Which characteristic makes osmosis different from diffusion? 1. Osmosis requires facilitation by an energy-carrying molecule, such as ATP. Diffusion requires no additional energy to move molecules across the concentration gradient. 2. Osmosis is used for gases, such as oxygen and carbon dioxide. Diffusion is used for water that contains salt or sugar molecules. Net movement in osmosis is from areas of higher water concentration to areas of lower water concentration. 3. Net movement in diffusion occurs from areas of higher solute concentration to areas of lower solute concentration. 4. Osmosis occurs through a permeable membrane. Diffusion must occur through a semipermeable membrane.

To answer this question, researchers studied populations of the dusky salamander (desmognathus ochrophaeus) living on different mountain ranges in the southern appalachian mountains. the researchers tested the reproductive isolation of pairs of salamander populations by leaving one male and one female together and later checking the females for the presence of sperm. four mating combinations were tested for each pair of populations (a and b)—two within the same population (female a with male a and female b with male b) and two between populations (female a with male b and female b with male a). the proportion of successful matings for each mating combination was measured. for example, when all the matings of a particular combination were successful, the researchers gave it a value of 1; when none of the matings were successful, they gave it a value of 0. then the researchers calculated an index of reproductive isolation that ranged from 0 (no isolation) to 2 (full isolation). the reproductive isolation value for two populations is the sum of the proportion of successful matings of each type within populations (aa + bb) minus the sum of the proportion of successful matings of each type between populations (ab + ba). the table provides data for the geographic distances and reproductive isolation values for 27 pairs of dusky salamander populations.