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Why onion is used in this experiment?

Why onion is used in this experiment?

The epidermal cells of onions provide a protective layer against viruses and fungi that may harm the sensitive tissues. Because of their simple structure and transparency they are often used to introduce students to plant anatomy or to demonstrate plasmolysis.

Why doesn’t an onion have chloroplasts?

The chloroplasts float around in the cell fluid (called cytoplasm) and try to orient themselves so that they are exposed to as much light as possible. Since the onion bulb grows underground, it doesn’t see any sunlight and so it doesn’t have any chloroplasts for photosynthesis.

How do you make an onion cell slide?

Making slides

  1. Peel a thin, transparent layer of epidermal cells from the inside of an onion.
  2. Place cells on a microscope slide.
  3. Add a drop of water or iodine (a chemical stain).
  4. Lower a coverslip onto the onion cells using forceps or a mounted needle. This needs to be done gently to prevent trapping air bubbles.

Is onion bulb a tissue?

The onion bulb consists of several layers of pigmented, papery scales surrounding fleshy storage scales that comprise an upper epidermis, an intermediate parenchyma tissue, and a lower epidermis. Cell-wall material (CWM) was prepared from the component tissues and analyzed for its carbohydrate and phenolic composition.

What type of cell is the onion cell?

eukaryotic cell
Onion cell is a eukaryotic cell with well-defined membranes around the organelles. It also has a well-defined and membrane nucleus.

What would we see if we tried observing the onion peel without putting the iodine solution?

Although onions may not have as much starch as potato and other plants, the stain (iodine) allows for the little starch molecules to be visible under the microscope. The onion peel may get decayed or the onion peel would die.

How do you examine an onion cell?

Peel a thin layer of onion (the epidermis) off the cut onion. STEP 2 – Place the layer of onion epidermis carefully on the glass slide, and cover with a cover slip. STEP 3 – Stain the layer of onion with food colouring. STEP 4 – View your onion cells.

Why can’t you see the vacuole in onion cells?

Onion cells are not green. They get no light, so do not need chloroplasts. appear mainly around the outside of the cell because the central vacuole takes up most of the space and pushes them to the outside. These are blood cells.

Why is iodine added to onion peel?

Given that iodine tends to bind to starch, it stains the starch granules when the two come in to contact making them visible. Although onions may not have as much starch as potato and other plants, the stain (iodine) allows for the little starch molecules to be visible under the microscope.

How do you mount an onion cell?


  1. First add a few drops of water or solution on the microscope slide to avoid dryness and wilting.
  2. Take a small piece of onion and using tweezers, peel off the membrane from the underside (the rough side).
  3. Place the membrane flat on the surface of the slide.
  4. Add a drop of Iodine solution to the onion skin.

What is onion and it characteristics?

It is a biennial plant, but is usually grown as an annual. Modern varieties typically grow to a height of 15 to 45 cm (6 to 18 in). The leaves are yellowish- to bluish green and grow alternately in a flattened, fan-shaped swathe. They are fleshy, hollow, and cylindrical, with one flattened side.