Diffusion, Osmosis, and Active Transport (Biology Lab Report)

Big Question: What factors affect the motion of molecules into and out of cells, a process known as diffusion?

After looking at the path taken by several red dye molecules, their motion can best be described as:

  1. Moving in a directed way from high to low concentration
  2. Moving randomly through collisions in no particular direction
  3. Staying close to the other dye molecules
  4. Moving in clumps of molecules together

2.It is often stated that substances diffuse from highly concentrated areas to areas of low concentration. Describe how this works if a molecule can’t tell that it is in a region of high concentration and just diffuses randomly through collisions. (2pts)

  1. My Hypothesis: If the concentration of a gas such as oxygen is HIGHER outside the cell, then molecules of oxygen will ________________

4.Set up the model so that there is a high concentration of something outside and a low concentration of that same thing inside. What are the chances that a molecule will move into or out of the cell:

  1. There is a greater chance that a molecule will move from the lower concentrated area to the higher concentrated area.
  2. There is a greater chance that a molecule will move from the higher concentrated area to the lower concentrated area.
  3. There is a equal chance that a molecule will move in either direction.

5.Describe the flow of molecules when there is an area of high and low concentration.

  1. Molecules move from the side with high concentration to low concentration.
  2. Molecules move from the side with low concentration to high concentration.
  3. Both a and b, but there is a greater flow from high and low concentration than low to high concentration.
  4. The flow will be equal in both directions regardless of the starting concentrations.
6.What is true of the concentrations when equilibrium has been reached?

A.       They will be higher inside the cell.

B.       They will be higher outside of the cell.

C.       They will reach a minimum inside and outside.

D.       They will be the same inside and outside.


7.What is true of the rate at which molecules move into and out of the cell at equilibrium?

A.       More move into the cell than out of it.

B.       More move out of the cell than into it.

C.       Equal amounts move into and out of the cell.

They move randomly, so it is not predictable.

8.What happens to the oxygen concentration of the cell when you move it to a new environment?

  1. It stays the same.
  2. It goes up.
  3. It goes down.
  4. It goes up or down until reaches equilibrium

9.Explain how a red blood cell delivers oxygen from your lungs to the rest of your body.  (2pts).


10.Describe what happens when the red blood cell contains hemoglobin:

  1. It is the same as without hemoglobin.
  2. It speeds up the normal diffusion.
  3. It causes the concentration of oxygen to be higher inside the cell
  4. It causes the oxygen concentration to be higher outside the cell when equilibrium has been reached

11.Explain how hemoglobin helps transport more oxygen than could normally be done with simple diffusion (2pts):

  1. How does surface area affect diffusion rates? (2pts) Hint: this question is also on the simulation.
  1. Single-celled organisms absorb everything they need directly through their “skin,” their cell membrane. However, you could never get enough oxygen if oxygen could only diffuse through your skin. Explain why it is necessary to have lungs with large surface areas (2pts):
  1. Writing Wrap Up (9pts): Use the words diffusion, high concentration, low concentration, energy, surface area, lungs, red blood cells, hemoglobin, and oxygen in a few sentences to show that you know what each words means in the context of the lab. Please use a different color text, highlight or bold the vocabulary words in your paragraph.