Honors Biology Unit Two Test

Tonicity

Describes how an extracellular solution can change the volume of a cell by affecting osmosis.

Hypotonic solution

A solution that causes a cell to swell due to water moving into the cell.

Hypertonic solution

A solution that causes a cell to shrink due to water moving out of the cell.

Osmolarity

The total solute concentration of a solution.

Iso-

Prefix meaning same; water moves in and out of the cell.

Hypo-

Prefix meaning less; water moves into the cell.

Hyper-

Prefix meaning more; water moves out of the cell.

Simple diffusion

Movement of small, uncharged molecules across a membrane from an area of high concentration to low concentration; a passive transport process that does not require energy.

Concentration gradient

A space in which there is a range of concentrations of a single substance.

Facilitated diffusion

Movement of large and/or charged molecules across a cell membrane using a protein channel, from high to low concentration; a passive transport process that does not require energy.

Osmosis

Movement of water across semi-permeable membranes from high to low concentration; a passive transport process that does not require energy.

Active transport

Movement of molecules across a cell membrane against the concentration gradient, from low to high concentration; an active transport process that requires energy.

Dynamic equilibrium

Lack of concentration gradient in which there is no net movement of a substance.

Homeostasis

The state in which cells maintain stable internal conditions to independently perform their processes.

Concentration gradients

Potential energy that decreases as the gradient fades away.

Non-polar and hydrophobic molecules

Can pass easily through the cell membrane because the phospholipid’s tails are also non-polar and hydrophobic.

High surface area-to-volume ratio

A characteristic that allows cells to be small, enhancing their efficiency.

Flexible and dynamic cell membrane

A property of the cell membrane that allows it to adapt and move, ensuring that components can work together.