Activity 2.1 Let us estimate the size of a cell, To estimate the real size of an onion peel cell. Class 9

Activity 2.1 Let us estimate the size of a cell, To estimate the real size of an onion peel cell. Class 9

Activity 2.1 Let us estimate the size of a cell

Aim: To estimate the real size of an onion peel cell.

Material Required: A transparent ruler, microscope.

Procedure:

1. Take a ruler with mili metre (mm) markings, and place it on the stage of microcsope, focus on it using the adjustment knob and observe the diameter.
2. Convert the diameter from mm to micrometre (pm). Suppose the diameter of the visible field is 5mm, meaning 5 × 1000 = 5000 pm.
3. Remove the ruler and place an onion peel slide on the stage of the microscope.
4. Focus on the slide and count the number of cells present along the diameter of the field. Estimate the real size of the cell.

Observation/Calculation:

Cell are seen along the diameter = 25

Unit Conversion 1 millimeter (mm) = 1000 micrometer (μm)

The diameter of visible field = 5mm then, 5 × 1000 = 5000 μm

Estimate size of the onion peel cell = [latex]\frac{Diameter of the visible field in micrometre}{Number of cells along the diameter}[/latex]

= [latex]\frac{5000 \mu \mathrm{~m}}{25}[/latex] = 200 μm

Result: The estimated size of an onion peel cell is 200 μm

Conclusion:

A microscope allows us to see very small structures clearly and is an essential tool for studying cell structure. The total magnification of a microscope depends on the magnifying power of the eyepiece and the objective lens. If both have magnifying power of 10X, the total magnification is 100X - meaning a cell of estimated size 200 pm will appear 100 times larger.