Observing cells through temporary and permanent slides CLASS -IX IGCSE

 

Observing onion peel cells under a compound microscope reveals a structured, brick-like arrangement of plant cells. Key features visible include a thick cell wall, a thin, dense nucleus, and a large, central vacuole that often pushes the cytoplasm to the cell's edge. Staining with substances like safranin or methylene blue.

Cheek cell observation involves scraping the inner mouth lining to study human squamous epithelial cells under a microscope. Cells are stained with methylene blue to reveal a central nucleus, granular cytoplasm, and a thin cell membrane, confirming the absence of a cell wall or large vacuoles, characteristic of eukaryotic animal cells.

observing red blood cells (RBCs) requires a light microscope, typically  to visualize their small  biconcave, disc-like shape, which appears pale pink/red, lacks a nucleus, and shows a "dumbbell" profile. WBC's are little larger with multi nucleated appearance.

Students prepared temporary slides on their own. They used stains to observe the onion and cheek cells and glycerol over the stained sample so that sample does not dry. Then then put coverslip over the stained samples. observed under the microscope. 

The activity was a good learning experience for the learners to make them develop their lab skills, and give them concept clarity. 

Observing Paper Chromatography

Paper chromatography is a simple technique used to separate mixtures (like ink or plant pigments) into their individual components based on their solubility in a solvent and attraction to filter paper. The mixture travels up the paper via capillary action, with faster-moving components separating from slower ones to create a "chromatogram"

Materials Needed:

• Chromatography paper (or filter paper cut into strips)
• Water-soluble markers (black, green, or brown work best)
• Solvent (Water for markers)
• Gas jar
• Pencil
• Tape or a pencil to hang the strip

Procedure:

1. Prepare the Paper: Cut the paper into a strip and use a pencil to draw a straight line about 2 cm from the bottom (baseline).
2. Spot the Sample: Place a small dot of the marker ink in the center of the pencil line. Keep the spot small to prevent smearing.
3. Set Up the Solvent: Pour a small amount of water into the beaker, ensuring the water level is below the pencil line so the ink doesn't dissolve directly into it.
4. Develop the Chromatogram: Suspend the paper in the beaker so the bottom tip touches the water.

Observation:  As water rises up the paper, it carries the dyes at different speeds, separating them. Learners observe different colored dyes ispots in the chromatogram.

Learners enjoyed the activity and understood chromatography.