diffusion definition
a net movement of particles from an area of high to low concentration
diffusion factots
different concentrations
temperature
surface area
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diffusion definition
a net movement of particles from an area of high to low concentration
diffusion factots
different concentrations
temperature
surface area
small intestine role
most absorption of digested food molecules into the bloodstream occurs across the wall of the small intestine
small intestine adaptations
highly folded SA, lined with specialised epithelial cells, increasing SA
one layer of epithelial cells covers the surface of each villus, decreasing diffusion distance
each villus has a good blood supply, maintaing a concentration gradient
lungs role
gas exchange between air in the alveoli and the blood, to supply cells with oxygen for aerobic respiration and to remove carbon dioxide
lungs adaptations
millions of alveoli, which collectively provide a huge surface area, increasing SA
the wall if each alveolus is one cell thick with a moist lining and excellent blood supply, maintain a concentration gradient
gills role
gas exchange between water flowing through the gills and the blood, to supply cells with oxygen for aerobic respiration and to remove the waste product co2
gills adaptations
made from lots of smaller plates called filaments, which themselves are covered in projections called lamellae, increasing SA
dense capillary network ensures a good supply flows in the opposite direction to water passing through gills, maintaining a concentration gradient
roots role
to absorb water and mineral ions from the soil and anchor the plant
roots adaptations
network is highly branched, increasing SA
the surface of roots are covered in root hair cells which have a specialised structure with root hair projections, increasing SA
leaves role
contain most of a plants photosynthetic plants
leaves adaptions
stomata are tiny openings that predominantly cover the lower side of the leaf allowing air to circulate inside the leaf, decreasing diffusion distance
osmosis definition
the net movement of water molecules from a dilute to concentrated solution through a partially permeable membrane
dilute
a solution with a high concentration of water
concentrated
a solution with a low concentration of water
osmosis RP aim
to investigate the range of concentrations of salt or sugar solutions on the mass of plant tissue
osmosis RP method
prepare samples of potatoes and place in different concentrations of sugar solutions
make measurements of mass and length of samples before and after soaking them in solutions
calculate the percentage change in mass
plot and draw graphs
osmosis RP variables
independent: concentration of sugar solution
dependent: mass and length of potato before and after
control: temperature, time
active transport definition
the movement of substances across a cell membrane from an area of low to high concentration