Download Membrane Function - NMSU Instructure

Biol 211. Extra Practice & Review
Membrane Function
1. What factors influence whether and how a solute will cross a membrane?
2. What are the properties of solutes that can cross a membrane by simple diffusion?
3. Can O2 cross a membrane by simple diffusion UP its concentration gradient? Explain your
answer.
4. What is the difference between simple and facilitated diffusion?
5. Which type of transport protein binds its solute as the solute is moving down its
concentration gradient? Which type of transport protein uses energy as it moves the solute
up its concentration gradient?
6. What is active transport? How is it different than facilitated diffusion? Does it share any
similarities with facilitated diffusion?
7. Be sure you can re-create the table we made in class (passive vs active transport: energy
required, direction of solute movement, and some examples of each).
8. What is osmosis?
9. What will happen to a cell placed in a hypertonic solution?
10. What will happen to a cell placed in a hypotonic solution? What about if that cell is a plant
cell?
(remember, hypertonic and hypotonic solutions refer to the solute concentration in a solution
surrounding a cell, relative to the solute concentration in the cell’s cytoplasm)
11. Compared to your cells, an isotonic IV saline solution has a solute concentration that is
________________. [higher, lower, the same as]
12. What would happen if you used an IV saline solution that was hypertonic relative to your
cells?
13. Which type of transport is used to transport LDL into cells from the circulation?
14. How does insulin get secreted from the pancreatic cells that make it? Why can’t insulin be
exported by say simple diffusion?
15. Why can over-fertilizing a plant (with fertilizer that contains a high concentration of
solutes such as nitrates) cause it to dehydrate? Be specific!
16. A mutation in the gene that encodes the LDL receptor can prevent the receptor from
localizing in the cell membrane. What will be the consequences for a person who has both
alleles of their LDL receptor gene mutated in this way? Explain your answer.
Clicker Questions
Figure 5.13 is an example of
a. simple diffusion
b. facilitated diffusion
Hold Figure 5.13 upside down- now what is it an example of?
a. simple diffusion
b. facilitated diffusion
In facilitated diffusion, the direction of solute movement is
a. into the cell
b. out of the cell
c. down its concentration gradient
d. up its concentration gradient
Can ions cross a membrane by simple diffusion?
a. yes, b/c they are small
b. yes, b/c they are hydrophobic
c. no, b/c they are hydrophilic
(so what determines their ability to cross a membrane?)
Which require(s) a transport protein?
a. simple diffusion
b. facilitated diffusion
c. active transport
d. all of them
e. b and c
If INTRACELLULAR solute concentration is high, which way will water flow by osmosis?
a. into the cell
b. out of the cell
c. no net movement of water
What prevents a plant cell from bursting in a hypotonic solution?
a. the glycogen cell wall
b. the cellulose cell wall
c. the protein cell wall
d. the stabilizing cholesterol in its membrane
When a cell is in a hypertonic solution, water will move
a. into the cells
b. out of the cells
c. it won’t
What is osmosis?
a. movement of solutes
b. movement of solutes to lower concentration areas
c. movement of water to lower solute concentration
d. movement of water to higher solute concentration