6.1 Exchange between organisms and their environment

Question	Answer
what is Tissue Fluid ?	the environment around the cells of multi cellular organisms
what effects amount of each substance that is exchanged ?	Size Metabolic Rate
what happens when an organism has a High Metabolic Rate	~ exchange More materials ~ Need Large SA:V ration -> reflected in type of Exchange surface and Transport system ( to meet requirements )
what Substances need to be Interchanged between organism and environment	~ Respiratory gases (O2, CO2) ~ Nutrients (Glucose, fatty acids, vitamins) ~ Excretory products (Urea & CO2) ~ heat
Surface Area : Volume	exchange surface must be large compared to Volume -> to allow sufficient exchange
what features must organisms develop ?	1. Flattened shape -> no cell is Never Far from surface -> e.g flatworm , eaf 2. Specialised exchange surface -> Large area, to increase SA:V ratio -> e.g lungs in mammals, gills in fish
how are Specialised exchange Surfaces by diffusion/ active Transport Adapted ? 1	~ Large SA:V ratio -> increases Rate of Exchange ~ Very thin, diffusion pathway short -> materials cross surface rapidly ~ Selectively Permeable, selected stuff to cross
how are Specialised exchange Surfaces by diffusion/ active Transport Adapted ? 2	~ Movement of external environmental medium e.g air flow -> maintain Diffusion gradient ~ a Transport system, to ensure Movement of Internal enviroment -> e.g blood flow to maintain diffusion gradient
Diffusion equation?	Image: Boardworks+As+Biology+Transport+Across+Membranes (image/jpeg)

Resource summary

	Created by Sea Chel Pie almost 6 years ago