WJEC biology gas exchange
- Created by: rachel
- Created on: 08-05-13 12:47
View mindmap
- Gaseous exchange
- Fish
- surface = gills
- many folds providing large S.A. and specialised
- 2 main groups
- cartilaginous fish- skeleton is cartilage
- Blood and sea water parallel flow (in gill capillaries) = inefficient
- Bony fish- bone skeleton
- Gills covered by flap (operculum)
- counter current flow - blood in gill capillaries flow in opposite direction to water
- increases efficiency- D gradient maintained through out
- cartilaginous fish- skeleton is cartilage
- surface = gills
- mammals (humans)
- plants
- insects
- other examples
- respiratory surfaces- evolved diffusion in and out of cells take place rapidly and efficiently
- large S.A:Vol
- thin- diffusion pathway short
- permeable
- increase size
- unicellular organisms *Diffusion over whole body surface *Large SA:Vol *Thin and moist membrane *short D paths
- multicellular evolved special gaseous exchange mechanisms with surfaces generally located inside organism. Ventilation needed- moving air over surface
- Fish
Comments
No comments have yet been made