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.
Payroll Taxability. Determine the Taxability of Specific Payroll Features. If you are not sure of the taxability of a specific feature, you're in the right place! *501 (c), which is non-taxable, is included in Box 1 of the W-2. The employee must deduct the amount when filing Form 1040.