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Lesson 3 Microscopy

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Course: Science 10 [5 cr] - AB Ed copy 1
Book: Lesson 3 Microscopy
Printed by: Guest user
Date: Sunday, 7 September 2025, 6:45 PM

Table of contents

  Introduction


 

Microscopes have played an important role in the study of biology.

A3.1 Magnification of bacteria on a human hand
Many parts of the living and non-living world are not able to be seen with the naked eye. Scientists had to invent a way to see objects that were too small to see otherwise. This invention opened a whole new world for us to study. Who knew there were so many organisms living in and around us that we didn’t even know about? By the end of this lesson, you will know how microscopes were invented and how they are used today.

  Target

By the end of this unit, you will be able to
  • describe how scientists have increased their knowledge of cell structure and function because of developments in microscope technology and staining techniques

  Watch This


Looking at Cells 

https://adlc.wistia.com/medias/r3q8iprqnk


This video talks about the importance of microscopes and shows some examples of what can be seen.
 

  Invention of the Microscope


Microscopes have been around in one form or another for hundreds of years.
The first microscope was believed to have been invented by Hans and Zacharias Janssen in 1595. This first microscope was not very strong, but it opened the door for other scientists to start creating their own stronger microscopes. As you read in the previous lesson, both Robert Hooke and Antoni van Leeuwenhoek built their own handmade microscopes to discover the cell. This occurred just 70 years after the Janssens’ invention.


© Wikimedia Commons
A3.3 Hooke’s three-lens microscope
These early microscopes were a type of light microscope called a compound light microscope. A light microscope uses light through lenses to magnify the object. A compound light microscope uses a set of two or more lenses to produce a larger image. The images seen by these microscopes were not very clear and lacked detail. However, it was this type of microscope that was used to discover the cell itself, as well as the different structures found within the cell. As scientists were able to produce higher quality lenses, they were able to create an image that was both more clear and detailed.


© Wikimedia Commons
A3.2 Schematic of Janssen’s microscope

  Read This

Please reread pages 243 to 244 in your Science 10 textbook. Make sure you take notes on your readings to study from later. This time, you should focus on the microscopes the scientists used and how they differed. Remember, if you have any questions or you do not understand something, ask your teacher!

  Practice Questions

Complete the following practice questions to check your understanding of the concept you just learned. Make sure you write complete answers to the practice questions in your notes. After you have checked your answers, make corrections to your responses (where necessary) to study from.

  1. What were the main differences between the microscopes that Hooke and van Leeuwenhoek used? Which one worked better?

    Both scientists used handmade microscopes; however, Hooke’s microscope used three lenses. The light was concentrated on the object being studied by using a glass flask filled with water. Van Leeuwenhoek’s microscope was a simple microscope, meaning it used only one lens. It was small looked similar to a magnifying glass. It did not include a light source. Van Leeuwenhoek’s microscope worked better, as he was able to make higher quality lenses that did not blur the image. The lenses in Hooke’s microscope were of poor quality, so when you tried to see through more than one, all the imperfections added up, making a very blurry image.

  Using a Compound Light Microscope

A compound light microscope is the type of microscope that is commonly found in the classroom.
At one point in your high school career, you will probably use a compound light microscope. Because of this, it is important for you to know how to use one and its general parts. Hover over the i next to the words to see a description of its function.



If you have trouble seeing this interactive, click here.

  Interactive Activity

Micro Basics 

Print students can access the Microscope and Microscope Basics in the Online Resources for Print Students section of their online course.
This activity will take you through the care of, the parts of and how to use a microscope. You can do the activity in parts or all at once, but please make sure you complete the entire activity!

Take a look at pages 478 and 479 in your Science 10 textbook for more information and examples.

  Total Magnification and Unit Conversions


You will notice each objective lens is labelled on your microscope.
The lenses are commonly labelled 10x, 40x, and 100x, but each microscope is different. These labels tell you by how much the objective lens is magnifying the object. The ocular lens is also magnifying the object by 10x. This means you must multiply the objective lens magnification by the ocular lens magnification to get the true magnification of the object. For example, if you are looking through the 10x objective lens, you must multiple 10x by the 10x magnification of the ocular lens: 10 x 10 = 100x. The true magnification of the object is 100x!

Magnification also deals with a fair amount of unit conversion. You have learned about converting from one unit to another in your previous math courses, but here is a short review.

