Presentation on theme: "Agenda: Feb 13, 2015 1)ET #51: Why do you smell odors when you are not necessarily right next to the source? 2)Review Cell Division 3)Explain 28: Osmosis."— Presentation transcript:
Agenda: Feb 13, 2015 1)ET #51: Why do you smell odors when you are not necessarily right next to the source? 2)Review Cell Division 3)Explain 28: Osmosis Activity https://www.youtube.com/watch?v=SSS3EtKAzYchttps://www.youtube.com/watch?v=SSS3EtKAzYc https://www.youtube.com/watch?v=SrON0nEEWmo 4) Homework: Complete Osmosis HW? Test Review due Tuesday/ Wednesday after break. Test 2/26 & 2/27; SCaR-NONE Learning Goal:1) I can explain the process of diffusion & osmosis and how it’s important to cells. Thinking Skills: Problem solving, main idea Habits of Mind: persisting Have your Cell Division packet on edge of desk! Thanks! Computers ON!
ET #51: Why do you smell odors when you are not necessarily right next to the source? http://slideplayer.com/slide/754058/http://slideplayer.com/slide/754058/ good ppt of osmosis/diffusion
Scientifically speaking, what’s wrong with this Garfield picture? RED Let’s quickly and quietly get a RED pen out and log on to the computer. Go to the public/all/kmchenry folder and grade your Cell Division paper, making corrections as needed. You have SEVEN minutes! Work quickly!
12. What is the “Big Idea” here? Water moves into or out of the eggs depending on the concentration of water inside vs. outside. = moves from High to Low
Solute: “The dissolved substance in a solution” Example: Saltwater Saltwater is the solution, Salt is the solute Water is the solvent Draw different solutes by using different symbols. = water = sugar = salt Example:
One solution has a lower concentration of solute than another. One solution has a higher concentration of solute than another. Both solutions have same concentrations of solute.
There are microscopic pores in the membrane. Molecules below a certain size can diffuse through the pores. Water molecules can easily diffuse through the pores. In the next slides represents a water molecule and represents a sugar molecule 5
membrane watersugar solution There are as many water molecules on the right as there are on the left but many of them are attached to sugar molecules and are not free to move. 6
Because there are more freely moving water molecules on the left, more diffuse through the pores of the membrane from left to right than from right to left. 7 Molecular movement
Because the membrane allows only molecules of a certain size to diffuse through it, it is called selectively permeable. The cell membrane functions as a selectively permeable membrane. The cell sap and cytoplasm function as fairly concentrated solutions. 9
The scale of the following drawings is greatly distorted. Even if the cells were as large as they appear on the screen, the molecules would still be invisible particles 10 Scale of drawings
There is a greater concentration of free water molecules outside the cell than inside so water diffuses into the cell by osmosis and the cell swells up Osmosis in animal cells 11
If osmosis continued the animal cell would burst This would be bad news for animals Consequently there are processes in the animal’s body which control osmosis Mainly, this is done by keeping the concentration of body fluids outside the cell the same as it is inside 12
In fresh water fish, the blood is more concentrated than the surrounding water As a result the fish takes in water by osmosis Not so much through the skin, which is thick, but through the gills which have a very thin membrane Trout Fresh water fish 14
The fish gets rid of the excess water by means of its kidneys Perch gills absorb water by osmosis blood carries water to kidneys kidneys expel excess water......in the form of dilute urine heart 14
Sea water is a more concentrated solution than the fish’s blood. What will be the osmotic effect ? A sea water fish will lose water by osmosis through its gills. The fish drinks sea water and the gills expel the excess salt from the blood, so keeping its concentration constant Herring Sea water fish 15
In a plant cell, the cell membrane acts as a selectively permeable membrane The vacuole contains a solution of salts and sugars If there is water outside the cell, it will diffuse by osmosis into the vacuole The cell wall is freely permeable to water The vacuole will expand, pushing the cytoplasm outwards against the cell wall 16
The cellulose cell wall cannot stretch, so the vacuole cannot continue to expand But the pressure of the vacuole against the cell wall makes the cell very firm A plant cell in this condition is said to be turgid If all the cells in the plant are turgid, the plant will be firm and upright and the leaves would be expanded 17
cell wallcytoplasm and cell membrane vacuole The cell absorbs water by osmosis........but the cell wall stops the cell expanding any more Plant cells 18
These cells are short of water; the tissue is limp and the plant is wilting The cells have taken up water by osmosis; the cells are turgid and the tissue is firm Limp and turgid tissue 21