GAS EXCHANGE I
, The rate of gas exchange depends on the organism’s surface area that is in contact with
the surroundings
The bigger the organism = the smaller their surface area : volume ratio
As organisms become bigger it becomes more difficult to exchange materials
with their surroundings
Larger organisms need 3 features to survive :
1) Multicellular - their bodies are composed of many small cells, rather than one big cell
2) Mass Transport System - uses energy to pump nutrient solutions quickly around large
bodies. Mass transport systems include blood systems of animals and vascular systems
of plants
3) Specialised Exchange System- (with a large surface area) e.g) lungs, gills, intestines,
roots and leaves
Fick’s Law : Rate of diffusion a surface area x concentration difference
thickness of exchange surface
In order to support a fast rate of diffusion, exchange surfaces must have :
- large surface area
- small distance bet ween source and destination
- mechanism to maintain high concentration gradient
, The rate of gas exchange depends on the organism’s surface area that is in contact with
the surroundings
The bigger the organism = the smaller their surface area : volume ratio
As organisms become bigger it becomes more difficult to exchange materials
with their surroundings
Larger organisms need 3 features to survive :
1) Multicellular - their bodies are composed of many small cells, rather than one big cell
2) Mass Transport System - uses energy to pump nutrient solutions quickly around large
bodies. Mass transport systems include blood systems of animals and vascular systems
of plants
3) Specialised Exchange System- (with a large surface area) e.g) lungs, gills, intestines,
roots and leaves
Fick’s Law : Rate of diffusion a surface area x concentration difference
thickness of exchange surface
In order to support a fast rate of diffusion, exchange surfaces must have :
- large surface area
- small distance bet ween source and destination
- mechanism to maintain high concentration gradient
