Movement of substances

Question 1

What is diffusion

Answer 1

Diffusion is the net movement of particles from a region of higher concentration to a region of lower concentration

Question 2

What are the factors affecting diffusion

Answer 2

1. Concentration gradient
2. Diffusion distance
3. Surface area-to-volume ratio

Question 3

How does the concentration gradient affect diffusion

Answer 3

The steeper the concentration gradient, the greater the rate of diffusion

Question 4

How does diffusion distance affect diffusion

Answer 4

The shorter the diffusion distance, the greater the rate of diffusion

Question 5

How does surface area-to-volume ratio affect diffusion

Answer 5

The greater the surface area-to-volume ratio, the greater the rate of diffusion

Question 6

What is osmosis

Answer 6

The net movement of water molecules from a region of higher water potential to a region of lower water potential through a partially permeable membrane

Question 7

What is active transport

Answer 7

The process in which cellular energy is used to move the particles of a substance across a membrane against its concentration gradient

Question 8

Differences of diffusion and active transport

Answer 8

1. Diffusion is down a concentration gradient while active transport is against a concentration gradient
2. Diffusion does not require energy from respiration while active transport requires energy from active transport
3. Diffusion does not require a cell membrane while active transport requires a cell membrane

Question 9

One example of active transport

Answer 9

Dissolved mineral salts are taken up by root hair cells via active transport

Question 10

Plant cell put in a solution of higher water potential

Answer 10

1. Cell sap has lower potential than surrounding solution
2. water molecules enter via osmosis
3. Cell expands and become turgid
4. The cell wall prevents the cell from bursting

Question 11

Plant cell put in a solution of lower water potential

Answer 11

1. Cell sap has higher water potential than surrounding solution
2. Water molecules exit the cell via osmosis
3. The cell becomes flaccid
4. The cytoplasm shrinks away from the cell wall and the cell becomes plasmolysed