40. The validity of scientific theories and laws depends on evidence. Which of the following
statements of evidence supports a law rather than a theory?
A. Electrons orbit the nucleus of an atom within a certain radius.
B. DNA analysis reveals that a modern species is related to an extinct species.
C. Seafloor spreading occurs at a rate of three centimeters per year in the mid-Atlantic.
D. The amount of matter in a closed system is the same at the start of a reaction as at the end of
the reaction.

One group of reptiles, characterized by the fossil ark metal x

Which of these resources is used worldwide to make construction products, pottery, and porcelain

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?