Jacque is hiking in the mountains and sees a very large and colorful rock layer. It looks different than the surrounding rock layers. What is the best way for Jacque to investigate what the environment was like when this rock layer was deposited?

Jacque could measure the height of the rock layer.

Jacque could check if the rock layer has fossils in it.

Jacque could look at the color of the surrounding rock layers.

Jacque could chip off a chunk of rock from the rock layer and smell it.

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?