A3.5 Objective lenses labeled 50x and 20x

Example:


A specimen on a slide is 0.02 millimetres ( «math xmlns=¨http://www.w3.org/1998/Math/MathML¨» «mi»mm«/mi» «/math») long. How long is the specimen in micrometres ( «math xmlns=¨http://www.w3.org/1998/Math/MathML¨» «mi»§#956;m«/mi» «/math»)?

 


Step 1: How many μm are in 1 space mm?

Use the conversion chart in your data booklet to look up how many µm are in one mm. There are 1 space 000 space μmin 1 space mm.

Step 2: Cross multiply and divide to solve for «math xmlns=¨http://www.w3.org/1998/Math/MathML¨» «mi»X«/mi» «/math».


«math xmlns=¨http://www.w3.org/1998/Math/MathML¨» «mn»0«/mn» «mo».«/mo» «mn»02«/mn» «mo»§#215;«/mo» «mn»1«/mn» «mo»§#160;«/mo» «mn»000«/mn» «mo»=«/mo» «mn»20«/mn» «/math»
Step 3: Then divide by what is left over.
«math xmlns=¨http://www.w3.org/1998/Math/MathML¨» «mfrac» «mrow» «mi»X«/mi» «mo»§#160;«/mo» «mi»§#956;m«/mi» «/mrow» «mrow» «mn»0«/mn» «mo».«/mo» «mn»02«/mn» «mo»§#160;«/mo» «mi»mm«/mi» «/mrow» «/mfrac» «mo»=«/mo» «mfrac» «mrow» «mn»1000«/mn» «mo»§#160;«/mo» «mi»§#956;m«/mi» «/mrow» «menclose notation=¨circle¨ mathcolor=¨#EB6D2E¨» «mn mathcolor=¨#191919¨»1«/mn» «mo mathcolor=¨#191919¨»§#160;«/mo» «mi mathcolor=¨#191919¨»mm«/mi» «/menclose» «/mfrac» «/math»
 
«math xmlns=¨http://www.w3.org/1998/Math/MathML¨» «mn»20«/mn» «mo»§#247;«/mo» «mn»1«/mn» «mo»=«/mo» «mn»20«/mn» «mo»§#160;«/mo» «mi»§#956;m«/mi» «/math»

«math xmlns=¨http://www.w3.org/1998/Math/MathML¨» «mn»0«/mn» «mo».«/mo» «mn»02«/mn» «mo»§#160;«/mo» «mi»mm«/mi» «/math» is equal to «math xmlns=¨http://www.w3.org/1998/Math/MathML¨» «mn»20«/mn» «mo»§#160;«/mo» «mi»§#956;m«/mi» «/math».

  Watch This

Unit Conversions


These videos will take you through the steps on how to perform basic unit conversions. This may be review for you, or this may be new information. These videos move fairly fast and use units you may not see in Science 10. This is OK, as a conversion works the same for any unit! If you have any questions, please ask your teacher for help.





  Virtual Lab

Microscope Lab - Introduction to the Virtual Microscope


Background Information:

In this unit, you will be using this virtual microscope to observe a grasshopper jaw. This lab will help you become familiar with the virtual microscope and how to use it.

 This microscope has an ocular lens magnification of 10x.

  1. Click on the play icon to open the virtual lab. Print students can access the Virtual Microscope in the Online Resources for Print Students section of their online course.
  2. Click on Exercise 1 under Lab 1.
  3. Click on the procedure tab on the right side of the screen to open the procedure.
  4. Follow the directions found in the procedure. 
  5. Please return to the top of this page and click on analysis to complete the analysis questions.

  1. Why do you think you should always use the course adjustment knob before the fine adjustment knob?

    The course adjustment knob makes large adjustments to the location of the stage and the focus of the specimen. Once you are generally in focus, you can use the fine adjustment knob to make any final adjustments needed.
  2. Using the ruler button on the view screen, estimate the size of the grasshopper jaw using the 4x objective lens.

    The grasshopper jaw is approximately 3.5 mm wide and approximately 3.5 mm tall.
  1. Under which magnification can you use both the coarse adjustment and the fine adjustment knob?

    The coarse adjustment know should only be used on the lowest magnification.  You should only use the fine adjustment knob with the medium and high-powered objective lens to avoid damaging the lens.

  Modern Microscopes

Today, there are many different types of microscopes.


Let’s explore the advantages and disadvantages of the different microscope types and techniques


© Giudicelli F, Özbudak EM, Wright GJ, Lewis J, via Wikimedia Commons
A3.7 Zebra Fish embryo in darkfield illumination.
Scientists use different types of light to increase the clarity of the image they are looking at. Different types of light will sharpen different parts of the cell, so depending on the cell that you are looking at, you may want to use a different kind of light. There are four kinds of illumination that scientists currently use: brightfield, phase contrast, darkfield, and differential interference contrast. Each of these types of illumination shows a different part of a cell. Brightfield illumination is the default kind of illumination when using a compound light microscope. Make sure you look at page 256 in your textbook for examples of each of these kinds of illumination.


