Osmosis & Plant Transport Flashcards
Concentration gradient
3 marks
Difference in concentration between;
- 2 solutions
- different cells
- or cells + a surrounding solution.
Flaccid
1 mark
Lacking turgor.
Lacking in stiffness or strength. Soft + floppy.
Humidity
2 marks
Amount of water vapour in the atmosphere measured as a percentage.
Potometer
1 mark
Device used to measure the rate of water uptake by a plant.
Selectively Permeable
1 mark
Property of a membrane that controls the movement of molecules depending on their size.
Transpiration
2 marks
Loss of water from leaves by evaporation through the stomata.
Turgid
1 mark
Having turgor; enlarged and swollen with water.
Visking tubing
2 marks
An artificial, partially-permeable membrane used in osmosis + diffusion experiments.
(Selectively/) Semi-permeable membrane
2 marks
- Allows some small substances to pass through
- Prevents larger substances.
Cell wall permeability
2 marks
Fully permeable - does not control what enters + leaves cell.
Cell membrane structure
2 marks
Rigid - provides a plant cell with support + keeps non-woody plants upright.
Osmosis in Cells depends on
1 mark
Concentration of water surrounding it.
Animal cells - osmosis
2 marks
When water moves into an animal cell - cell membrane stretches + cell gets bigger.
Example of an Animal Cell
1 mark
Red blood cell
Lysis
1 mark
Cell membrane bursts due to excess water intake.
Membrane stretches - gets bigger, then bursts due to excess water intake
(1 mark)
Lysis
Turgidity in plant cells
5 marks
Water diffusing into a plant cell = vacuole gets bigger, pushing cell membrane against the cell wall.
Force of this increases turgor pressure within cell making it firm or turgid.
When vacuole expands cell membrane is pushed against cell wall - pressure created by cell wall during osmosis in the Cells…does what?
(2 marks)
Stops too much water entering + prevents cell lysis.
If plants do not receive enough water
2 marks
Cells cannot remain turgid + plant wilts.
Cells that are not turgid
1 mark
Are flaccid.
Plasmolysis
1 mark
When too much water moves out of a plant cell + cell contents shrink - pulling the cell membrane away from the cell wall.
Cell state unlikely to survive
1 mark
Plasmolysed cell
Transpiration
4 marks
Evaporation of water from spongy mesophyll cells
- followed by diffusion of water through the air spaces + out of the stomata.
Transpiration stream
2 marks
Water in a plant that exits the leaf into the atmosphere
- providing a continuous stream of water.
Importance of transpiration stream
5 marks
Provides;
- leaves with continuous supply of water (for photosynthesis).
- plant cells with support from turgor.
- water for transpiration.
Continually transports minerals from roots, to leaves + other parts of plant.
If water availability is limited - plants…
1 mark
Will need to reduce transpiration.
How to reduce transpiration.
2 mark
Stomata close (lower side of leaf)
Effect of surface area (non-environmental factor) on transpiration.
(2 marks)
Smaller leaves will contain less stomata - causing a decrease in transpiration.
Effect of wind speed on transpiration.
3 marks
Higher wind speed - increase rate of evaporation
Causing an increase in transpiration.
Effect of temp on transpiration.
3 marks
Higher temp - will increase the rate of evaporation
Causing an increase in transpiration.
Increase rate of evaporation
1 mark
Increased rate of transpiration.
Effect of humidity on transpiration
3 marks
Higher humidity level - will reduce the rate of evaporation
causing a decrease in transpiration.
Decreased rate of evaporation
1 mark
Decreased rate of transpiration.
Effect of light intensity on transpiration.
3 marks
Darkness will cause the stomata to close - causing a decrease in transpiration.
Smaller leaves will contain less stomata causing a decrease in transpiration:
How can we change this factor Experimentally?
(1 mark)
Remove leaves.
Higher wind speed will increase the rate of evaporation causing an increase in transpiration:
How can we change this factor experimentally?
(1 mark)
Use a fan.
Higher temp will increase the rate of evaporation causing an increase in transpiration.
How can we change this factor experimentally?
(1 mark)
Use a heater.
Higher humidity level will reduce the rate of evaporation causing a decrease in transpiration:
How can we change this factor experimentally?
(2 marks)
Place a clear, plastic bag over the plant shoot.
Darkness will cause the stomata to close causing a decrease in transpiration:
How can we change this factor experimentally?
(1 mark)
Use a lamp.
If less is water being lost through transpiration.
1 mark
Plant will absorb less water at the roots.
Potometer
2 marks
Apparatus designed to measure water uptake in a leafy shoot.
2 types of potometer
2 marks
Bubble potometer + Weight potometer.
Water is transpired from ______ .
1 mark
Leaves
_____ absorbs water from the potometer.
1 mark
Shoot
What can be used to calculate the rate of water uptake?
2 marks
Distance the air bubble moves in a certain period of time
What can the movement of air bubbles (under time constraints) be used to measure?
(1 mark)
Rate of water uptake by Plant.
Potometer - the apparatus
7 marks
Set up under water - prevent entry of unwanted air bubbles.
Junction between shoot + potometer is sealed - prevent air leaks.
Apparatus reset using reservoir/syringe so water uptake in the same leafy shoot can be measured – making the investigation more reliable.
What is the junction between the shoot and potometer sealed usually sealed with?
(1 mark)
Petroleum jelly
Why is the potometer set up under water?
1 mark
Prevent entry of unwanted air bubbles.
Potometer is reset using the 1._________ or 2._______ so that water uptake in the same leafy shoot can be measured.
(2 marks)
- Reservoir
2. Syringe
Why is the junction between the shoot + potometer sealed?
1 mark
Prevent air leaks.
Examples of factors that the potometer can investigate
4 marks
Light intensity,
humidity,
temp
+ wind speed
When investigating the effect of an environmental factor what is important?
(1 mark)
All others factors are kept constant to ensure the experiment is valid.
Weight potometer - how to use:
6 marks
Apparatus + plant weighed + left for a period of time.
When reweighed the amount of water lost by the plant can be calculated.
Top pan balance that measures to 2 decimal points provides great accuracy.
What provides great accuracy when using a weight potometer?
1 mark
Top pan balance that measures to 2 decimal points.
Potometer can measure the amount of water taken up by a leafy shoot but cannot provide
(3 marks)
An accurate value for the amount of water transpired
- because some water will be used in photosynthesis + to provide turgor.
Potometer can measure
1 mark
Amount of water taken up by a leafy shoot.
