B2.1.1 - Diffusion

Question 1

Define diffusion

Answer 1

Spreading out of particles from high to low (concentration gradient)

Question 2

What kind of process is diffusion?

Answer 2

Passive process, meaning no energy is required

Question 3

Which kind of molecules can move across via diffusion?

Answer 3

Small molecules such as oxygen/glucose/amino acids/ water
NOT larger ones such as starch or protein

Question 4

How do single celled organisms get molecules transported in the body?

Answer 4

• can solely rely on diffusion
• this is because of a relatively large surface area to volume ratio

Question 5

How do multi cellular organisms transport molecules in the body?

Answer 5

• cannot rely on diffusion alone due to small surface to area ratio
• so they have several adaptations (alveoli - lungs/villi - small intestines/root hair cells - plants)

Question 6

Which three factors affect the rate of diffusion?

Answer 6

1) Concentration gradient
2) Temperature
3) Surface area of membrane

Question 7

How does concentration gradient affect the rate of diffusion?

Answer 7

The greater the difference in concentration, faster rate of diffusion
- this is because more particles moving down gradient than against

Question 8

How does temperature affect the rate of diffusion?

Answer 8

The greater the temperature, greater movement of particles
- faster movement of particles leads to more frequent collisions, hence a faster rate

Question 9

How does the surface area of the membrane affect the rate of diffusion?

Answer 9

The greater surface area, more space for particles to move through