Active Transport

What is Active transport?

It is the movement of molecules from an area of low concentration to an area of higher concentration (against a concentration gradient)through a selectively permeable membrane. Unlike diffusion and osmosis, this process requires the use of energy in the form of ATP (Adenosine Triphosphate).

Examples of Active Transport

In humans, active transport takes place during the digestion of food in the small intestine. Carbohydrates are broken down into simple sugars such as glucose. The glucose is absorbed by active transport into the villi, to be passed into the bloodstream and taken around the body. (Source: http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_pre_2011/homeostasis/importancerev6.shtml)

Active transport is also important in plants. Let us assume that a plant's root has 0.1 g of Magnesium and the soil has  0.001g of Magnesium. If diffusion was to take place (passive transport), then the plant would lose the Mg it has in it. However, because of active transport the plant can still take up more Mg although it has a higher concentration compared to the amount found in the soil. However, the plant would have to use up energy (ATP) in order to take in more Mg.

 

(Image source:  http://hyperphysics.phy-astr.gsu.edu/hbase/biology/nakpump.html)