Predation is the only form of competition among organisms in an ecological system

Which of the following substances is not involved in the chemical reaction that pro- duces smog? a. sunlight b. particulate matter c. automotive exhaust d. ozone

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?

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?