Describe two processes through which rare alleles might become more frequent in a population

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.

passive transport is a movement of biochemicals and other atomic or molecular substances across cell membranes without need of energy input. unlike active transport, it does not require an input of cellular energy because it is instead driven by the tendency of the system to grow in entropy.

so, according to what that says, i believe it's hypertonic and hypotonic.

good luck!