Exchange and Transport in Protozoa :: Biology

Exchange and Transport in ProtozoaThe exchange of gases between the environment and cells occurs via the puzzle out of diffusion. Diffusion depends on The amount of surface expanse available for diffusion. The bigger the surface area the great the rate of diffusion. The concentration gradient. An organism which respires very speedily will have a much lower concentration of oxygen in the cells and a higher than normal concentration of Carbon Dioxide. So the greater the concentration gradient across the respiratory surface the quicker the rate of diffusion. The thickness or length of the diffusion path. The greater the thickness of the path the unhurried the rate of diffusion because the gases will have to travel a larger distance. So the respiratory surface must be as thin as possible.The relation of the three points above can be summed up by Ficks LawHowever, the amount of gas which an organism needs to exchange isgreatly proportional to its people, nevertheless, the amo unt ofgaseous exchange which takes place is proportional to the surface areaover which the exchange happens.For single celled/unicellular organisms the surface area to volumeratio is large, however, for larger organisms the surface area tovolume ratio decreases. The larger the object gets the morecomplicated it gets.The smaller the object the larger thesurface area to volume ratio. This is where single celled organismhave an advantage. Organisms like Amoeba can exchange gases withenvironment quickly and easily. However exchange surfaces need toattain authoritative properties to maximise gaseous exchange. They are Need to have a good blood supply- high concentration gradient Moist- Dissolve gases Large Surface surface area Thin walls PermeableAs single celled organisms are small so they do not have to havespecialised systems like much larger organisms like mammals. Singlecelled organisms like amoeba do not have to have transport systems orspecialised systems because they are so sma ll so IMAGEsubstances donot have to travel far to get to their desired destination.The contractile vacuole in this amoeba is used for water regulation.