View
219
Download
0
Category
Preview:
Citation preview
IT’S A IT’S A GREEN WORLDGREEN WORLD
WATER, WATER WATER, WATER
EVERYWHEREEVERYWHERE
StarterStarter
Raise your hand when you can smell Raise your hand when you can smell the perfume…………………the perfume…………………
Why is perfume put on Why is perfume put on the warm places of the warm places of the body such as the the body such as the neck and wrists? neck and wrists?
Water, water Water, water everywhereeverywhereLearning objectivesLearning objectives Describe osmosisDescribe osmosis
Describe the effects of Describe the effects of the uptake and loss of the uptake and loss of water on plant and water on plant and animal cells.animal cells.
Explain the key terms: Explain the key terms: flaccid, plasmolysed, flaccid, plasmolysed, turgid, crenation and turgid, crenation and lysislysis
Success criteriaSuccess criteria Know the definition of Know the definition of
osmosisosmosis
Be able to understand Be able to understand and describe the effects and describe the effects of different of different concentrations of sugar concentrations of sugar solutions on plant cells solutions on plant cells
Be able to understand Be able to understand and therefore use the and therefore use the key terms correctly key terms correctly
Recap of diffusion
Diffusion and concentrationWhy can the student smell the sock from a distance?
The sock can be smelt because sweat and other molecules are moving away from it and spreading out in the air. This is called diffusion.
Where is the smell strongest?
The smell is strongest at the sock. The smell becomes weaker further away from the sock.
Changing concentrations
The rate of diffusion depends on several factors, such as the distance the particles have to travel and the difference in concentration.
Molecules diffuse until they are evenly spaced apart and equilibrium is reached.
During diffusion molecules move from an area of high concentration to an area of low concentration. They are said to move down a concentration gradient.
Diffusion is a passive process which means that no energy is needed.
highconcentration
lowconcentration
What is osmosis?
water
glucose
partially-permeablemembrane
(visking tubing)
Osmosis is the diffusion of water molecules from a low concentration solution to high concentration solution, across a partially-permeable membrane.
A partially-permeable membrane has holes in it that permit water molecules through but are too small to allow larger molecules through. Osmosis can be demonstrated using visking tubing filled with a solution and placed in a beaker of pure water.
Osmosis demoOsmosis demo
BeforeBefore After After
Dilute vs. concentrated
Concentrated solutions have a low concentration of water molecules.
Dilute solutions have a high concentration of water molecules.
During osmosis, water molecules diffuse from pure water or dilute solution to more concentrated solutions.
pure water dilute solutionconcentrated
solution
Support in plant cellsSupport in plant cellsWater can move in and out of a plant cell Water can move in and out of a plant cell
through itsthrough its Cell wall - permeableCell wall - permeable Cell membrane – partially permeableCell membrane – partially permeable
The presence of water in a plant cell gives The presence of water in a plant cell gives itit
Shape Shape Support Support
The cell wall also provides supportThe cell wall also provides support
Support in plant cellsSupport in plant cells
What happens when water uptake What happens when water uptake and water loss are not balanced a and water loss are not balanced a plant?plant?
The plant will wilt.The plant will wilt.
Osmosis and cellsPlant and animal cells are surrounded by a partially-permeable plasma membrane. This allows water and other small molecules to diffuse across.
plant cellred blood cell
cell wall
Plant cells additionally have a strong cell wall surrounding the membrane which offers support and protection.
plasmamembrane
HD onlyHD only - More on osmosis - More on osmosisWhen a potato chip is in salt water the When a potato chip is in salt water the
chips become flaccid (soft and floppy). chips become flaccid (soft and floppy).
WHY?WHY?
There is a higher concentration of water There is a higher concentration of water molecules inside the potato cells than molecules inside the potato cells than outside. Water leaves the cells by outside. Water leaves the cells by osmosis and the cells become osmosis and the cells become plasmolysed.plasmolysed.
Osmosis and plant cells
Osmosis and animal cellsAnimal cells do not have a cell wall. This means they respond differently to plant cells to the gain and loss of water.
In concentrated solutions, water loss causes the cells to shrink. When this happens to red blood cells, it is called crenation.
In dilute solutions, osmosis can cause animals cells, such as red blood cells, to swell up and burst. This is called lysis.
Osmosis and animal cells
Osmosis in onion cellsOsmosis in onion cells
Follow instructions on w/s B4b5 – Follow instructions on w/s B4b5 – osmosis in onion cellsosmosis in onion cells
OsmosisOsmosisWeak solution Concentrated solution
crenated
NormalTurgid
Normal
Plasmolysed
Lysed
Plenary - Predicting Plenary - Predicting osmosisosmosis
Water, water Water, water everywhereeverywhereLearning objectivesLearning objectives Describe osmosisDescribe osmosis
Describe the effects of Describe the effects of the uptake and loss of the uptake and loss of water on plant and water on plant and animal cells.animal cells.
Explain the key terms: Explain the key terms: flaccid, plasmolysed, flaccid, plasmolysed, turgid, crenation and turgid, crenation and lysislysis
Success criteriaSuccess criteria Know the definition of Know the definition of
osmosisosmosis
Be able to understand Be able to understand and describe the effects and describe the effects of different of different concentrations of sugar concentrations of sugar solutions on plant cells solutions on plant cells
Be able to understand Be able to understand and therefore use the and therefore use the key terms correctly key terms correctly
Recommended