1. Osmosis & Diffusion Regulating water flow in and out of cells
in Plants and organisms living in
Fresh
And
salt water

2. Osmosis & Diffusion
Remember, Osmosis is the diffusion of water through a differentially permeable membrane.
Diffusion is a tendency of particles in a gas or liquid to become evenly distributed by moving from areas of greater concentration to areas of lesser concentration.

3. The less scientific version…
Water passes freely through membranes that surround the cells in living organisms
Particles other than water aren’t able to pass freely through these membranes. Ex. Salt is made of large Na (sodium) and Cl (chlorine) particles.
Water has a “desire” to be equally concentrated in its environment

4. Hypotonic vs Hypertonic
Water moves into the Water moves out
cell from outside of the cell

5. Osmosis Problems
Cells living in freshwater will freely allow water to enter through their cell membranes. The concentration of water inside the cells is less than outside, so water will flow into the cells.
Cells living in salt water will find that the water in their cells will want to leave. The concentration of plain water is higher in the cells, so the water will leave the cells to try and “even it out”.

6. Why is the flow of water important?
Because water flows easily through membranes, organisms living in fresh water have to make sure that they don’t get bloated and explode from too much water.
Organisms living in salt water have to make sure that all the water in their bodies doesn’t flow out to salt water that they live in

7. Osmoregulation
Marine and freshwater organisms must take great care to maintain a proper balance of water and salt in their bodies.
Some organisms have highly developed kidneys – some have special salt excretion glands – some have special excretory systems that retain water and excrete urine as paste!!!!!
This process of maintaining a balance is called osmoregulation

8. Organisms to think about…
Freshwater snails
(what stops the
surrounding fresh
water from moving
into their bodies?)

9. Organisms to think about…
Lobsters
(What stops the
water in their
bodies from
flowing out to
the surrounding
salt water??)

10. Organisms to think about…
Salmon (they live in fresh and salt water!!!)

11. Plants to ponder???
Obviously this lab activity is not about salmon or snails or lobsters
So… what does osmosis have to do with plants???
Your conclusion should talk about how osmosis affects plants and their ability to thrive and survive