5.4 Active Transport

Question 1

Define active transport. (3 marks)

Answer 1

The movement of molecules/ions into or out of a cell from a region of lower concentration to a region of higher concentrations. The process requires energy and carrier proteins.

Question 2

Describe active transport. (4 marks)

Answer 2

1. The molecule/ion binds to receptors in the channel if the carrier protein (on the outside of cell)
2. ATP binds to the carrier protein on the inside of the cell and is hydrolysed to ADP and Pi
3. The Pi binds to the carrier protein, and changes it’s shape so that it opens up to the inside of the cell
4. The molecule/ion is released into the cell + Pi molecules released and recombines with ADP to make ATP + Cartier protein returns to original shape.

Question 3

What is bulk transport? (1 mark)

Answer 3

A type of active transport that transports large molecules and whole cells.

Question 4

What are the two types of bulk transport? (2 marks)

Answer 4

Endocytosis
Exocytosis

Question 5

Define endocytosis. (1 mark)

Answer 5

The bulk transport of material into cells.

Question 6

Define exocytosis. (1 mark)

Answer 6

The bulk transport of material out of cells.

Question 7

Name the two types of endocytosis. (2 marks)

Answer 7

Phagocytosis
Pinocytosis

Question 8

What is phagocytosis? (2 marks)

Answer 8

The bulk transport of solids out of cells.

Question 9

What is pinocytosis? (2 marks)

Answer 9

The bulk transport of liquids out of cells.

Question 10

Describe endocytosis. (3 marks)

Answer 10

1. The cell surface membrane bends inwards when it is in contact with the materiel being transported.
2. The membrane enfolds the material until it forms a vesicle.
3. This vesicle pinches off and moves onto the cytoplasm:

Question 11

Describe exocytosis. (2 marks)

Answer 11

1. Vesicles move towards and fuse with the cell surface membrane.
2. Contents of the vesicles are released outside of the cell.