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.
An arrangement in which an employer shares some of its profits with its employees. The compensation can be stocks, bonds, or cash, and can be immediate or deferred until retirement. Profit-sharing allows for changing contributions each year. Contributions are determined by a formula to allocate the overall contribution and distribution of accumulated funds after the retirement age. Unless the plans are defined as an elective deferral plan, the contributions are not tax deductible.