The Microscope in Cell Studies

Structural Features of Eukaryotic Cells (I)

Structural Features of Eukaryotic Cells (II)

Structural Features of Eukaryotic Cells (III)

Comparison of Structural Features of Prokaryotic and Eukaryotic Cells

Cell Structure

Lipids

Proteins (I)

Water

Biological Molecules

Mode of Action of Enzymes

Factors that Affect Enzyme Action

Enzymes

Fluid Mosaic Model of the Cell Surface Membrane

Structural Components of the Cell Surface Membrane and their Functions

Diffusion, Facilitated Diffusion and Osmosis

Cell Membranes and Transport

Mitotic Cell Cycle

The Mitotic Cell Cycle

Structure of Transport Tissues and their Functions

Water Movement in Plants

Translocation

Transport in Plants

The Mammalian Circulatory System

The Heart

Transport in Mammals

The Gas Exchange System

Gas Exchange

Infectious Diseases

Antibiotics

Antibodies

Vaccination

Immunity

Photosynthesis

Principle of Homeostasis and Deamination

Structure of the Human Kidney and its Function (I)

Homeostasis

Variation

Selection and Evolution

<ul><li>Microscopy is the technique used to examine microscopic objects in a laboratory using a microscope.</li><li>There are two types of microscope: light microscope and electron microscope<ul><li>Light microscope uses light to illuminate a specimen and has glass lenses to magnify the specimen’s image.</li><li>An electron microscope uses a beam of electrons to illuminate a specimen and has electromagnetic lenses to magnify the specimen’s image.</li></ul></li><li>Parts of light microscope: <img loading="lazy" width="679" height="556" class="wp-image-6904" style="width: 600px;" src="https://assets.mysecondteacher.com/ap-websites/wp-content/uploads/2025/08/image-4.png" alt="parts-of-light-microscope" srcset="https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-4.png 679w, https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-4-300x246.png 300w" sizes="(max-width: 679px) 100vw, 679px" /><ul><li>A photomicrograph is an image taken through a light microscope and an electron micrograph is an image taken through an electron microscope. <img loading="lazy" width="803" height="381" class="wp-image-6906" style="width: 500px;" src="https://assets.mysecondteacher.com/ap-websites/wp-content/uploads/2025/08/image-5.png" alt="photomicrograph" srcset="https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-5.png 803w, https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-5-300x142.png 300w, https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-5-768x364.png 768w" sizes="(max-width: 803px) 100vw, 803px" /></li><li>In microscopy, very small units of measurements are used, such as millimetres (mm), micrometres (µm) and nanometres (nm).</li></ul></li><li>Working mechanism of a light microscope <img loading="lazy" width="718" height="671" class="wp-image-6909" style="width: 500px;" src="https://assets.mysecondteacher.com/ap-websites/wp-content/uploads/2025/08/image-6.png" alt="" srcset="https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-6.png 718w, https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-6-300x280.png 300w" sizes="(max-width: 718px) 100vw, 718px" /></li></ul>



<ul><li>Working mechanism of an electron microscope <img loading="lazy" width="696" height="904" class="wp-image-6911" style="width: 500px;" src="https://assets.mysecondteacher.com/ap-websites/wp-content/uploads/2025/08/image-7.png" alt="working mechanism of an electron microscope" srcset="https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-7.png 696w, https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-7-231x300.png 231w" sizes="(max-width: 696px) 100vw, 696px" /></li></ul>



<ul><li>Difference between magnification and resolution:<ul><li>Magnification: It is the ratio of the size of the image to that of the specimen. It can be calculated by using the formula: $$\text{Magnification (M)} = \frac{\text{Observed size of the image (I)}}{\text{Actual size (A)}}$$ </li></ul><ul><li>Resolution: It is the ability of a microscope to visually distinguish between two adjacent points that are very close. Greater the resolution, greater the detail/clarity that can be seen in an image. <img loading="lazy" width="602" height="216" class="wp-image-6913" style="width: 500px;" src="https://assets.mysecondteacher.com/ap-websites/wp-content/uploads/2025/08/image-8.png" alt="Resolution" srcset="https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-8.png 602w, https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-8-300x108.png 300w" sizes="(max-width: 602px) 100vw, 602px" /></li></ul></li></ul>



<ul><li>Calculation of actual size of a specimen: $$\text{Actual size (A)} = \frac{\text{Observed size of the image (I)}}{\text{Magnification (M)}}$$</li></ul>



<ul><li>Comparison between magnification and resolution<ul><li>A microscope with a high magnification power does not necessarily produce a clearer image. In order to produce a clearer image, a microscope must also have a good resolution.</li><li>For example, an electron microscope has a higher resolution (0.5 &#8211; 0.1nm) than that of a light microscope (200 nm) and therefore it produces a much clearer image of the same object as shown below. <img loading="lazy" width="670" height="368" class="wp-image-6915" style="width: 500px;" src="https://assets.mysecondteacher.com/ap-websites/wp-content/uploads/2025/08/image-9.png" alt="light-microscope" srcset="https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-9.png 670w, https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-9-300x165.png 300w" sizes="(max-width: 670px) 100vw, 670px" /></li></ul></li></ul>



