1. Biology Review for the GHSGT
The Cell Membrane
and Cellular Transport

2. Solutions
A solution is a liquid mixture of solute dissolved in solvent
Example: Salt water is a solution.
Salt (the solute)
Is dissolved in water (the solvent)

3. Maintaining Homeostasis
Keeping an ideal balance of solutes within the cell
Cytoplasm must keep it’s watery-jelly like substance (solvent) in the right balance with solutes such as salt and other minerals

4. Hormones Chemical messengers that regulate body functions
Maintain homeostasis
Movement of oxygen/carbon dioxide
Maintain internal temperature
Regulation of fluids across cell membrane

5. Cell Membrane
Main Purpose: regulate the movement of materials into and out of the cell
Is semi-permeable (selectively permeable)- only certain substances can go through
Has a phospholipid
bilayer

6. Passive Transport
Molecules move spontaneously through the cell membrane from areas of higher concentration to areas of lower concentration.
Moves “with the concentration gradient”
Automatic, doesn’t not require energy
Three types: diffusion, facilitated diffusion, osmosis

7. Diffusion
Diffusion - process by which substances move directly through the cell membrane
Facilitated diffusion- involves the help of carrier proteins
For molecules too large to fit between the phospholipids

8. Osmosis
The movement of water from an area of high concentration to an area of low concentration through a semi-permeable membrane
Essentially, osmosis is the diffusion of water
Can occur in either direction, depending on solution concentrations
Could be hypertonic, hypotonic, or isotonic

9. Types of Solutions
Hypertonic- particle concentration is higher in the solution than in the cell.
Water goes out
Cell shrinks

10. Types of Solutions
Hypotonic – particle concentration is lower in solution than in the cell
Water goes into cell
Cell swells

11. Types of Solutions
Isotonic- particle concentration is the same outside and inside the cell
Same amount of water goes in as goes out

12. Types of Solutions

13. Activity – What will be the effect on the cell?
1. Internal cellular solution concentration of 11.4 mg/L placed in a solution with 9.9 mg/L.
2. Internal cellular solution concentration of 1.1 mg/L placed in a solution with 4.4 mg/L.

14. Activity – What will be the effect on the cell?
3. Internal cellular solution concentration of 0.01 mg/L placed in a solution with 0.1 mg/L.
4. Internal cellular solution concentration of 6.81 mg/L placed in a solution with 6.69 mg/L.
5. Internal cellular solution of 8.03 mg/L placed in a solution with 2.21 mg/L.

15. Active Transport
For movement against the concentration gradient (low to high)
Requires energy
Movement is characterized by it’s direction
exocytosis or
endocytosis

16. Exocytosis Removes materials from the cell
Waste materials, proteins, and fats
Uses a storage sac to move materials toward membrane, membrane opens up, and materials are expelled out from the cell

17. Endocytosis
Brings materials into the cell without passing through the cell membrane
The membrane folds itself around the substance, creating a vesicle, and brings the substance into the cell
How Amoebas eat

18. Fill in the Blank
1. A cell which has no net gain or loss of water is in a(n) __________ solution.
2. The process of expending energy to move molecules across a membrane is __________ transport.
3. A plant cell that has swelled to its limits is referred to as a ________ solution; a shrunken plant cell is a __________solution.

19. Choose the best answer
1. the movement of substance into and out of a cell without the use of energy is called:
A. active transport
B. passive transport
C. exocytosis
D. endocytosis

20. Choose the best answer
2. The movement of water across a semi-permeable membrane from an area of high water concentration to an area of low water concentration is called:
A. active transport
B. diffusion
C. osmosis
D. hypotonic

21. Choose the best answer
3. A type of membrane which allows only certain molecules to pass through is called:
A. permeable
B. semi-permeable
C. active
D. porous

22. Choose the best answer
4. A cell placed in a solution shrinks by the process of osmosis. What kind of solution is outside the cell?
A. hypotonic
B. hypertonic
C. active
D. isotonic

23. Choose the best answer
5. If the solution surrounding a cell has a lower concentration of solutes than inside the cell, water will move into the cell through osmosis, causing it to expand. What kind of solution is surrounding the cell?
A. active
B. passive
C. hypertonic
D. hypotonic

24. Short Answer 6. How does active transport differ from diffusion?
7. Dried beans are soaked overnight in preparation for cooking. Explain the process affecting the beans. What will happen to the dried beans?
8. Describe the difference between exocytosis and endocytosis.
9. A celery stalk is placed in a solution. It begins to wilt. What is a likely component of that solution?

25. From American Book Company’s Passing the High School Graduation Test in Science
by Liz Thompson and Michelle Gunter