Active Transport

Question 1

What is active transport?

Answer 1

The movement of molecules and ions across plasma membranes, usually against the conc grad requiring energy.

Question 2

Give 2 differences between active transport and facilitated diffusion?

Answer 2

1. Active transport goes up the conc grad, FD goes down.

2. Active transport requires energy, FD doesn’t

Question 3

Why is ATP important for active transport?

Answer 3

Releases energy when hydrolysed so solutes can be transported.

Question 4

What are co-transporters?

Answer 4

Type of carrier protein that bind 2 molecules at a time. The conc grad of one molecule is used to move the other molecule against own conc grad.

Question 5

How is glucose absorbed?

Answer 5

1. Na ions actively transported out of epithelial cells, into blood by sodium-potassium pump. Creating a conc grad.
2. Na ions diffuse from ileum into epithelial cell down conc grad via sodium-glucose co-transporter proteins. Co-transporter carries glucose into cell with Na. Conc of glucose in cell increases.
3. Glucose diffuses out into blood down conc gradient through protein channel by facilitated diffusion

Question 6

What factors affect rate of active transport?

Answer 6

1. Speed of carrier proteins - faster = faster rate
2. Number or carrier proteins - more = faster rate
3. Rate of respiration and availability of ATP - resp. Inhibited no active transport.