3.3.1 Surface area to volume ratio Flashcards
Where does most gas exchange occur?
At the cell membranes
What is surface area?
The total area of the part of a cell which are in direct contact with the environment
What is cell volume?
A measure of the size of the contents of the cell
What does SA:V determine?
The rate of exchange
How do you calculate SA:V ratio?
Surface area/Volume
As cells grow, what happens to surface area : volume ratio?
It will decrease
What effect does large SA:V ratio have on rate of exchange?
The larger the ratio, the faster the rate of diffusion
Which object has a bigger SA:V ratio? An apple or a car?
An apple
Why can unicellular organisms rely on diffusion?
- High SA:V ratio
- Small diffusion pathway
- Small demand for substances
Why can’t large organisms rely on simple diffusion?
- Low SA:V ratio
- Long diffusion pathway
- High demand for substances
What adaptations do organ systems have for a high exchange rate?
Structures and cells with large surface areas, e.g. the alveoli
How can a larger surface area be achieved?
By having more folds
Why do organisms with high metabolic rates need an exchange system?
As they have a high oxygen demand
