Biology Review for the GHSGT

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