Life Cycle - Organisms (5A)
Lab 

   
OBJECTIVES:
  • Discovering the differences between plant and animal cells.
  • Exploring the different organelles of a cell.
VOCABULARY:
  • cell wall
  • chlorophyll
  • chloroplast
  • starch grain
  • vacuole
MATERIALS:

Students use a microscope to observe plant and animal cells.

BACKGROUND:

Cells are the fundamental units of living material. The bodies of all living things are formed from cells, and without cells there would be no life. Every large living thing is made of billions of cells that have different sizes, shapes, and functions. Cells contain special structures called organelles which have specific functions for maintaining the health of cells. The types of jobs that organelles perform include taking in food and breaking it apart into simple molecules, releasing energy from food, building and repairing cell parts, getting rid of harmful wastes, and making more cells.

These organelles can help identify whether a cell comes from a plant or an animal. Only plants, for instance, have chloroplasts and starch grains. Chloroplasts are needed for photosynthesis and starch grains (amyloplasts) store the starch that is produced by photosynthesis. Vacuoles in an animal cell are not as large as those in plant cells. Learning the specific functions of the various organelles will continue in the post lab, so it is important that the students recognize and be able to distinguish the differences between animal and plant cells.

PROCEDURE:
  1. Students have compared an ideal model of a plant cell with an ideal model of an animal cell. However, when you look at real samples, the differences may not be as obvious as they were on the models.
      
  2. Have the students look at a thin slice of onion and animal cell as directed in the lab. Cut the onion skin very thin and put a drop of food coloring and then blot it. Use some hamburger meat and squish the cells on a glass slide. Make sure the students see that the onion cell has a thicker wall around each of the cells. This is the only real difference the students can see with the Swift-GH. You may want to use a higher magnification.
      
  3. Then have the students look at the 3 unknowns (pine stem x.s. [plant], hyaline cartilage tracheo region s.x. [animal], and bone cancellous sec. [animal]. The major difference is the cell wall that can be seen in the pine stem.

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