Diffusion

Question 1

DEFINITION

Answer 1

diffusion is the NET movement of a substance from an area of HIGH concentration to an area of LOW concentration, across a PARTIALLY PERMEABLE MEMBRANE.

Question 2

KEY POINT

Answer 2

Diffusion is a PASSIVE process, meaning it does NOT require ENERGY.

Question 3

KEY POINT

Answer 3

Molecules move around RANDOMLY, but their net movement will be from HIGH to LOW concentration until an EQUILIBRIUM is reached.

Question 4

KEY POINT

Answer 4

This movement occurs across a PARTIALLY PERMEABLE MEMBRANE.

Question 5

FACTORS EFFECTING: TEMPERATURE

Answer 5

As temperature increases the rate of diffusion also INCREASES. Molecules gain more ENERGY and move around FASTER. As a result more of the molecules move DOWN the concentration GRADIENT in a given TIME.

Question 6

FACTORS EFFECTING: SURFACE AREA

Answer 6

The LARGER the surface area, the FASTER the rate of diffusion. In our bodies structures such as the ALVEOLI in the LUNGS and the VILLI in the SMALL INTESTINE help increase the diffusion of OXYGEN and digested FOOD respectively.

Question 7

FACTORS EFFECTING: CONCENTRATION GRADIENT

Answer 7

The STEEPER the concentration gradient, the faster the rate diffusion will take place. The BIGGER the DIFFERENCE in the CONCENTRATION of the substance across the PARTIALLY PERMEABLE MEMBRANE, the FASTER diffusion will take place.

Question 8

FACTORS EFFECTING: DIFFUSION DISTANCE

Answer 8

The SHORTER the difusion distance, the FASTER the rate of diffusion will be. Many diffusion surfaces in our body are relatively THIN in order to allow diffusion to take place as EFFICIENTLY as possible.