Platyhelminthes, like the flatworm seen here, do not have a respiratory system. all but one of the statements explains why this is possible. that is they a) are anaerobic organisms. b) live in a moist/aquatic environment. c) have a high surface area: volume ratio. d) have a thin body that facilitates diffusion throughout.

1. variations in a population of moths allow for some of its members to be able to adapt to environmental changes. the better adapted of the moths will be able to survive the change and thus prevail as the “fittest” of the species. (a) describe three mechanisms in which variation can occur within a species population. (b) explain which mechanism or mechanisms would be responsible for the survival of a population of peppered moths better than white moths in an environment affected by industrial soot. justify your answer.

Which of the following is a common response to cell signaling?

The small molecule cyclic amp (camp) takes about 0.2 second to diffuse 10 μm, on average, in a cell. suppose that camp is produced near the plasma membrane on one end of the cell; how long will it take for this camp to diffuse through the cytosol and reach the opposite end of a very large cell, on average? assume that the cell is 200 μm in diameter.