True or false: The loop of Henle represents a countercurrent exchanger because it creates a concentration gradient rather than simply maintaining it
A. true
B. false
B
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Although similar to eukaryotic photosynthetic organisms, cyanobacteria are different because they
A. have only photosystem I not photosystem II. B. do not have any photosynthetic membranes. C. do not have chloroplasts. D. have only photosystem II not photosystem I.
Because all commercially produced energy has some kind of negative environmental impact, it is a good idea to
simply use ____.
a. wind energy b. solar energy c. less energy d. incandescent lightbulbs e. less water
Using the techniques of genetic engineering, you design a protein you want to accumulate within the ER of yeast cells. To accomplish this goal, you need to
A) do nothing; all proteins go through the ER. B) incorporate appropriate mannose-6-phosphate groups. C) incorporate the appropriate DNA sequence(s) to create signal sequences in the mature peptide. D) incorporate radioactive amino acids into the protein. E) remove the N-formyl group located at the N-terminus of the polypeptide.
What is the specific role of Xist in mammalian X-inactivation?
a. It encodes a protein that triggers heterochromatin formation on one X and suppresses it on the other X. b. It is a DNA element acting as a binding site for proteins that trigger heterochromatin formation. c. It produces an antisense RNA that prevents inactivation of one X chromosome. d. It produces an RNA that accumulates on the future inactive X. e. It encodes a transcription factor that activates genes producing proteins that function in X-inactivation.