Part 3: Active Transport

Question 1

Define active transport

Answer 1

The movement of a substance from an area of lower concentration to an area of higher concentration (against a concentration gradient) across a membrane, using energy.

Question 2

Explain how active transport differs from both diffusion and osmosis

Answer 2

• Active transport is the movement of a substance from an area of lower concentration to an area of higher concentration, but diffusion and osmosis are the net movement of particles from an area of higher concentration to an area of lower concentration.
• Active transport moves against a concentration gradient, but diffusion and osmosis move down a concentration gradient.
• The molecules in active transport move across a partially permeable membrane, but in osmosis and diffusion they don’t

Question 3

What does the rate of Active transport depend on?

Answer 3

The rate of active transport depends on the rate of respiration.

Question 4

How do plants use active transport?

Answer 4

1.Mineral ions in the soil, such as nitrate ions, are usually found in very dilute solutions. These solutions are more dilute than the solution within the plant root hair cells. By using active transport, plants can absorb these mineral ions, even though it is against a concentration gradient.
2. Active transport allows plants root hairs to absorb mineral ions required for healthy growth from very dilute solutions in the soil against a concentration gradient.

Question 5

How do crocodiles make use of active transport?

Answer 5

Some crocodiles have special salt glands in their tongues. These remove excess salt from the body against the concentration by active transport. That’s why members of the crocodile species can live in estuaries and even in the sea.