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.
Profit Sharing. A plan by which an employer distributes a set percentage of the company's profits to its employees. Employers may distribute the portion of its profits immediately (that is, employees may receive what amounts to a bonus) or it may set up a series of accounts for employees and defer the profit sharing until employees retire.