Vitamin A is a relatively small, lipid-soluble molecule that can behave as a hormone. Most likely its receptor A. is an ion channel receptor
B. is a protein kinase receptor
C. involves a G protein
D. is not connected to the plasma membrane
E. does not exist; vitamin A does not have a receptor

Keeping in mind the life cycle of bacteriophages, consider the following problem: during the reproductive cycle of a temperate bacteriophage, the viral dna inserts into the bacterial chromosome where the resultant prophage behaves much like a trojan horse. it can remain quiescent, or it can become lytic and initiate a burst of progeny viruses. several operons maintain the prophage state by interacting with a repressor that keeps the lytic cycle in check. insults (ultraviolet light, for example) to the bacterial cell lead to a partial breakdown of the repressor, which in turn causes the production of enzymes involved in the lytic cycle. as stated in this simple form, would you consider this system of regulation to be operating under positive or negative control?

Which of the following was not a major animal on land during the carboniferous period? amphibians insects both a and b none of the above

Compare and contrast your sells take in oxygen, water, and food. what is one waste product that leaves your cells?