bio exam #2: osmosis & diffusion

what is a solute?

what gets dissolved (like sugar).

what is a solvent?

what does the dissolving (like water).

what is a solution?

the mix of both solute and solvent (like sugar water).

what does tonicity refer to?

how the concentration of solute in one solution compares to another, indicating which way water will move.

what does hypotonic mean?

the outside has less solute than inside the cell, resulting in water moving into the cell which can cause it to swell or burst.

what does hypertonic mean?

the outside has more solute than inside the cell, resulting in water moving out of the cell, causing it to shrink.

what is isotonic?

inside and outside have the same amount of solute, allowing water to move equally both ways, keeping the cell the same size.

what is osmosis?

the movement of water through a cell membrane from where there's more water to where there's less water.

what is brownian motion?

the random movement of tiny particles due to collisions with moving molecules, increasing with heat and slowing down with cold.

what is active transport?

when the cell uses energy to move things across its membrane, usually from low to high concentration.

what is passive transport?

when substances move across the membrane without energy, from high to low concentration.

what is dialysis?

a process where small molecules pass through a membrane while large ones cannot, functioning like a filter.

what is a paramecium?

a tiny, single-celled organism that lives in water and moves using little hairs called cilia.

what does high concentration mean?

a lot of particles in one area.

what does low concentration mean?

fewer particles in an area.

what does equal concentration mean?

both sides have the same amount of solute.

what are phospholipids?

special molecules that make up the cell membrane, having a water-loving head and a water-hating tail.

what is the fluid mosaic model?

a model describing the cell membrane as flexible ('fluid') and composed of many parts like proteins and lipids ('mosaic').

what is the plasma/cell membrane?

the thin layer surrounding the cell, controlling what goes in and out.

what is simple diffusion?

the process where small molecules move through the membrane easily, from high to low concentration, without energy.

what is facilitated diffusion?

the process where larger molecules move through protein channels in the cell membrane