Onion Cell Lab - Y9

The Onion Cell: Lab Assignment

Name: _____________________ Date: / /

The Onion Cell: Lab

Aim (What is it that you want to find out?)

Materials (What exactly do you need to do this experiment?)

Whole white onion

Microscopes

Microscope slides IodineDropper

Cover slips

Method/Procedure (A list of all the steps that you take to do this experiment)

Preparing the wet mount slide of onion skin

1. Break an onion slice in two. 2. Carefully pull the slice apart.

3. Use tweezers to pull off a very thin piece of onion skin (the thinner, the better)

4. Place the skin in the center of the slide. Try to keep it from folding; get it as flat as possible.

5. Add a drop of water to the onion skin and cover with a cover slip.

6. Press the cover slip down carefully to remove any air bubbles.

7. Place the slide on the stage of the microscope, set it to low power, adjust the focus so the onion slice is clear. Draw four or five cells as seen. Label the cell walls.

8. Switch to higher power and try to identify the cell membrane, nucleus, and cytoplasm.

Staining the onion cells

1. Lift up the cover slip and add one or two drops of iodine to the slide.2. Lower the cover slip and examine the cells on higher power.

3. Iodine stains different parts of the cells so that different organelles can be seen. Draw and label the cell wall, cell membrane, cytoplasm, and nucleus.

Observations (What do you see?)

Onion Cell Drawings

Conclusions & Discussion

1. What is the general shape of the onion cells?

2. Describe what you saw without the stain.

3. Why is it easier to see the onion cells after they are stained?

4. All plant cells have cell walls. What is the function of the cell wall?

5. Count the number of cells that are seen in the field of view under low power magnification and also under higher magnification. Compare the number of cells observed in each field of view. What difference do you see?

6. What is the job of the nucleus? Were you able to see the cell nuclei?

7. What would you do differently if you were to do this experiment again? What mistakes will you make?

Scientist: _____________________

Class: _______________________

1) Overall

Report includes name & date Report is neat Report was handed in on time

2) Aim Is complete

Observations

Diagrams neatly completed Diagrams in pencil

Diagrams are accurately labelled

Observations are clear and detailed

Conclusion Question 1 is correct

Question 2 is correct



Question 5 is correct Question 6 is correct


___

15Scientist: _____________________

Class: _______________________

3) Overall

Title page includes name & date Report is neat

Report was handed in on time

4) Aim Is complete

Observations

Diagrams neatly completed

Diagrams in pencil

Diagrams are accurately labelled

Observations are clear and detailed

Conclusion Question 1 is correct







___

15

Name: ___________

Remember:

Use pencil only

No sketchy lines

No shading

Include magnification

Documents

Onion Cell Lab - Y9