Biology Review for the GHSGT

The Cell Membrane

and Cellular Transport

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)

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

Hormones

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

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

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

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

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

Types of Solutions

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

Types of Solutions

Hypotonic – particle concentration is lower in solution than in the cell Water goes into cell Cell swells

Types of Solutions

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

Types of Solutions

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.

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.

Active Transport

For movement against the concentration gradient (low to high)

Requires energy

Movement is characterized by it’s direction exocytosis or endocytosis

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

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

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.

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

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

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

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

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

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?

From American Book Company’s Passing the High School Graduation Test in Science

by Liz Thompson and Michelle Gunter