<ul><li>Measurement of size of a specimen using a light microscope:<ul><li>It involves use of an eyepiece graticule and stage micrometer scale: </li><li>Step 1: Eyepiece graticule is placed in the eyepiece lens of the microscope. Generally, it has 100 divisions on its scale.</li><li>Step 2: Stage micrometer placed under objective lens. Generally, it has a scale value of 0.1 mm for every 10 divisions. <img loading="lazy" width="884" height="319" class="wp-image-6930" style="width: 500px;" src="https://assets.mysecondteacher.com/ap-websites/wp-content/uploads/2025/08/image-16.png" alt="stage micrometer" srcset="https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-16.png 884w, https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-16-300x108.png 300w, https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-16-768x277.png 768w" sizes="(max-width: 884px) 100vw, 884px" /></li></ul><ul><li>Step 3: The eyepiece graticule calibration is done by counting the number of graticule units that perfectly superimpose with the scale of stage micrometer as shown below. <img loading="lazy" width="640" height="438" class="wp-image-6932" style="width: 500px;" src="https://assets.mysecondteacher.com/ap-websites/wp-content/uploads/2025/08/image-17.png" alt="Eyepiece-graticule-scale" srcset="https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-17.png 640w, https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-17-300x205.png 300w" sizes="(max-width: 640px) 100vw, 640px" /></li><li>Step 4: Then the value of each graticule unit is determined by the unitary method of calculation.</li><li>Step 5: Based on the number of graticule units that the specimen occupies (as shown in the image below), the size of the specimen is determined by multiplying the number of units by the value of each unit. <img loading="lazy" width="745" height="347" class="wp-image-6992" style="width: 500px;" src="https://assets.mysecondteacher.com/ap-websites/wp-content/uploads/2025/08/image-42.png" alt="Eyepiece-graticule-in-the-eyepiece-of-the-microscope" srcset="https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-42.png 745w, https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-42-300x140.png 300w" sizes="(max-width: 745px) 100vw, 745px" /></li><li>Step 6: Size of the specimen is expressed in appropriate units like millimetre (mm), micrometre (μm) and nanometre (nm).</li></ul></li><li>During the measurement of the scale bar in an image to find the actual size of the image, parallax error is likely to occur.<ul><li>This error occurs while taking a measurement using a ruler or a measuring cylinder. <img loading="lazy" width="538" height="223" class="wp-image-6999" style="width: 350px;" src="https://assets.mysecondteacher.com/ap-websites/wp-content/uploads/2025/08/image-45.png" alt="measurement-of-the-scale-bar" srcset="https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-45.png 538w, https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-45-300x124.png 300w" sizes="(max-width: 538px) 100vw, 538px" /></li></ul></li></ul>



<ul><li>Preparation of temporary slide to observe under a microscope:<ul><li>Step 1 :&nbsp; Thin section of a cellular specimen should be placed on a clean and dry glass slide and one or two drops of stain should be added. <img loading="lazy" width="226" height="167" class="wp-image-7003" style="width: 150px;" src="https://assets.mysecondteacher.com/ap-websites/wp-content/uploads/2025/08/image-47.png" alt="preparation-of-temporary-slide"></li><li>Step 2: A drop of glycerine should be mixed with the stain. This prevents the specimen from drying out. <img loading="lazy" width="229" height="172" class="wp-image-7007" style="width: 150px;" src="https://assets.mysecondteacher.com/ap-websites/wp-content/uploads/2025/08/image-49.png" alt="preparation-of-temporary-slide"> <img loading="lazy" width="268" height="171" class="wp-image-7011" style="width: 150px;" src="https://assets.mysecondteacher.com/ap-websites/wp-content/uploads/2025/08/image-51.png" alt="preparation-of-temporary-slide"></li></ul><ul><li>Step 3: A coverslip should be carefully lowered over the specimen to protect the microscope lens. This also prevents the specimen from drying out. <img loading="lazy" width="268" height="166" class="wp-image-7015" style="width: 250px;" src="https://assets.mysecondteacher.com/ap-websites/wp-content/uploads/2025/08/image-53.png" alt="preparation-of-temporary-slide"></li><li>Step 4: The slide should be kept on the stage of the microscope and observed first under a low power objective lens and then under a high power objective lens. <img loading="lazy" width="288" height="273" class="wp-image-7017" style="width: 250px;" src="https://assets.mysecondteacher.com/ap-websites/wp-content/uploads/2025/08/image-54.png" alt="preparation-of-temporary-slide"></li></ul></li></ul>



<ul><li>Tips to draw cells from micrographs and microscope slides:<ul><li>S &#8211; Shape and size</li><li>O &#8211; Outline</li><li>L &#8211; Labels</li><li>D &#8211; Details <img loading="lazy" width="768" height="354" class="wp-image-7019" style="width: 600px;" src="https://assets.mysecondteacher.com/ap-websites/wp-content/uploads/2025/08/image-55.png" alt="photomicrograph-of-stained-onion-cells" srcset="https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-55.png 768w, https://cms.mysecondteacher.com/wp-content/uploads/2025/08/image-55-300x138.png 300w" sizes="(max-width: 768px) 100vw, 768px" /></li></ul></li></ul>

1.01 - The Microscope in Cell Studies

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