Diffusion, Osmosis and Active Transport 4.1.3.1-3

Question 1

What is diffusion?

Answer 1

The movement of a substance from high concentration to low concentration

Question 2

How can you increase the rate of diffusion?

Answer 2

• greater difference in concentration
• increase temperature
• greater surface area

Question 3

What is osmosis?

Answer 3

The movement of water across a partially permeable membrane from high to low water concentration

Question 4

What is active transport?

Answer 4

When substances are absorbed against the concentration gradient. It requires ENERGY from respiration

Question 5

What is an example of active transport?

Answer 5

Mineral ions taken up into plants through root hair cell

Question 6

What is an example of diffusion?

Answer 6

Gas exchange in the lungs

Question 7

Osmosis RPA method

Answer 7

1. Cut potato into six 10cm lengths
2. Find the mass of each potato piece
3. Place 1 potato pieces in 0.0, 0.2,0.4,0.6,0.8,1.0 M solutions
4. Start a stopwatch
5. After 20mins, dry potato with a paper towel and find the mass
6. Calculate percentage change in mass
7. Construct a graph

Question 8

What is the independent variable in the osmosis RPA?

Answer 8

Concentration of the solution

Question 9

What is the dependent variable in the osmosis RPA?

Answer 9

The mass of the potato piece

Question 10

What are the control variable in the osmosis RPA?

Answer 10

Volume of solution
Type of potato 
Surface area
Time 
Temperature

Question 11

How can you increase the reliability of the osmosis RPA?

Answer 11

Repeat

Calculate mean

Question 12

What are some adaptations of exchange surfaces?

Answer 12

Thin
Large surface area
Good blood supply
Moist