How does removing trees affect nitrogen cycling in a forest ecosystem? a. after clearcutting, more soil nitrogen was exported via runoff, ultimately accumulating in the lake. b. after clearcutting, plant uptake stopped and nitrogen accumulated in the soil. c. after clearcutting, plant uptake stopped but denitrification increased, limiting the flow of nitrogen from the soil to the lake. d. clearcutting does not appear to affect nitrogen cycling; only acid rain does.

The earth consists of a variety of different organisms. despite their diversity, however, some similarities on the structural and metabolic levels may be seen. these similarities can be attributed to a. similarities among organisms in their proteins and nucleic acids. b. the ability of organisms to readily adapt to sudden environmental changes. c. similarities in organisms' habitats and niches. d. the ability of all organisms to interbreed and produce new species.

Based on anatomical similarities, to which modern animal is dr. digger’s creature most closely related?

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?