. All of these choices are correct.
E
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Key sequences exist within promoters, which vary somewhat among various promoters but are sufficiently constant that they can be represented by a sequence of bases most often found at each position. These representations are called ________ sequences.
A. consensus B. idealized C. convergence D. common
Leptin is a circulating hormone that is produced by fat cells and plays a role in body metabolism and obesity. It normally binds to receptors in the brain and inhibits appetite. Studies have demonstrated that when obese mice that are leptin deficient are injected with leptin they quickly lose their excess weight. Interestingly, however, many overweight people have high levels of leptin in their bloodstream. Why do you think that the high levels of leptin in obese individuals are insufficient to curb their appetite?
A. The form of leptin released by obese people may lack protein kinase activity. B. Paracrine signaling may be disrupted in obese people with high levels of leptin. C. Obese people who have high levels of leptin may have a leptin receptor with decreased sensitivity. D. In obese people with high levels of leptin, the leptin is a nonfunctional second messenger.
If the quantities of the four bases in a DNA molecule are measured, we find that
A) T = A and C = G. B) A = G and C = T. C) A = C and G = T. D) no two bases are equal in amount. E) all bases are equal in amount.
________ would help prevent the creation of leachate.
A- adding hazardous chemical to solid waste prior to landfilling B- Adding O2 to solid waste prior to landfilling C- Capping the landfill when it is filled to capacity D- Adding H2O to solid waste prior to landfilling E- Using a single-liner system rather than a double-liner system