BIOLOGY LAB
Animal and
Plant Cells


When a specimen must be prepared for observation, the object should always be viewed as a wet mount.  A wet mount is prepared by placing a drop of liquid on a slide or, if the material is dry, by placint it directly on the slide and adding a drop of water or stain.  The mount is then covered with a coverslip.  The instructor will demonstrate how to make a wet mount.

Exercise 1:

HUMAN EPITHELIAL CELLS
Epithelial cells cover the body's surface and line its cavities.
  1. Obtain toothpick.
  2. Gently scrape the inside of yourcheek with the toothpick.
  3. Place the scrapings on a clean, dry slide.
  4. Add a drop of iodine stain and cover with a coverslip.
  5. Observe under the microscope, using the directions for focusing given above.  Start with the scanning power objective to find some cells, then observe under both low and high power.
  6. Locate the cell membrane, the cytoplasm, and the nucleus.
  7. Make a drawing of what you see.  Be sure to label the drawing with what it is, and what power you were using when you made your drawing.

    8. Exercise 2:

PLANT CELLS
  1. With your fingers, strip a thin, transparent layer of cells from a piece of onion.
  2. Place it gently on a clean, dry slide.
  3. Add a drop of iodine stain and cover with a coverslip.
  4. Observe under the microscope and draw what you see.  Be sure to label your drawing.
  5. Locate the cell wall.  Is a nucleus visible?
  6. Count and record the number of cells across the diameter of the high power field, both lengthwise and side to side.
  7. Using the number you calculated in exercise 3, calculate and record the length and width of an onion cell in micrometers.
  8. Draw what you see.  Be sure to label your drawing.

    Exercise 3:

PLANT CELLS - More samples.

  1. Follow the same procedure above and look at other types of plant cells.
  2. Use banana and potato.
  3. Draw what you see.  Be sure to label your drawing.

Conclusion Questions:

  1. Explain how you were able to observe animal and plant cells
  2. Why did you stain the cells?
  3. Record some obvious differences between the human cheek cells and the onion cells.
  4. Record any similarities between the two types of cells.
  5. Record some differences and similarities between the different plant cells you observed.
  6. What new structures were you able to identify on the potato and banana cells?