In one kind of butterfly, brown color is caused by a dominant allele, B, and white color is caused by a recessive allele, b. The table shows the observed numbers of phenotypes in a population of 100 butterflies, Phenotype Number of individuals Brown 84 White 16 What is the frequency of the heterozygous genotype in this population of butterflies? O 0.24 0.36 0.48 60

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?