Allium (onion) cells

1. Where are many of the nuclei positioned? Explain why.
   Off center to the side.
   Central vacuole is in the center.
2. Many of the nuclei look as they are centrally located, but they are actually not centrally located. Explain.
   Nucleus can be near top or bottom of a 3-dimensional cell.
3. How is the nucleus positioned in a cell?
   Near the center in most cells; off center in plant cells.

Elodea cells

4. Identify the differences between Elodea cells and onion cells. Provide explanation of the differences.
   Onion cells lack chloroplasts: its bulb is underground and does not undergo photosynthesis.
5. Describe what you see as you focused up and down through the onion and Elodea. Explain the changes that you see as you focus up and down in terms of the overall dimensions of a cell and the position of organelles.
   The cell is 3-dimensional, and focusing up/down allows us to see organelles through 3-dimensional space.

Euglena cells p. 74

6. Which structure is used for locomotion?
   Flagellum.
7. Describe the response that Euglena makes to light. Explain why this behavior is beneficial and how it is accomplished.
   Should move toward light, since it is photosynthetic. Locomotion is through bending of flagellum.
8. Discuss similarities and differences that Euglena has with plant cells.
   Similarities: chloroplasts, nuclei.
   Differences: Flagellum for locomotion, no central vacuole, no cell wall.

The human cheek cell, a type of squamous epithelium. p. 75

6. Do you think all animal cells look like the cheek cells? Why or why not?
   No - they may be different cell types and serve different functions.
7. Provide the function of iodine or methylene blue in the study of cells.
   They help stain organelles.
8. Are cheek cells thick or thin? How can you tell?
   Thin: not much 3-dimensional focusing to see organelles.
9. Where is the nucleus positioned? Is it positioned as in the onion cell? With reference to the last question, explain why or why not based on cell structure.
   Positioned in the center. There is no central vacuole, and the nucleus is the most important organelle in the cell.

Paramecium cells p. 76

13. How does Paramecium respond to light?
    Should be no response.
14. Does Paramecium have a flat or 3-dimensional structure? What from your observations indicates structure?
    3-dimensional; can sometimes see a cell rotating.
15. What structure is used for locomotion and to gather food?
    Cilia.
16. Provide similarities between cells of animals and plants. Identify ways in which cells of animals and plants differ. How does the cellular structure of Paramecium compare to that of animal and plant cells.
    Similarities: nucleus and other organelles, plasma membrane, multicellular.
    Differences: plant cells have chloroplasts, central vacuole, cell wall.
    Paramecium is unicellular, motile.