When the grand canyon formed many small mammal population were divided. some members of the population were on one side and others are on the other, therefore, they were no able to mate with one another. over time this separation and inability to mate with one another led to the emergence of new species. this type of speciation is called a) sympatric speciation. b) allopatric speciation. c) parapetric speciation. d) peripatric speciation.

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?

One important development during the 3rd trimester that will insulate the infant against changes in temperature is a. the deposition of fat under the skin b. the closing of the septum between c. the atria of the heart d. the beginnings of lung functioning e. the beginnings of light and sound sensing

Which of the organisms listed below performs nitrogen fixation? a. legumes b. plants c. bacteria d. fungi