specialised exchange surfaces Flashcards
how is surface area to volume ratio calculated?
surface area / volume
what is a concentration gradient
difference between concentrations of a substance in two different areas
why is a large concentration gradient better?
the substance will diffuse faster towards the lower concentration
what happens to SA:V ratio as organisms get larger?
larger organisms = smaller SA:V ratio
describe how an organisms size affects metabolic rate
smaller organism = faster metabolic rate
describe gas exchange in single cell organisms
gases diffuse directly through cell surface membrane
why do multicellular organisms need gas exchange systems?
large SA:V ratio - the distance between cells deep in the body and outer environment is larger
what are 3 features of an efficient gas exchange system
- increased surface area
- thin membranes (for short diffusion pathway)
- steep concentration gradient (due to good blood supply and ventilation)
what is the concentration of oxygen present in the air?
21%
what are the adaptations of root hair cells that enable it to maximise water absorption?
root hair protrusions greatly increase surface area
what is an example of a structure that has an increased surface area
- root hair cells in plants
- villi in small intestine
what is an example of a structure that has thin layers
alveoli in the lungs
what is an example of a structure that has a good blood supply
- alveoli of the lungs
- gills of fish
- villi of small intestine
what is an example of a structure that has good ventilation to maintain concentration gradient
- alveoli of lungs
- fish gills
