Osmosis and Transpiration Flashcards
What is Diffusion
Diffusion is the random movement of substances (gasses or liquid) from a high concentration until they are evenly spread
What is Osmosis
Osmosis is the movement (diffusion) of water from a dilute solution to a more concentrated solution through a selectively permeable membrane.
How does osmosis move the water
Higher concentration of water to a lower concentration of water
What happens when water moves into a plant cell by osmosis?
Water moves in so that the cytoplasm (and vacuole) increases in volume. The cell membrane is pushed up against cell wall. Pressure inside cell increases and cell is turgid.
What does an animal cell not have that causes cells to burst because of too much water? (cell lysis)
Cellulose Cell Wall
What is a turgid cell?
A turgid cell is a plant cell that is swollen. It has a swollen vacuole
What is Plasmolysis
Plasmolysis is whenever a plant cell has too much water leave the plant and its contents shrink.
What happens to a plasmolysis cell
The cell membrane gets pulled away from the cell wall.
Vacuole gets smaller
Why do plants use water
for photosynthesis,
for cooling
transport minerals and nutrients from the soil and into the plant
Keep cell turgid
What is the steps in the potato cylinder practical
Cut potatoes into shapes of similar length and mass
Record potato cylinder length and mass
Put potato cylinders into each solution
Wait a time period for potato cylinders to fully do osmosis
Weigh and measure potato cylinders and record change
Calculate percentage change
What is the steps in the visking tubing practical
Add 5% sucrose solution toa section of visking tubing ensuring the tubing is tied securely at each end
Dry the outside of tubing if necessary and weigh tubing and contents
Add visking tubing to beaker of water and leave for at least 1 hour
Pat dry outside of Visking tubing and reweigh
Describe and explain results obtained
Why would Visking tubing increase in mass in a beaker of water with 5% of sucrose in visking tubing
This is because sucrose solution is hypertonic to water - It is a more concentrated solution. Net movement of water molecule by osmosis from water outside to the sucrose solution inside visking tubing across partially permeable membrane
What is Transpiration
Transpiration is the evaporation of water from the spongy mesophyll cells in plant leaves through air spaces and subsequent diffusion through stomata
What is the Transpiration Stream
Transpiration stream is the continuous movement of water through plant from roots to the leaves
Describe the pathway water and minerals from the soil to the leaves in the Transpiration System
Water moves into root hair cells by osmosis
water passes from cell to cell in the root until reaches the vessels
Water is then sucked up the Xylem vessels(in stem) and moves into veins and then to leaves
Once inside mesophyll cells in the leaf the water evaporates
if there is a higher concentration of water vapour the air spaces of the leaf than there is outside the leaf then water vapour diffuses out of the leaf through stomata
What is the Bubble potometer
Bubble potometer measures water uptake in leafy shoot. As water evaporates from leaves and diffuses out through stomata in the cut shoot the shoot sucks water up through potometer. Distance an air bubble moves in a period of time e.g. 1 hour can be used to calculate rate of water uptake
What is the Weight Potometer
Take a plant and place into a conical flask containing water
Cover water with oil to prevent any evaporation from water in flask
Record the mass and leave it for 2 hours and re weigh
Any loss in mass is due to transpiration of from leaves
To calculate rate per hour divided the reading by 2
Repeat same experiments same plant in same temperature but this time mist plant to increase humidity around levels (possible to cover plant with clear plastic bag to keep humidity in)
Reweigh after 2 hours and compare results
To increase abilities repeat each of the search calculate and average
How does Windy conditions affect rate of transpiration in plants
Windy conditions increase rate of transpiration. Water molecules are blown aaway from leaf surface, so more diffuse out of the stomata
How does Humid conditions affect rate of transpiration in plants
Decrease rate of transpiration
Air contains a lot of water already
How does Warm conditions affect rate of transpiration in plants
Increase rate of transpiration
Increases evaporation in leaf
How does light conditions affect rate of transpiration in plants
Causes stomata to open thus increasing rate of transpiration
How does Leaf surface area affect rate of transpiration in plants
Larger or more leaves will have more stomata through which water can evaporate
