Classify the following as either a specific or a nonspecific defense of the body's immune system.

• skin
• macrophages
• bacteria • mucous
• fever
• b cells • t cells
• antibodies

Average annual precipitation and are the two major features that define the biomes on earth.

Rotenone is an insecticide that is toxic

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?