The German physician Robert Koch provided evidence to support the germ theory of infectious disease. Koch isolated bacteria from a cow with anthrax then injected the bacteria into a healthy mouse. To support germ theory, what must have happened to the healthy mouse? A: it became sick.
B: it spread smallpox.
C: it produced antibiotics.
D: it became immune to viral infections.​

Dna is colied into chromosomes in a cell

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?

The distant ancestors of tigers may have had bodies without stripes. use the theory of natural selection to explain how tigers may have evolved to have stripes.