assignment # diffusion and osmosis mrs. mccarthy biology november 30, 2015
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I. The Cell
A. In order to live, a cell must take in nutrients and water and eliminate wastes
B. Parts of the cell involved in diffusion and osmosis:
1. Cell membrane – a semipermeable membrane that allows some small molecules through, but blocks others. Water is able to pass through freely.
I. The Cell
2. Cytoplasm – the jelly like substance in the cell that is composed of mainly water and dissolved solutes.
II. The movement of Substances Into and Out of Cells
A. Diffusion is the movement of molecules from an area of greater concentration to an area of lesser concentration
1. Diffusion stops when equilibrium (balance) is reached
Diffusion causes the molecules to move from an area of high
concentration to an area of low concentration
II. The movement of Substances Into and Out of Cells
B. Osmosis is the diffusion of water across the cell membrane
1. The water will move from an area of low solute to an area of high
solute until equilibrium is reached. (The water wants to evenly dilute the solute)
III. Types of solutions
A. Hypertonic – the concentration of solutes outside the cell is greater than it is inside.
1. Water will move outside the cell to dilute the higher concentration of solutes
2. The cell will shrink
IV. Models of Different Solutions (turn to the back)
A. A cell in a HYPERTONIC SOLUTION
X = NaCl (salt)
O = H2O
X X
X X
X
X
X X
X X
X X
X
X
XXOO
O
O
O
OO
OO
O
III. Types of solutions
B. HypOtonic – the concentration of solutes inside the cell is greater than it is outside
1. Water will move inside the cell to dilute the higher concentration of solutes
2. The cell will SWELL (unless the water is pumped out by a contractile vacuole)
IV. Models of Different Solutions (turn to the back)
A. A cell in a HYPOTONIC SOLUTION
X = NaCl (salt)
O = H2O
X
X
X
XXX
XX
X
X
OO
O
O O
O
OO
OO
OO
OO
O
O
The contractile vacuole in single celled organisms pumps out excess
water so the cell does not burst
III. Types of solutions
C. Isotonic – the concentration of solutes inside and outside the cell is the same
1. Water will not move
2. The cell will stay the same
IV. Models of Different Solutions (turn to the back)
A. A cell in a ISOTONIC SOLUTION
X = NaCl (salt)
O = H2O
X
X
X
X
X
OO
O
O
O
X
X
X
X
X
OO
O
O
O
Journal Entry #1. Explain the difference between osmosis
and diffusion.
2. Explain this cartoon using the terms osmosis, hypertonic, and diffusion.
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