Gas Exchange Flashcards
What increases the rate of diffusion on gas exchange surfaces
Large surface area
Thin
Steep concentration gradient
Gas exchange in single celled organisms
They absorb and release gasses by diffusion through their cell membranes
Large surface area and thin surface so oxygen can take part in biochemical reactions as soon as it diffuses into the cell so there’s no need for specialised gas exchange system
Why do fish have to have special adaptations to get enough oxygen
And what do they have
Theres a lower concentration of oxygen in water than in air
In the exchange surface there is gills
Structure of gills
Each full has lots of thin plates called gill filaments which give a large surface area
Gill filaments have lots of lamallae which increase the surface area
Lamallee have lots of bloody capillaries and a thing surface layer of cells to speed up diffusion
The counter current system
Where the blood flows through lamallae in one direction and water flows over in the opposite direction
Counter current system means the water with high oxygen concentrations flow next to the blood with low concentration of oxygen
This means a steep concentration gradient in maintained between the water and blood so as much oxygen can diffuse through as possible
Gas exchange in dicotyledonous plants structure
Have mesophyll cells which have large surface area
Gases move in and out through stomata
The stomata can open to allow exchange in gases and close if plant is losing too much water
Guard cells control the opening and closing
Gas exchange in insects process
Air filled pipes called tracheae
Air moves into tracheae through pores called spiracles
Tracheae branch off into tracheoles which are thin
Carbon dioxide from the cell moves down its own concentration gradient towards the spirit as to be released
Xerophyte plants adaptations to control water loss
Sunken stomata to trap water vapour reducing concentration gradient of water between leaf and air reducing water evaporation
Layer of hairs on epidermis trap water vapour
Circles leaves protect plant from wind
Reduced number of stomata so fewer places for water to escape
Thick waxy cuticle which are waterproof to reduce evaporation
