Surface Area to Volume Ratio Flashcards
Where does exchange of substances occur in multicellular organisms?
Exchange surfaces
What are the cells of multicellular organisms surrounded by?
Tissue fluid
Explain why tissue fluid is important
most cells are too far from exchange surfaces for substances to arrive or be removed by diffusion. Substances move through the tissue fluid
What is the purpose of a mass transport system?
to move substance to and fromcell surface membranes and to maintain diffusion gradients
What factors affect the amount of materials exchanged in an organism?
size and metabolic rate
Comment on the SA:volume of an organism with a high metabolic rate
it has a large SA:volume
Name the respiratory gases that need to be exchanged between an organism and its environment
carbon dioxide and oxygen
Name the nutrients that need to be exchanged between an organism and its environment
glucose, fatty acids, amino aciuds, vitamins, minerals
Name the excretory products that need to be exchanged between an organism and its environment
urea and carbon dioxide
State two types of passive transport
osmosis and diffusion
What is required for acive transport?
energy
What size organism have a large surface area to volume ratio?
small ones
Why do larger organisms require specialised exchange surfaces?
their SA:volume ratio is not sufficient to proveide substances by diffusion across their surface
Why do some organisms have a flattened shape?
So all cells are near to the surface for exchange of substances
What happens to SA:volume ratio as an organism becomes larger?
it gets smaller
