Key Words

Question 1

Diffusion

Answer 1

The net movement of molecules (or ions) from a region of high concentration to a region of low concentration. It is passive.

Question 2

Facilitated diffusion

Answer 2

Diffusion involving the presence of protein carrier molecules to allow the passive movement of substances (normally large, polar or charged molecules) across plasma membrane.

Question 3

Osmosis

Answer 3

The passage of water from a region where there is a higher water potential to a region where there is a lower water potential through a partially permeable membrane.

Question 4

Water potential

Answer 4

The pressure created by water molecules. It is the measure of the extent to which a solution gives out water. The greater the number of water molecules present, the higher (less negative) the water potential. Pure water has a water potential of zero.

Question 5

Isotonic

Answer 5

A solution which has the same water potential as the cell within it.

Question 6

Active transport

Answer 6

Movement of a substance from a region where it is in a low concentration to a region where it is in a high concentration. The process requires the expenditure of metabolic energy in the form of ATP.

Question 7

Co-transport

Answer 7

The transport of one substance coupled with the transport of another substance across a plasma membrane in the same direction through the same protein carrier.

Question 8

ADP

Answer 8

A nucleotide which combines in a condensation reaction, catalysed by ATP synthase, with a phosphate molecule to form ATP.

Question 9

ATP synthase

Answer 9

An enzyme which catalyses the formation of ATP.

Question 10

ATP hydrolase

Answer 10

An enzyme which catalyses the hydrolysis of ATP.