Diffusion, Osmosis and Active Transport

Question 1

Diffusion definition
https://www.bbc.co.uk/bitesize/guides/zc9tyrd/revision/5

Answer 1

The net movement of particles from an area of high concentration to an area of low concentration

Question 2

Factors that affect the rate of diffusion:

Answer 2

Concentration Gradient - difference in concentrations
Surface Area : Volume Ratio (S.A: Vol. Ratio)
Temperature
Distance

Question 3

Factors that speed up the rate of diffusion:

Answer 3

Steep concentration gradient - high difference in concentrations
Large surface area : Volume Ratio
High temperature
Short Distance

Question 4

Osmosis Definition

Answer 4

The movement of water particles from an area of high water potential (concentration) to an area of low water potential (concentration) through a partially/selectively permeable membrane

Question 5

Active Transport Definition

Answer 5

Active transport is the movement of particles from an area of low concentration to an area of high concentration across a partially/selectively permeable cell membrane

Particles move against the concentration gradient - using energy released during respiration

Question 6

Active Transport - biological examples

Answer 6

Uptake of nitrate ions from soil water by root hair cells in plants
Uptake of Glucose by epithelial cells in the villi of the small intestine

Question 7

Active Transport

Answer 7

Requires energy - from mitochondria

Carrier proteins (in cell membrane) pick up specific molecules and take particles through the cell membrane against the concentration gradient