Shyam being very inquisitive, didn’t listen to the teacher’s instruction properly. He took the thin layer of onion peel with a drop of water on the glass slide. He placed the coverslip on it and start observing the slide under a microscope. But he was unable to see the cells of onion peel properly.
a. What do you think he might have forgotten?
b. What is the function of a dye?
c. What are the main functional regions of a cell? Explain
Answers
a. PROCEDURE:
1. Add a drop of water at the center of the microscopic slide
2. Having pulled of a thin membrane from the onion layer, lay it at the center of the microscopic slide (the drop of water will help flatten the membrane)
3. Add a drop of iodine solution on the onion membrane (or methylene blue)
4. Gently lay a microscopic cover slip on the membrane and press it down gently using a needle to remove air bubbles.
5. Touch a blotting paper on one side of the slide to drain excess iodine/water solution,
6. Place the slide on the microscope stage under low power to observe.
7. Adjust focus for clarity to observe.
b.
Safranin is used to color type onion peel during experiments. This is done to assure the visibility of different organelles . This dye is used in histology and cytology. As the onion peel is transparent in color it needs to be colored to see the organelles in microscope .
c.
Cells provide six main functions. They provide structure and support, facilitate growth through mitosis, allow passive and active transport, produce energy, create metabolic reactions and aid in reproduction.
Onion peel cells are the cells of epithelium tissue. They protect the internal cells of the onion bulb.