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 addition to 401(k) plans, there is another defined contribution workplace retirement plan referred to as a profit sharing plan. A company can even offer a regular 401(k) and a profit sharing plan on top of that. Like 401(k) plans, profit sharing plans are employer-sponsored retirement plans that are subject to federal laws and protections.