Osmosis and Plant Transport
Mind map covering whole chapter on Osmosis and Plant Transport. CCEA revised Unit 2 chapter 8.
- Created by: Abigail
- Created on: 13-06-13 14:51
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- Osmosis and Plant Transport
- Definitions
- Selectively permeable: Allows some substances to pass through but prevents the movement of others
- Diffusion: the random movement of a substance from where it is in high concentration to where the concentration is lower
- Osmosis: A special type of diffusion involving the movement of water molecules through a selectively permeable membrane
- Osmosis
- Water moves from the weaker (more dilute solution to the stronger (more concentrated solution through a selectively permeable membrane
- In osmosis water molecules move but other larger molecules such as sugar cannot move through the selectively permeable membrane
- A concentration gradient exists across a selectively permeable membrane
- Concentration gradient: difference in concentrations on either side
- Osmosis in plant cells
- When water moves into the plant cell, the vacuole increases in size, pushing the cell membrane against the cell wall
- Cell wall stretches slightly-cell becomes turgid
- Cell wall prevents too much water from entering the cell and causing it to burst
- When plants do not receive enough water they cannot remain turgid and wilting occurs - they become flaccid
- If a cell loses to much water plasmolysis occurs. So much water leaves the cell that the cell contents shrivel, pulling the cell membrane away from the cell wall
- Osmosis in animal cells
- Animal cells do not have a cell wall so water entering and leaving the cell cannot be controlled
- If too much water enters the cell through osmosis, it fills with so much water that it bursts
- If the cell is in e.g a strong sugar solution, so much water will leave the cell that it shrivels up- crenation
- Transpiration
- Transpiration is the loss of water by evaporatio
- The evaporation of water takes place mainly in plant leaves from the spongy mesophyll cells, through the air spaces and out of the stomata
- Main functions of water in the plant
- transpiration
- photosynthesis
- transport
- support
- measuring water uptake using potometer
- average rate of movement=distance moved by bubble/time taken
- Environmental Factors affecting transpiration
- temperature
- wind speed
- humidity
- light
- Definitions
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