3.3.1 Surface area to volume ratio (Unit 3 Exchange) Flashcards
The name given to the environment surrounding a cell
tissue fluid
Single celled organisms can match their metabolic demands by
simple diffusion
Exchange of materials in living organisms occurs at ..
exchange surfaces e.g. lungs, intestine
How much material that needs to be exchanged in an organism depends on
its size and its metabolic rate
Substances a cell exchanges with its environment include
oxygen, carbon dioxide, nutrients (glucose)
Exchange of materials in living organisms takes place via (4 types of transport)..
simple diffusion
facilitated diffusion
osmosis
active transport
As an organism gets larger what happens to its surface area to volume ratio?
its gets smaller - less efficient exchange.
Special exchange surfaces therefore required i.e. lungs
How do larger organisms cope with their increasing size?
They have specialised exchange surfaces - which have large surface area:volume ratio!
OR
they are flat and thin therefore no cell is too far away from the surface
What is ficks law?
diffusion rate is directly proportional to surface area x difference in concentration divided by length of the diffusion pahway
How are specialised exchange surfaces adapted?
- Large surface area to volume ratio
- Thin - short diffusion pathway
- Selectively permeable
- Extensive blood supply to maintain concentration gradient
single celled organisms SA: volume ratio is described as
large surface area to volume ratio
single celled organisms obtain their nutrients via..
simple diffusion
Why are insects usually small
their tracheal system relies on diffusion, for this to be efficient the diffusion path needs to be short and this is only achieved if the insects are small
Maths Skills:
If a cube had a side length of 1cm, what would it’s SA be?
6 cm2
Maths Skills:
If a cube had a side length of 1cm, what would it’s volume be?
1 cm3
