B1-Active Transport

Question 1

Active transport

Answer 1

is a method of transporting molecules or ions across a membrane against a concentration gradient moving molecules or ions from a region of low concentration to one of high concentration.

Question 2

What does active transport require?

Answer 2

energy in the form of ATP (adenosine triphosphate) and special carrier proteins in the cell membrane are needed to pump the molecules or ions.

Question 3

Examples of active transport?

Answer 3

The sodium-potassium pump in nervous impulses. Here sodium ions are pumped into the cell
The proximal convoluted tubules of the kidney. Here the process enables the re-absorption of glucose, amnio acids and sodium so that they are not excreted in urine
The movement of sugars into the phloem of plants
The absorption of mineral ions from the soil via the root hair cells of plants

Question 4

How easy the exchange of substances

Answer 4

depends on the organism’s surface area to volume ratio (SA: V ratio).
Having a thin membrane or being thin to provide a short diffusion path making it as short as possible
Maintaining a steep concentration (diffusion) gradient like animals having an efficient blood supply.
And being ventilated in animals makes gas exchange more efficient by maintaining steep concentration gradients.