Topic 3: Movement in and out cells

Question 1

Active transport

Answer 1

The movement of substances from a low concentration to a higher concentration (against the concentration gradient) across a membrane, with the use of energy from respiration.

Question 2

Concentration gradient

Answer 2

The difference in concentration between two areas. The greater the concentration gradient, the faster the rate of diffusion.

Question 3

Diffusion

Answer 3

The net spreading out of particles from a high concentration to a lower concentration (down their concentration gradient). Diffusion is as a result of the kinetic energy of the random movement of particles (passive).

Question 4

Diffusion distance

Answer 4

The distance that substances must diffuse. The smaller the diffusion distance, the faster the rate of diffusion.

Question 5

Flaccid

Answer 5

Describes a plant cell that has been placed in a more concentrated solution. Water leaves the cell by osmosis. The volume decreases and the cytoplasm pulls away from the cell wall.

Question 6

Osmosis

Answer 6

The diffusion of water molecules from a region of high water concentration to a region of lower water concentration across a partially permeable membrane.

Question 7

Plasmolysis

Answer 7

The process by which the cytoplasm pulls away from the cell wall as a result of water loss from the cell.

Question 8

Surface area

Answer 8

The total area occupied by the surface of an object. The larger the surface area, the faster the rate of diffusion.

Question 9

Turgid

Answer 9

Describes a plant cell that has been placed in a more dilute solution. Water enters the cell by osmosis. The volume increases and the cytoplasm pushes against the cell wall.

Question 10

Turgor pressure

Answer 10

The pressure exerted by fluid within a cell which pushes the cell membrane against the inelastic cell wall.

Question 11

Water potential

Answer 11

A measure of the tendency of water molecules to move from one area to another.