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Name: __________________________________________________
Unit 4 Homeostasis and Cell Transport
Period: ________
1
I. Passive Transport
- homeostasis = maintenance of a __________________________________________ even though
environmental conditions are constantly changing
- cell membranes __________________________________________ by controlling what enters and
leaves the cell
- passive transport = process by which some substances ________________________________________
__________________________
A. Diffusion – the net __________________________________________________________________
_________________________________________________________________________________
- Occurs because of the _______________________________ in molecules (random movement)
B. Diffusion in Water
Why does the food dye diffuse? Food dye slowly diffuses b/c ____________________________
______________________________________________________________________________
C. Diffusion in air
Why does the smell diffuse? The odor molecules ______________________________________
and the gas molecules in the air and slowly diffuse into the classroom.
D. Concentration Gradient –
__________________________________________________________
E. Dynamic Equilibrium –
the condition in which there is _____________________________________________________
- This means there ___________________________________________________________
i. there is no ___________________________________________ – everything is equal
ii. Draw dynamic equilibrium in a glass with a solute…
Unit 4 Homeostasis and Cell Transport
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F. Osmosis – the _____________________________________________________________________
_________________________________________________________________________________
- Diffusion of water goes from ____________________
_____________________________________________
http://www.youtube.com/watch?v=sdiJtDRJQEc&feature=related
Which way will the water move:
Which way will the water move:
Cell
Sucrose = 65%
Water = 35%
Solution
Sucrose = 75%
Water = 25%
Cell
Sucrose = 25%
Water = 75%
Unit 4 Homeostasis and Cell Transport
Solution
Sucrose = 35%
Water = 65%
3
Unit 4 Homeostasis and Cell Transport
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1. Solution –
a. Example:
2. Solute 3. Solvent –
a. What is the most common solvent? ___________________________
4. Isotonic Solution –
a. Would osmosis occur in this situation?
5. Hypotonic Solution –
a. Which way will the water move?
6. Hypertonic Solution –
a. Which direction will the water move?
7. Turgor Pressure –
a. High turgor pressure can cause
animal cells to burst. Why?
b. What would happen if there is
low turgor pressure in plants?
Unit 4 Homeostasis and Cell Transport
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Unit 4 Homeostasis and Cell Transport
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MB: p. 95-100
BDOL: p. 195-198
1. Look at the U-shaped tube in the figure. Why did the number of water molecules on each side of the
membrane change after osmosis, whereas the number of sugar molecules stayed the
same?____________________________
________________________________________________________________
________________________________________________________________
________________________________________________________________
________________________________________________________________
2. How does the plasma membrane of a cell compare with the membrane in the U-shaped tube?
___________________________________________________
________________________________________________________________
_______________________________________________________________________________________
_________________________________________
3. Explain the behavior of molecules in an isotonic solution. _________________
_______________________________________________________________________________________
_______________________________________________________________________________________
__________________
_______________________________________________________________________________________
_________________________________________
4. Does osmosis occur if a cell is placed in an isotonic solution? Explain. ______
_______________________________________________________________________________________
_______________________________________________________________________________________
__________________________________________________________________________________
5. Why does water enter a cell that is placed in a hypotonic solution?__________
_______________________________________________________________________________________
_______________________________________________________________________________________
__________________________________________________________________________________
6. What happens to the turgor pressure inside a plant cell that is placed in a hypertonic solution?
________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
__________________________________________________________________________________
7. What can happen to animal cells exposed to hypotonic solutions? What mechanism have some protests
evolved for living in a hypotonic environment?
_______________________________________________________________________________________
_______________________________________________________________________________________
__________________
8. What causes a plant to wilt? _______________________________________
________________________________________________________________
Unit 4 Homeostasis and Cell Transport
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8. Contractile Vacuoles –
a. Uses ____________
b. Usually found in unicellular _________________________
c. This prevents them from bursting in a _________________________.
9. Plasmolysis –
a. What happens to a plant during plasmolysis?
i.
ii. The plants plasma membrane and cytoplasm _________________________________
_________________________________________
10. HYPOTONIC / HYPERTONIC – REVIEW
a. What will happen to an Elodea Leaf in a hypertonic solution?
i. Water will _____________________________________
ii. Which is called _____________________, which will cause the plant leaves to
______________
b. If we put Elodea leaves in a hypotonic solution, what happens?
i. Water will ________________________________
ii. …which will cause the cell to ___________________. If it’s an animal cell it
will….______________________, UNLESS the cell has a
________________________to pump the water out.
Unit 4 Homeostasis and Cell Transport
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Brief Review (summary):
1. Define the following terms in your own words:
A. Osmosis-_____________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
B. Hypotonic Solution- ___________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
C. Hypertonic Solution- __________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
D. Isotonic Solution- _____________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
2. In a hypotonic solution, how will water molecules move? _______________________________________
_______________________________________________________________________________________
3. In a hypertonic solution, how will water molecules move? ______________________________________
_______________________________________________________________________________________
4. In an isotonic solution, how will water molecules move? _______________________________________
_______________________________________________________________________________________
5. Explain how hypotonic conditions can make a plant become rigid. ________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
6. Explain how hypertonic conditions can make a plant wilt. ______________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
Unit 4 Homeostasis and Cell Transport
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11. Selective Permeability –
a. Why is selective permeability important?
i. So the cell can allow important substances
_____________________________________and keep harmful substances out, like
________________________.
12. Passive Transport –
a. This process uses ___________________
b. Molecules moving from _________________________________________
13. Facilitated Diffusion –
a.
b. Example:
i. Glucose going from ______________________
outside the cell to ________________________
inside the cell
This is a ____________________
c. Why doesn’t this need energy?
i. Because it’s still along the _______________________
14. Comparison of Diffusion and Facilitated Diffusion
Unit 4 Homeostasis and Cell Transport
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15. Carrier proteins –
proteins that assist _________________________________________________
16. Ion channels –
a. proteins transport ions from ____________________________________________________
b. ________ like Na+, Ca+, etc _______________________________________, so they must
travel through proteins channels
c. ____________________________________________________________________
d. Some channels are always open, some have gate
e. Gates open from ___________________: stretching of cell membrane, electrical, or chemical
signals
17. Active Transport –
- transport of materials _________
__________________________
__________________________
__________________________
18. ATP (adenosine tri-phosphate) –
a. the _______________________________ for
the cell
b. Breaks down from ATP  ADP (Adenosine diphosphate)
c. Hydrolysis of the phosphate ________________
________________
19. Sodium-potassium Pump –
a. Transfer protein example
b. _____________________________________________________________
c. Creates electrical gradient which is important for ____________________________
Unit 4 Homeostasis and Cell Transport
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20. Endocytosis –
a. when a cell ________________________________
_______________________ from the environment
b. __________________________
21. Pinocytosis –
Transport of ________________ into the cell
22. Phagocytosis –
Transfer of ________________________________________________________________________
a. Phagocytes – Cells that _______________________________________________________
___________________________________________________________________________
http://www.youtube.com/watch?v=1w10R9lv7eQ
23. Exocytosis –
a. when a cell _________________________________________________________________
___________________________________________________________________________
b. Cell exports __________________________________________________________ this way
c. This process uses _____________
Unit 4 Homeostasis and Cell Transport
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Extra Stuff:
Unit 4 Homeostasis and Cell Transport
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