Assignment #Diffusion and Osmosis

Mrs. McCarthyBiology

April 22, 2023

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.

The Cell Membrane

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 CellsA. Diffusion is the movement of molecules

from an area of greater concentration to an area of lesser concentration1. Diffusion stops when equilibrium (balance) is reached

Diffusion causes the molecules to move from area A to area B

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 CellsB. Osmosis is the diffusion of water across

the cell membrane1. 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)

In osmosis, the water will move towards the solute to dilute it

evenly.

Osmosis

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 solutes2. The cell will shrink

Hypertonic Solution

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 outside1. Water will move inside the cell to dilute the higher concentration of solutes2. The cell will SWELL (unless the water is pumped out by a contractile vacuole)

HypOtonic solution

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

OOO

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 same1. Water will not move2. The cell will stay the same

Isotonic solution

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

XOO

O

OO

X

X

X

X

XOO

O

OO

Journal Entry #1. Explain the difference between osmosis

and diffusion.2. Explain this cartoon using the terms

osmosis, hypertonic, and diffusion.

Classwork

Complete the Diffusion and Osmosis practice worksheet. Be sure to read all directions very carefully.