Osmosis and Diffusion Practice
I.
Name:
Based on what you’ve learned, in your own words, answer the following questions regarding movement of
materials through a cell membrane.
1. What does semi-permeable mean?
2. What is the net movement of molecules from high to low concentrations?
3. What is the term for the diffusion of water?
4. What does dynamic equilibrium mean?
5. What is a hypertonic solution?
6. What is a hypotonic solution?
7. What is an isotonic solution?
II.
Observe the diagrams in the table below. Assume that the dots are dissolved small non-polar particles on
either side of the cell membrane. They are like oxygen molecules that can go across the membrane. Do
the following situations represent concentration gradients? If so, in which direction would diffusion
occur? Draw arrows from the appropriate molecule to represent the movement.
Gradient?
Yes or No
Net movement
left, right, or
none
Yes
Right
Gradient?
Yes or No
Net movement
left, right, or
none
Yes
Left
Gradient?
Yes or No?
Net movement
left, right, or
none
No
None
III.
Observe the diagrams in the table below. Assume that the dots are dissolved particles (like
protein or carbohydrate molecules) on either side of the cell membrane. Do the following situations
represent concentration gradients? If so, in which direction would osmosis occur? = water,
=
dissolved particle. Again, use arrows to show the movement of the appropriate molecules.
Gradient?
Yes or No
Yes 1free
water
molecule:5fwm
Gradient?
Yes or No
Yes 7:1
Gradient?
Yes or No?
No. 3:3
Net
movement
left, right, or
none
Left (2
water)
Net
movement
left, right, or
none
Right (3
water)
Net
movement
left, right, or
none
None
IV.
Observe the table below. Are the following hypotonic, hypertonic, or isotonic solutions? Which way will water
mostly move? (some situations may have water moving equally)
intracellular fluid
(inside the cell)
5% salt
10% salt
3% glucose
2% protein
9% salt
13% water
59% water
90% water
74% glucose
extracellular fluid
(outside of the cell)
10% salt
10% salt
1% glucose
1% protein
9% salt
25% water
45% water
92% water
87% glucose
Hypotonic, Hypertonic,
Isotonic
Hypertonic
Isotonic
Hypotonic
Hypotonic
Isotonic
Hypotonic
Hypertonic
Hypotonic
Hypotonic
water moves mostly
inside or outside the cell
outside
inside
inside
inside
outside
inside
inside
50% Salt Solution
V.
Observe the diagram and answer the questions. The boxes represent
different solutions the same cell is placed in.
Hypertonic
1. Label the boxes hypertonic, hypotonic, or isotonic.
1 0%
salt
2. What will happen to the cell if it is placed in a 50% salt solution? (draw
arrows showing water’s net movement)
Cell will shrink as water moves out to equalize the free water molecule concentration
on both sides of the membrane.
3. What will happen if the cell is placed in pure water? (draw arrows
showing water’s net movement)
Cell will swell as water moves out to equalize the free water molecule concentration on
both sides of the membrane.
Pure Water
Hypotonic