Osmosis And Plant Transport Flashcards
(48 cards)
Osmosis
Diffusion of water molecules from a dilute solution to a more concentrated solution through a selectively permeable membrane
Osmosis in plants -Turgid
When water enters a plant cell, the vacuole increases in size, pushing the cell membrane against the cell wall. The force of the membrane pushing against the cell wall increases the presssure making it firm or-turgid. This pressure prevents too much water entering thus stops it from bursting.
Why a cell wants to be turgid
🌲Prevents too much water from entering and stop cell from bursting.
🌲Gives plant cell support and in non woody plants this is essential in keeping the plant upright
Flaccid
When plants do not receive enough water, they cannot remain turgid and wilting occurs.
What happens if a cell is placed in a more concentrated solution than that of the cell contents
🌹If a plant cell is placed in a more concentrated solution than that of the cell the water molecules will move out of the cell.
🥀As a result the cytoplasm and vacuole will shrink. 🥀Since water provides support in plant cells as water moves out of the cells the plant will appear wilted.
🥀Eventually so much water will move out of that the cell membrane pull away from cell wall.
🥀Now described as being plasmolysed.
Osmosis in animal cells
Water moves into the cell, cell increases in volume, stretching cell membrane. If this continues, the cell membrane will eventually split and burst -cell lysis.
Why does the red pigment in the rhubarb move out of the cell
Pigment molecules are too big to fit through selectively permeable cell membrane
Temperate affect rate of transpiration
☀️ use a heater to change/vary it
☀️effect on result of photometer experiment. Higher temp -> more water loss.
☀️more evaporation
What do you find in space between cell wall and cell membrane
Sugar solution
Rate of transpiration formula
Change in mass / org mass x100
Independent, dependent, controlled variables
Change, measure, keep same
Explain results from osmosis by measuring change in mass of plant tissue in solutions of diff conc
At 0% and 5% sucrose the weight increased. There was a higher conc of water outside the cell, more water randomly moved in by osmosis causing weight to increase. At 10% 15% and 20% sucrose the weight decreased. The high conc water now inside cell, water moved out by osmosis causing cells weight to decrease
Explain results for osmosis using a visking tubing
Weight increased by 3g. Higher conc water is outside the vt. this diffuses into the vt and sucrose is to big to get out so weight increases. More water will randomly move out than in, sucrose to big and can’t leave. Water moved in by osmosis.
Transpiration
Evaporation from mesophyll cells followed by diffusion through airspaces and stomata
Uses of Water in plants
Transport
Minerals and sugar are transported through the plant, dissolved in water
Uses of Water in plants
Support
Water will be used to make cells Turgid and prevent leaves from wilting
Uses of Water in plant
P/s
6CO2 + 6H20 -> C6H12O6 + 6O2
Uses of Water in plants
Transpiration
Water evaporates out from leaf cells and diffuses out the stomata pore cresting a continuous flow of water through the Xylem vessels from root to leaf.
What is the function syringe/reservoir?
Reset bubble back to start so experiment can be repeated
What is the problem if the bubbles moves away from the shoot?
Not air tight, air is entering
What can happen to the water
P/s, support/ make cells turgid, transpiration
Factors affecting transpiration
Wind
🌪 fan
🌪increases wind -> faster uptake water
🌪wind blows water vapour away from leaf maintaining diffusion gradient
Factors affecting transpiration
Humidity
💧plastic bag over plant
💧increased humidity -> less water loss
💧decreases diffusion gradient high - high
Factors affecting transpiration
SA of leaves
☘️remove leaves
🍀decreased SA -> less water loss
🍀less leaves, less stomata for diffusion of water
