Exchange Surfaces
- Created by: Klmcgonigle
- Created on: 31-01-18 16:17
View mindmap
- Exchange Surfaces
- Living cells need oxygen and nutrients to survive, and removal of waste to avoid toxicity
- Features of a good exchange surface
- Large surface area
- provides more space for molecules to move through = increased rate of diffusion
- E.G root hair cells
- Thin layer
- E.G alveoli
- Reduces the diffusion distance to increase the rate of diffusion
- (barrier must be permeable)
- Good blood supply/ventilation
- Maintains steep concentration gradient so rate of diffusion is high
- E.G gills
- Large surface area
- Factors that affect the need for an exchange system
- Size
- Small organisms (amoeba): cytoplasm close to external environment - diffusion is sufficient
- Large organisms: several layers of cells - longer diffusion pathway, so diffusion is too slow to be sufficient
- SA:V ratio
- Small organisms: large SA:V ratio - area is large enough to supply all cells with sufficient O2
- Large organisms: small SA:V ratio - area not large enough to supply all cells
- Level of activity
- Larger organisms (mammals, warm blooded) need more energy for their more active metabolism, and therefore more O2
- Size
- the need for specialised exchange surfaces To include surface area to volume ratio (SA:V), metabolic activity, single-celled and multicellular organisms. (b) the features of an efficient exchange surface To include, • increased surface area – root hair cells • thin layer – alveoli • good blood supply/ventilation to maintain gradient – gills/alveolus
Comments
No comments have yet been made