What are TWO factors that could affect the rate of diffusion?

Diffusion occurs when particles move from an area of high concentration to an area of low concentration. The factors affecting rate of diffusion are: concentration, temperature, mass of the particle and properties of the solvent in which diffusion occurs. Faster movement equals faster diffusion.

Explanation:

Several factors affect the rate of diffusion of a solute including the mass of the solute, the temperature of the environment, the solvent density, and the distance traveled. The rate of diffusion is affected by the concentration gradient, membrane permeability, temperature, and pressure. Diffusion takes place as long as there is a difference between the concentrations of a substance across a barrier.

Explanation:

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).