Exchange Between Organism and Their Environment (General Features of Ex.…
Exchange Between Organism and Their Environment
All animals must:
Maintain a supply of materials needed for res. and growth
Gases, Nutrients AA, glycerol, products of digestion
Remove waste products of metabolism
Net movement of molec. from area of HIGH conc. to an area of LOW conc.
Need for an Exchange Surface
Small or. diff. across their body surface is sufficient:
SA relatively large
Body/cell surface acts as exchange surface
Large (multicellular) active org. can't rely on body surface
SA:V is insufficient for ex.
Diff. path. too long
Effect of Inc. of Size on Ex. Surface
As size inc. SA inc. more compared to vol.
Metabolic rate of org. inc. disproportionally. T/f demands 4 nutrients + waste removal inc.
T/f org. need:
Adaptions in size + shape of body
Specialisd Ex. surf. to meet demands
Efficient transport system to deliver materials to and from Ex. surf.
General Features of Ex. Surf.
provided by body surf. of small org. / by folding ex. surf.
To allow materials to pass
Short diff. path. inc. rate
O2, CO2 + nutrients Diff. in solution
Mechanism to maintain diff. grad.
Transp. sys., ventilation mechanism / creation of currents across surf.