Mandatory Experiments

To Prepare and Examine a Plant Cell:

Procedure:

Preparing the Slide

1. Using a knife, cut one segment of an onion and peel away a small layer of cells using forceps.

2. Place the layer of cells on a slide and put a drop of iodine to dye the cells to improve visibilty.

3. Place a coverslip to protect the cells and prevent them drying out by placing it at 45^o angle above the slide and gently lowering it with either a mounted needle or forceps to prevent air bubbles.

Examining the Specimen

1. Place the slide onto the stage of the microscope and secure it with the stage clips.

2. View the slide with the lowest power objective lens first, to know where to focus on with the high power lenses.

3. Ensuring that the cells are in your field of view, go to the higher power objective lens to see it in greater detail.

4. Then use the high power objective lens to see it in full detail. (Be careful as the high power objective lens is close to the slide so it may damage it if mishandled.)

Diagram:

To Prepare and Examine an Animal Cell:

Procedure:

Preparing the Slide

1. Use a cotton swab to swab your cheeks to collect cheek cells.

2. Smear the cells onto the slide.

3. Place methylene blue to dye the cells to improve visibilty.

4. Place a coverslip to protect the cells and prevent them drying out by placing it at 45^o angle above the slide and gently lowering it with either a mounted needle or forceps to prevent air bubbles.

Examining the Specimen

1. Place the slide onto the stage of the microscope and secure it with the stage clips.

2. View the slide with the lowest power objective lens first, to know where to focus on with the high power lenses.

3. Ensuring that the cells are in your field of view, go to the higher power objective lens to see it in greater detail.

4. Then use the high power objective lens to see it in full detail. (Be careful as the high power objective lens is close to the slide so it may damage it if mishandled.)

Diagram:

To Demonstrate Osmosis:

Procedure:

1. Soak two pieces of visking tubing of the same length to soften and make them pliable.

2. Tie a knot at one end of both of the tubes.

3. Dissolve a large amount of sucrose in warm water in a beaker to form a concentrated sucrose solution.

4. Fill one of the tubes with a measured amount of distilled water.

5. Fill the second tube with the exact same amount of sucrose solution as the distilled water.

6. Dry each tube and note its turgidity and record its mass.

7. Place each tube in beakers of distilled water of identical amounts.

8. Leave the tubes for 30 minutes.

9. Remove the bags, dry them and note their turgidity and record their mass.

10. Record the results of the mass at the start, the final mass, and the change in turgidity.

Diagram:

To Test for a Reducing Sugar:

Procedure:

1. Label two test tubes A and B.

2. Place glucose into tube A.

3. Place an equal amount of water in tube B.

4. Add the same volume of glucose and water of Benedict’s solution to each test tube.

5. Place the test tubes in a water bath at 80-100OC for 5-10 minutes.

6. Swirl the test tubes and note any colour changes.

7. Record results in table.

Diagram:

To Test for Starch:

Procedure:

1. Label test tubes A and B.

2. Place starch solution into tube A.

3. Place an equal amount of water in tube B.

4. Add 2-3 drops of iodine solution to both tubes.

5. Swirl the tubes and note any colour change.

6. Record results in table.

Diagram:

To Test for Protein:

Procedure:

1. Label test tubes A and B.

2. Place milk into tube A.

3. Place an equal amount of water in tube B.

4. Place an equal amount of biuret solution into each test tube.

5. Swirl the tubes and note any colour change.

6. Record results in table.

Diagram: