The purpose of the lab is to explore the smallest part of a plant, the plant cell. It will be necessary to come into the classroom to complete the lab since a microscope will be used. A copy of the lab can be seen below. Please see me to schedule a time during which you can be in room C-8 to work on this lab. Plan on spending about 45 minutes to complete lab 1.

To complete this lab you will need to spend about 45 minutes in room C-8. All equipment and supplies are in the back of the room. Use the reference material to review cell structures and functions if its been awhile since you studied biology. Be sure to clean up everything before you leave. The best times to accomplish this assignment are: Periods 5 or 8. Before or after school or during lunch.

Follow the procedure below. Provide drawings or answers at each number. Put the drawings and answers to the questions in your folder when complete.

Part A. Onion Cells

Take a one layer of a section of cut onion and hold it so the concave surface is towards you. Tear off the transparent, paper thin layer called the epidermis with forceps. It's a bit like peeling skin after a bad sunburn and should peel easily. Take a piece of the epidermis and prepare a wet mount slide as follows:

• put a small piece of the epidermis on a clean microscope slide (keep it flat, don't let it fold)
• put a drop of water and then a cover slip on the onion

View the onion skin with a microscope using low power.

1. Sketch a small section of the field of view to show the shapes and arrangements of the cells.

Remove the coverslip and place a tiny drop of dye onto the onion. Warning! The dye will stain clothes and skin! Replace the cover slip. Focus under low power switch to high power. Remember to use only the small focus knob when under high power!

2. Sketch a single cell. Include as much detail as you can. Label the cell wall, cell membrane, cytoplasm, and the nucleus.

Using forceps remove a young leaf from the tip of an elodea plant. Place it upside down on a clean slide. Add a drop of water and a coverslip. Observe the leaf under low power. By slowly turning the fine focus knob (small one) back and forth, count and record the number of cell layers in the leaf.

3. Cell layers ____

Switch to high power. Select an "average" cell and focus on it.

4. Is there any evidence that the cell is living? If so, what is the evidence?

5. Sketch the leaf cell, including as much detail as you can see. Label any parts you can identify.

Place a drop of salt solution at one edge of the coverslip. Observe the cells closest to the salt for changes.

6. What has happened to them? Sketch what you see.

7. What is the main difference between the onion and elodea cells? How do you explain the difference?