True/false
Sometimes extinction can have a very large impact on an ecosystem. Such
important species are called keystone species.
True/false
Sometimes species are closely linked to another species. When one goes, the
other one that depended on it goes as well -w just like dominoes knocking each
other over. This is known as “domino extinction."

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?