Which of the following statements about physical models is not true?
a. physical models are often three-dimensional representations.
b. physical models are used to represent an object or event.
c. physical models are usually in the form of a graph.
d. physical models can be used to depict microscopic objects

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?

Me with biology endocrine system crossword also image left i need with hw

How do living things obtain phosphorus