Temporary Mount: Human Cheek Cells MCQs Quiz | Class 9

This quiz covers Class IX Science (Code 086) Practicals (Unit II) specifically focusing on the preparation of a temporary mount of human cheek cells. It tests your understanding of staining techniques using Methylene blue, slide preparation steps to avoid air bubbles, and identification of cell components like the nucleus and cell membrane in a labeled diagram. Submit your answers to view your score and download the PDF solution.

Overview: Human Cheek Cells Experiment

In this Class 9 practical (Unit II), students learn to prepare a temporary mount of animal cells using human cheek cells. Unlike plant cells (like onion peel), animal cells lack a cell wall. The experiment focuses on observing the basic structure of an animal cell under a compound microscope.

Key Components Observed

  • Cell Membrane: The thin outer boundary of the cell.
  • Cytoplasm: The jelly-like substance filling the cell.
  • Nucleus: A dense, spherical structure usually located near the center of the cell.

Materials and Procedure

To view the transparent cells, a specific stain is required.

Component Material Used Purpose
Stain Methylene Blue To color the nucleus and cytoplasm for visibility.
Mounting Medium Glycerin To prevent the specimen from drying out.
Tool Clean Toothpick To gently scrape the inner lining of the cheek.

Important Precautions

  • Scraping: Scrape gently to avoid injuring the cheek lining.
  • Spreading: The material should be spread evenly on the slide to prevent cell clumping.
  • Air Bubbles: The coverslip must be lowered gently using a needle to avoid trapping air bubbles, which obstruct the view.
  • Excess Stain: Use blotting paper to remove extra stain from the edges of the coverslip.

Quick Revision List

  1. Cheek cells are epithelial cells (Squamous epithelium).
  2. They are irregular in shape with no rigid cell wall.
  3. The nucleus is central, unlike plant cells where the vacuole pushes it to the side.
  4. Methylene blue stains the nucleus deeply blue.

Extra Practice Questions

1. Why is water used before adding stain?
To wash the cells and ensure they remain hydrated before staining.

2. What is the magnifying power usually used?
Initially 10X (Low Power) to locate cells, then 40X (High Power) to see details.

3. How do cheek cells differ from onion cells?
Cheek cells have no cell wall and a central nucleus; onion cells have a cell wall and a large vacuole.

4. Why discard the first scraping?
It may contain food particles; subsequent scrapings give cleaner cells.

5. What happens if the slide dries out?
The cells shrink and become distorted, making observation impossible.