Answer the following questions, then use the Submit button on the right to turn in your work.

  1. Explain what a concentration gradient is  and what it means for a molecule to diffuse down the concentration gradient.
  2. Explain why facilitated diffusion does not require energy from a cell.
  3. How are receptors and transport proteins similar?
  4. When a person becomes dehydrated due to the loss of fluids and solutes, a saline solution (water and salts) is infused into the bloodstream by medical personnel. Why is saline solution used instead of pure water?