Looking at cells
ATL
• Organization skills: Use technology effectively and productively
• Critical-thinking skills: Draw reasonable conclusions and generalizations
In this activity you will examine animal and plant cells under the microscope.
You will draw and annotate diagrams of the cells you see. Materials you will need for this activity:
• Microscope
• Slides and cover-slips
• Methylene blue solution (0.5% to 1%)
• Plastic pipette or dropper
• Sterile, individually packed cotton swabs
• Detergent
Safety: Make sure you dispose of the cotton swab in a beaker of detergent to avoid germs being spread. Avoid contact with methylene blue as it is a stain.
1 Take a clean cotton swab and gently scrape the inside of your mouth.
2 Smear the cotton swab on the centre of the microscope slide. Put the cotton wool bud into detergent as soon as you have finished with it.
3 Add a drop of methylene blue solution and place a cover-slip on top. Do not add too much solution! The methylene blue stains the nucleus blue.
4 Remove any excess solution by allowing a paper towel to touch one side of the cover-slip.
5 Place the slide on the microscope, with 4× (low) or 10× (medium power) objective lens in position, and find a cell. Then view at higher magnification.
6 Draw the cell. What structures can you see?
1 Pick an entire healthy looking Elodea leaf, using your fingers or cutting the leaf off with small scissors.
2 Place the leaf on the microscope slide.
3 Add a drop of water and a cover-slip.
4 If you do not have access to Elodea, look at the plant on the following website: www.exploratorium.edu/imaging-station/students/elodea.html#elodea or use the following search terms: Elodea, cells, microscope.
5 Draw and label Elodea cells.
6 Look carefully at the chloroplasts (the green structures in plants that carry out photosynthesis).
Can you see them moving? How do you think they move, and why?
In this activity, we have observed and interpreted microscopic information by using staining techniques and the correct use of the objective (magnification) lenses.
Assessment opportunities
• In this activity you have practised skills that are assessed using Criterion C: Present data in visual forms; Interpret data and explain results using scientific reasoning.