Human activity can affect ecosystems by removing producers, consumers, and decomposers. What limiting factors may result from human actions, and what effects might they have on the flow of energy and matter in an ecosystem?

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?

In "the man in the water," what was the remarkable occurrence that rosenblatt reported?

Ascientific idea becomes valid when it is what?