ent strains of bacteria found in Lechuguilla Cave in New Mexico were tested for resistance to a variety of antibiotics. The antibiotics are grouped by color to show the similar mode of action/target they employ to kill bacteria. (A) Resistance in Gram-positive strains of bacteria; (B) Resistance in Gram-negative strains of bacteria.

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?

How energy flows through each level in this energy pyramid. is all the matter and energy from one level transferred to the next level?

19. a cell is viewed under a microscope and is found to have two nuclear envelopes and spindles that appear to be breaking apart. which phase of mitosis is the cell most likely in? a. metaphase b. prophase c. telophase d. anaphase