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 profit-sharing plan is a type of defined contribution retirement plan that employers may establish for their workers. The employer may add up to the annual limit to each employee's profit-sharing account in any year the company has a profit to share, though there is no obligation to make a contribution in any year.