exchange surfaces Flashcards
what are the factors that affect the need for a transport system?
surface area to volume ratio
metabolic rate
size
how can size of organisms affect rate of diffusion
small organisms : cytoplasm very close to environment in which where they live –> simple diffusion is enough
large organisms : have several layer of cells, diffusion pathway is too long –> diffusion too slow to enable a sufficient supply to the innermost cells
how does the surface area to volume of organisms ratio affect the need for a exchange system
small organisms : have small surface area but also small volume, SA is relatively large compared to volume , large surface area to volume ratio –> surface area is large enough to supply all their cells with sufficient oxygen
large organisms : have large volume but small surface area, small surface area to volume ratio –> distance needed to reach the centre of the organism is longer
how does the metabolic rate affect the need for a transport system
larger organisms : have higher metabolic rate, demands efficient transport of waste out of cells and reactants into cell –> require adaptations to increase the efficiency of exchange across their surface
Cells of an active organism need good supplies of nutrients and oxygen to supply the energy for movement –> need to keep themselves warm
how is the rate of diffusion affected
surface area
concentration gradient
length of diffusion pathway
how does large organisms adapt to increase efficiency of transport across their surfaces to maximise diffusion
surface area - projections on root hair cells
concentration gradient - ventilation, good blood supply and countercurrent flow mechanism
length of diffusion pathway - alveoli walls, one cell thick
