Active/Passive/Facilitated Transport & Diffusion

Question 1

Define Active Transport

Answer 1

A form of solute transport in which the solute is move against its concentration gradient, requiring energy in the form of ATP

Question 2

What are the two types of Passive Transport, and what is the difference between them?

Answer 2

1. Diffusion:

Occurs when a solute or fluid moves across a membrane - which is freely permeable to the fluid/solute in question - across its concentration gradient

e. g. O2 & CO2 in the Alveoli
2. Facilitated Diffusion:

Occurs when a solute or fluid moves across a membrane - which is only permeable to the fluid/solute with the aid of carrier protein channels - across its concentration gradient

e.g. Osmosis in and out of a cell requires the use of aquaporins to traverse the phospholipid bilayer

Question 3

What is the difference between Primary and Secondary Active Transport?

Answer 3

Primary

Energy released by the hydrolysis of ATP drives solute movement against its concentration gradient

e.g. Na+K+ ATPase

Secondary

The movement of solute A across its concentration gradient provides the energy for solute B to be transported against its concentration gradient

e.g. Glucose and NA+ in the intestinal lumen

Question 4

Name and label the three different types of carrier protien found in membranes

Answer 4

1. Uniporter
2. Symporter
3. Antiporter