size and surface area
- Created by: Margaret Hobart
- Created on: 09-05-21 12:25
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- surface area to volume ratio
- relationship between surface are and volume
- smaller animals have higher SA:VOL ratio
- substance can diffuse directly into/out of the cell across the CSM
- this is fast
- substance can diffuse directly into/out of the cell across the CSM
- As the size of the organism increases, volume increases faster than surface area
- low SA:VOL ratio
- difficult to exchange enough substance to supply a big volume of animal through a relatively small outer surface
- diffusion across outer membrane is too slow
- big distance between cells and outside environment
- low SA:VOL ratio
- smaller animals have higher SA:VOL ratio
- specialised exchange surfaces
- large SA:VOL ratio
- e.g. microvilli
- thin for short diffusion distance
- Alveolar membrane
- what is exchanged
- oxygen and carbon dioxide
- glucose, amino acids and nutrients
- urea
- selectively permeable
- keeps concentrationgradient
- large SA:VOL ratio
- metabolic rate
- Smaller organisms have a higher basal metabolic rate per unit of body mass
- High metabolic rate = more materials exchanged
- relationship between surface are and volume
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