how does surface area affect rate of active transport?

Question

factors affecting rate of active transport...

Answer 1

Think of it this way, if I can fit 10 active transport channels in 1 cm^2 of space then if I have 2 cm^2 of space I should be able to fit 20, right. So said another way, the more surface area available the more active transport can take place. This is why the inner lining of the intestines is full of microvilli, really tiny fingerlike projections, because that increases the surface area which allows the intestines to bring in more nutrients than it would if the lining were just flat. 

Answer 2

This is a classic question concerning the intestinal tract, particularly the small intestine b/c that is where the most absorption in the digestive system takes place (that will be a question on your test...don't put stomach).  The best way to think of this one is to remember that the more channels, the better.  And, you can only have so many channels in a one area.   So, more channels require more area (surface area).  As far as the rate, think of a sand clock (the ones from board games).  The reason they work is because you can only have so much sand fall down at each moment in time. This is why they can calibrate for an hour's time (rate).  I.e., with more holes, it would empty quicker than one hour.

Be sure to keep in mind that the term "active" means that uses energy (ATP).  In the sand example, the action is passive in that the sand isn't exerting energy; gravity is pulling the sand.  

Additionally, passive transport (not requiring energy) is usually used before active for two simple reasons:

-why use energy when you don't have to?

-when there is enough ATP, typically too much ADP

Answer 3

Active trqnsport is a biological process that involves the movement of mineral ions(in plants} and glucose and amino acids (in humans)from areas of low concentration to areas of  higher concetration by cellular energy.The liquid carrier  trasporting the subtsance must obey the countinuity liquid flow equation  p₁A₁v_{1 =}  p₂A₂v₂ where p, A, an v are denity, area ,and velocity repectfully.Hence for a liquid of the same density, then a flow from a larger area to a smaller area will lead to an increase in velocity and vice versa otherwise. Also more absorption of substances takes place at a larger surface than at a smaller surace. Hence liquid flows more rapidly at a smaller surface with a correponding smaller absorption rate of substances than at a larger surface   

 

 

 

 

 

   

Answer 4

Another simple way to visualize this concept is by thinking about how you would clean up a water spill when using a towel: if you placed the towel on the spill without folding it, the surface area presented to the mess would be smaller than if you fold the towel. The folded towel (as we all know from experience) will absorb the mess more effectively.

The important idea when considering rate of transport in relation to surface area, is that with increased surface area, more transporters can embedded in the membrane, in the same space, than a membrane without infolding.

Answer 5

Increasing the surface area also increases the volume, thus increasing the rate of transportation. Consider a relevant medical example: the alveoli in our lungs expand as we breath in so that gas exchange can occur. This example is meant to serve as an analogy and not as a true example where increasing volume increases active transport (because the gas exchange of carbon dioxide and oxygen is driven by diffusion across the capillaries and alveoli). Another example is seen with plants--active transport is an important process in these creatures. The uptake of mineral ions through the soil requires active transport because the ions are found in very dilute solutions, whereas the solution inside the plant cells is a lot stronger. This means the ions have to be taken in against the gradient (from dilute to concentrated), THUS resulting in active transport. The larger the root system, the more active transport that takes place = the more roots, the more surface area, the more active transport, and thus the more water absorption. 

Answer 6

The larger the surface area, the faster the rate of active transport.

Think of it like having two very populated highway entrance ramps. One ramp only has two lanes and is rather short, while the other is four lanes and longer. The wider the lane, the more cars can get through at one time. The longer the lane, the more momentum can be built up on the ramp.