1.2 - Active transport

Question 1

When do cells use active transport?

Answer 1

• When they need to absorb substances in short supply
• i.e against the concentration gradient
• across a partially permeable membrane

Question 2

What does active transport require?

Answer 2

The use of the energy released in respiration

Question 3

Give an example when active transport is used to absorb ions from a dilute solution

Answer 3

• Root cells absorb mineral ions
• from the dilute solutions in the soil
• by active transport

Question 4

Why is active transport required for cells to be able to absorb ions from a dilute solution?

Answer 4

They are going against the concentration gradient

Question 5

Give an example of when active transport is used to absorb a sugar

Answer 5

• Glucose
• can be reabsorbed into the kidney tubules
• by active transport

Question 6

Describe how active transport works (4)

Answer 6

• A transport protein is situated between the outside and inside of a cell
• The useful molecules attaches to the transport protein
• The transport protein rotates and releases the molecule inside the cell, using energy
• The transport protein rotates back again (often using energy)