Sheenagh wants to observe the onion cells under the microscope. Which of the following will she do to achieve her goal?
a.Sheenagh will adjust the mirror so the light could go up through the stage and into the specimen
b. Sheenagh will switch the lens from low powered objective to high power objective
c. Sheenagh will adjust the course adjustment so she could see clearly the specimen
d. All of the above
Answers
Explanation:
Onion Cells Under a Microscope
Requirements, Preparation and Observation
The bulb of an onion is formed from modified leaves. While photosynthesis takes place in the leaves of an onion containing chloroplast, the little glucose that is produced from this process is converted in to starch (starch granules) and stored in the bulb.
Chlorophyll and chloroplasts responsible for photosynthesis are therefore only present in the leafy part of the onion (above ground) and absent in the bulb (which grows below ground).
Unlike animal cells (such as cheek cells) the cell wall of an onion and other plants are made up of cellulose, which protects the cell and maintains its shape.
How to Obtain a Thin Layer of Onion Cells
An onion is made up of layers that are separated by a thin membrane. For this experiment, the thin membrane will be used to observe the onion cells. It can easily be obtained by peeling it from any layer of the onion using tweezers.
How to Prepare a Wet Mount Slide
A thin onion membrane,
Microscopic glass slides,
Microscopic cover slips,
A needle,
Blotting paper,
Dropper,
Iodine Solution,
Water,
Microscope
**Note- In microscopy, wet mount refers to a glass slide holding a specimen suspended on a drop of liquid for examination.
Moreover, to avoid breaking the slide and damage to the microscope objective lenses during observation, it's important that the optical tube be lowered to the point that the objective lens is as close to the slide as possible.
This should be done starting with low power while looking from the side of the microscope rather than through the eye piece. From this point, it becomes easier to focus for clarity without any accidents.
Add a drop of water at the center of the microscopic slide
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)