Single-celled organisms have a large surface area-to-volume ratio. This means enough molecules can be transported across their cell membranes to meet their needs
Multicellular organisms have a small surface area-to-volume ratio. This means they need specialised organ systems and cells to allow enough molecules to be transported into and out of their cells
Exchange surfaces work most efficiently when they have a large surface area, a thin membrane, and a good blood supply
Villi in the small intestine for absorbing nutrients
Large surface area due to folding
Thin wall (only one cell thick)
Good blood supply
Network of capillaries
Alveoli in the lungs for gas exchange
Large surface area
Membrane is moist
Membrane is only one cell thick
Short diffusion pathway
Good blood supply from network of capillaries
fish gills for gas exchange - gills are made up of stacks of thin filaments with:
a largesurface area to increase diffusion
a network of capillaries (good blood supply)
root hair cells - for uptake of water and minerals:
lots of mitochondria- to take in mineral ions by active transport
large surface area helps efficient absorption of water and mineral ions
