1. Warm-Up (11/03)
Answer the following questions, and explain in a complete sentence why each answer is correct.
What happens during diffusion?
A. Particles move from an area that is more concentrated to an area that is less concentrated.
B. Particles move from an area that is less concentrated to an area that is more concentrated.
C. Particles move slightly but stay in almost the same place.
D. Particles move to different areas but always return to their starting point.
The structure of the phospholipid bilayer is composed of _________________
Hydrophobic heads on the outside and hydrophilic tails on the inside.
Hydrophilic heads on the outside and hydrophobic tails on the inside.
Hydrophobic heads on the inside and hydrophilic tails on the outside.
Hydrophilic heads on the inside and hydrophobic tails on the outside.

2. Concentration Gradient
High concentration
Low concentration

3. Concentration Gradient
Diffusion – movement of particles across a membrane from high to low concentration
Osmosis – movement of water across a membrane
high
low
low
low
low

4. Osmosis

5. Gummy Bear Lab
Write your prediction about the size of the gummy bear for each solution on a piece of paper next to your cup.
If the solution is hypotonic, I predict ________________.
If the solution is hypertonic, I predict ________________.
If the solution is isotonic, I predict ________________.

6. Closure Answer the following question in a complete sentence:
Name
Date
Period
Explain why does a gummi bear shrink in a hypertonic solution and get bigger in a hypotonic solution.
A gummy bear shrinks in a hypertonic solution because ____________ and gets bigger in a hypotonic solution because ______________.
Scale from 1-10