Transport in Plants Flashcards
Osmosis
net movement of water from an area of high water potential to an area of low water potential through a partially permeable membrane
partially permeable membrane in cells
cell membrane in animal and plant cells. membrane around vacuole in plants
Turgid
when the plant cell has enough water to exert pressure on the cell wall and push on other cells.
plasmolysed plant cells
cause the plant to wilt as no pressure on cell walls to keep shape
microscope practical
place a drop of water on one microscope slide and a drop of sucrose solution on the other
peel two small layers of inner epidermis onion skin off of an onion and put one on each slide
put another drop of liquid on the onion skins and place a cover slip on top
observe as the onion cells in sucrose solution become plasmolysed
chips practical
cut three strips of potato of roughly same size
weigh potato strips
place each in boiling tubes one in air one in water one in sucrose solution
wait 30 minutes
weigh after and calculate mass change
process of uptake of water through roots and transport to the leaves
root hair cells increase surface area and take in water and some minerals from soil through osmosis
travels through root cortex to xylem in middle of root
xylem passes water through the stem and leaves
Transpiration
the loss of water from leaves
transpiration stream
water is taken up by roots transported through xylem and let out through the stomata in leaves in a continuous process.
supplies water to leaf to carry out photosynthesis
carries mineral ions dissolved in water
keeps plant cells turgid
cools leaf through evaporation
xylem structure
contains dead cells end to end forming vessels mature vessels have no cytoplasm and have a hollow space(lumen) that water passes through. walls of xylem contain lignin a woody material.
carries water and minerals
phloem structure
also formed by cells end to end but there are living cells instead of dead ones.
cell walls of cellulose
end of each cell formed by a cross wall of cellulose with holes called sieve plate linking one cell to the next
phloem carries products of photosynthesis and some amino acids away from leaves travelling to points of growth in plant the flow is controlled by companion cells that lie alongside the sieve tubes
draw phloem 6marks
sieve plate
companion cell
nucleus
sieve tube
cell wall
cell pores
stomata placement
on the bottom of leaves so that water isn’t lost so easily
factors affecting rate of transpiration
light intensity
temperature
humidity
wind speed
light intensity on rate of transpiration
increases in presence of light so leaf can photosynthesise
temperature on rate of transpiration
high temp = faster rate of evaporation
humidity on rate of transpiration
high humidity lowers diffusion gradient between plant and outside air slowing rate of transpiration
low humidity increases diffusion gradient increasing rate of transpiration
wind speed
increases as moving air removes water vapour near stomata increasing diffusion gradient
potometer
measures the rate of transpiration or rate of uptake of water by a plant. two versions weight and volume
weight potometer
measures loss of mass over an extended period of time multiple hours. plastic bag placed over pot so moisture does not escape through soil water will have been evaporated through the leaves and only the leaves
volume potometer
capillary tube and attached rubber tubing placed in sink of water and air is removed by squeezing the tubing. plant shoot taken and end of shoot is cut at an angle. clamp vertically. water moves up capillary tube and can the rate can be recorded by seeing how long it take to move up a set distance. repeat with a fan to investigate effect of wind speed or put under bright light to measure effect of light intensity
