Activity 2.3 Let us investigate, To prepare and observe temporary slides of plant cells. Class 9

Activity 2.3 Let us investigate, To prepare and observe temporary slides of plant cells. Class 9

Activity 2.3 Let us investigate

Aim: To prepare and observe temporary slides of plant cells (onion/Rhoeo leaf) and human cheek cells, compare their structures and study the effect of a concentrated sugar solution on them.

Material Required: Onion or Rhoeo peel, coverslip, safranin, toothpick, cotton, glass slide, methylene blue, microscope.

Procedure:

A. Onion peel

1. Prepare temporary slides of a thin peel of an onion leaf or a Rhoeo (Cradle lily) leaf.
2. Mount it with safranin using cover slip to observe it plant cells under microscope.

B. Human Cheek Cells

1. Prepare a temporary slide of cheek cells by gently scraping the inner side of your cheek with a cotton swab or the blunt end of a toothpick.
2. Spread the cheek cells on a clean glass slide.
3. Add a drop of water followed by a few drops of methylene blue stain and carefully place a coverslip.
4. Observe both the slides under microscope.

Observations: Onion peel cells / Rhoeo leaf peel cells are box-shaped and regularly arranged. Cheek cells are irregularly arranged.

After placing in 20 per cent sugar solution:

1. In plant cells, the cytoplasm shrinks away from the cell wall (plasmolysis) and the cell becomes flaccid.
2. In human cheek cells, the cell shrinks due to water loss (exosmosis) and becomes distorted

Conclusion:

Plant cells and animal cells differ in structure mainly due to the presence of a cell wall in plant cells. Both types of cells lose water when placed in a concentrated sugar solution due to osmosis, but plant cells show plasmolysis because of the rigid cell wall, while animal cells simply shrink and get distorted.