Diffusion Across a Cell Membrane. Diffusion is the movement of a substance across a membrane. Substances diffuse across cell membranes in a process known as passive transport. This means that the cell does not expend any energy in transporting substances across the cell membrane. Instead, substances move down their concentration gradient as a result of random thermal motion.
401k and profit sharing plans are both forms of retirement plans. They allow employees to make pre-tax contributions to an account where contributions and earnings are not taxed until distributed. Some 401k plans require an employer to make contributions to a plan.
In a standard allocation, each would receive $3,000. Under the age-weighted profit sharing plan, the allocation could be $5,673 for the older and $327 for the younger--seventeen times as much if the plan is not subject to the top-heavy rules, and six times as much if it is ($5,100 and $900). Example 2.