The Need For Gas Exchange Surfaces Flashcards
Why don’t single celled organisms need specialised gas exchange or transport system
Because diffusion is enough to supply their needs
Why does gas exchange work in small organisms
The diffusion distances from the outside to the intermost areas are very small
their sa:vol is large - a big surface area over which substances can diffuse in or out of the orgnaism
Why is the metabolic rate higher in larger mammals
They control the thier own body temp
They are very active and have
very high metabolic rates
Why do organisms need specialised gas exchange surfaces as they increase in size
the bigger the organism gets the smaller the sa:vol ratio
the distance from the outside of the organism to the inside gets longer and there is less surface for substances to enter through
it takes longer for substances to diffuse in
it may not reach the individuals cell quickly enough to supply all their needs
How does surface area affect the rate of diffusion
the bigger the SA the more particles can be exchanged at the same time
How does the concentration gradient pf the particles diffusing affect the rate of diffusion
The more particles there are on one side of the membrane compared with the other the faster they move across
How does the distance over which diffusion is taking place affect the rate of diffusion
the shorter the diffusion distance the faster diffusion can take place
Explain how SA:VOL ratio effects transport of molecules in living organisms
The larger the SA the more particles can be exchanged at the same time
What are the factors affecting ROD?
- The Surface area
- Concentration graident
- The distance over which diffusion is taking place
Why doesnt single celled organisms and small multicellular organism do not need specialised gas exchange system?
- Diffusion is enough
- The distance from the outside to the inside areas are very small
- Metabolic demands are low
Explain why organisms need specialised gas exchange surfaces as they increase in size
Substances need to travel long distances from the outside to reach the cytoplasm of all the cells
The metabloci rates of larger organsims tend to be higher than that in smaller animals
the demands of both individual cells for oxygen and food and the amount of c02 and waste products is much higher in a mammal
