Download Chapter 3 Review Questions

Cell Transport Review Sheet.
Part I – Label the following:
A. glycolipid
B. glycoprotein
F. hydrophobic tails
G. hydrophilic heads
H. bi-layer
C. integral protein
D. cholesterol
E. peripheral protein
Part II – Fill in the blank
1. The process of diffusion causes molecules to move from (low to high or high to low)
concentrations until a state of ____equilibrium________________ is reached.
2. The diffusion of water is known as ___osmosis_______________.
3. __Facilitated______________ diffusion uses proteins to bring materials into the cell from
high to low concentration, requiring no cell energy.
4. Diffusion, osmosis and facilitated diffusion are all examples of __passive___________
transport, in which the cell does not need to use any energy.
5. During active transport molecules move from an area of _low___ concentration to an
area of ___high_________ concentration.
6. ___Exocytosis______ is a form of active transport in which the cell sends materials out
of the cell using vesicles, small storage structures that fuse to the cell membrane.
7. ____Endocytosis______ is the reverse of the process named in # 6. The cell membrane
wraps around a substance to be brought into the cell forming a vesicle around it.
8. There are two types of endocytosis: ___phagocytosis__________ which involves
bringing solids or large molecules into the cell, and ___pinocytosis_________, which
deals with bringing liquids or very small molecules into the cell.
9. In the pictures below each “X” represents a molecule of water. In each diagram indicate
which direction water will be moving (mostly in, mostly out, or equally in and out).
XXXXX
A.
XXXXX
equally in/out
XXXXX
B. Mostly out
XX
XXXXX
XXXXX
XXXXX
C. Mostly in
10. Look at each of the pictures below. Identify whether the picture represents a plant cell in
fresh water (isotonic), distilled water (hypotonic) or salt water (hypertonic).
A.salt water
B.fresh water
C. distilled water
Hypertonic
Isotonic
Hypotonic
11. Look at each of the pictures below. Identify whether the picture represents a blood cell in
fresh water, distilled water or salt water. It’s hard to see these shapes in black and white,
color versions below are easier.
A. Fresh water (isotonic)B. distilled water (hpotonic) C. salt water (hyertonic)
12. Why did the potato left in salt water or fresh water lose or gain water? What was
different about the amount of water inside and outside the cell, and what state were the
potato cells trying to reach?
Potato in fresh water was surrounded by a hypotonic (low solute/high water) environment
therefore water entered the potato from the beaker. Potato in salt water was surrounded
by a hypertonic environment (high solute/low water) therefore water left the potato and
entered the beaker.
The potato cells were trying to reach equilibrium with the surrounding solution, whether
it be salt water or just regular tap water.
13. How do facilitated diffusion and active transport differ? Is osmosis an example of facilitated
diffusion or active transport?
Facilitated diffusion is passive (requires no energy, uses a protein, moves from high to low)
Active transport uses a protein that requires energy (moves from low to high).
Osmosis is an example of facilitated diffusion (when entering a cell) if you consider that
water uses an aquaporin to move in or out of the cell from high to low concentrations.
The aquaporin does not require ATP (energy).
14. Compare a cell from a unicellular organism with a cell from a multicellular organism in
terms of cell specialization.
Unicellular organisms like bacteria (prokaryotes) are not specialized; they must be able to
perform all life functions from the single cell that they consist of. Animal cells/Plant
cells (eukaryotes) are specialized to perform different functions. Cells in eukaryotes
form tissues, then organs then organ systems. These specialized cells have unique
structures and functions (e.g. nerve cells, heart cells, lung cells, blood cells, etc).
15. What is the function of active transport in moving small molecules and ions across cell
membranes?
Active transport applies to cases where the cell must move molecules up or against a
concentration gradient from low to high concentration.
16. Explain how diagrams A and B below relate to osmosis. Be sure to discuss how tonicity
relates to the movement of water. Also, state which side of the tube is
hypertonic/hypotonic.
Tube A and diagram B show that sugar molecules are not able to pass through the
semipermeable membrane in the middle of the tube. The only substance that can pass is
the water. In this case the diffusion of the water must be osmosis since sugar is trapped.
Tonicity is describing the water and solute concentration within a solution. Based on
these concentrations relative to another solution (for instance within a cell), a prediction
can be made about the direction of water movement from high to low concentrations
(osmosis) from one solution to another.
The right side of the tube is high solute, low water, making it hypertonic. The left side is
low solute, high water making it hypotonic. Water will move from the left to the right,
changing the water levels as shown.