A3.8 Skin cells stained using fluorescent dye
This is not a type of microscope but a way of attaching a fluorescent molecule to a structure or cell so it can be easily identified under a microscope. Under ultraviolet light, the fluorescent molecule will glow, allowing the observer to easily pinpoint its location. This technique is used when staining the structure or cell does not show the detail that is needed.

The use of green fluorescent protein (GFP) is a continuation of this. This type of protein comes from a specific type of jellyfish and will glow green under ultraviolet light. Scientists attach this protein to the parts of the cell they wish to study, and it acts like a tiny lamp, lighting up that specific part. A huge advantage to this technique is it does not kill the cell, unlike other staining techniques. This means scientists can study the live cell and how it works.

A3.9 Aequorea victoria jellyfish that produces GFP

A3.10 Confocal microscope
This type of microscope uses a laser to concentrate light onto the specimen. The laser scans each layer of the specimen so the scientist sees an image of a very thin section. If multiple images are taken, a computer can take these images and build a 3-D image. This type of microscope is great for specimens that are too large for a compound microscope. It also allows us to see the detail of a 3-D image.


A3.11 Transmission Electron Microscope
This type of microscope uses a beam of electrons instead of a light wave. This allows the microscope to produce an image with lots of fine details. The electrons either bounce off of or are absorbed into the specimen, leaving an image where no electrons are present.

A TEM produces a 2-D image of a very thin slice of the specimen; it is very difficult to produce a 3-D image using this microscope. It can produce detail close to 100 times greater than the traditional compound microscope. It can also magnify up to 1 000 000x.


A3.12 SEM microscope
A SEM works in a similar way to the TEM except it provides detail about the surface of a specimen, rather than a thin slice of it. A beam of electrons is scanned over the specimen, and the microscope picks up the electrons being reflected off the surface to create a 3-D image. A SEM can magnify up to 300 000x and can be used on live specimens. 

A3.13 Red blood cell on cotton strand

  Digging Deeper


A3.14 Clear vs. blurry image

You may know the words “resolution” and “contrast.” They play a big part in image and video quality. But did you also know they play a big part in microscopes too? Just like an image, the higher the resolution and the better the contrast, the more detail we can see. Scientists have played around with light sources and staining techniques for hundreds of years, trying to get a clearer picture of what they are looking at. Read pages 253 to 256 in your textbook for more information.

Did You Know?


A3.15 Coming Soon

Scientists have continued to develop new microscopes. Recently, a new microscope called a triple-view microscope was developed. This microscope increases the resolution without increasing the amount of light used, providing a clearer, more detailed 3-D image. This allows scientists to study even smaller structures and functions, such as what a virus does once it is inside of a cell. https://quick.adlc.ca/learn-more

Learn More





  Read This

Please read pages 256 to 260 in your Science 10 textbook. Make sure you take notes on your readings to study from later. You should focus on the types of microscopes, how they work, and their advantages and disadvantages. Remember, if you have any questions or you do not understand something, ask your teacher!

  Practice Questions

Complete the following practice questions to check your understanding of the concept you just learned. Make sure you write complete answers to the practice questions in your notes. After you have checked your answers, make corrections to your responses (where necessary) to study from.

  1. Fill in the following chart with information about each type of microscope. The column for the compound light microscope has been filled in for you as an example.

    2.  
    		Compound CLSM TEM SEM
    Image Source
    		light
    Magnification 250x N/A
    Advantage simple to use
    Disadvantage not much detail


     
    		Compound CLSM TEM SEM
    Image Source
    		light laser electron beam
    		electron beam
    Magnification 1500x not mentioned in readings—approx. 2000x 1 000 000x 300 000x
    Advantage simple to use
    		–great for specimens too thick for other microscopes
    –creates 3-D image
    		–very detailed
    –largest magnification
    		–provides detail of surface of specimen
    –can be used on live specimens creates 3-D image
    Disadvantage not much detail
    		–uses extremely small sections of specimen –produces 2-D image
    –uses extremely small sections of specimen
    		–do not see the inside of the cell, only the surface
    –not as high of a magnification as the TEM
  2. How does GFP work? Please explain in your own words.

    3. Always be sure the answers you write are your own, are not copied, and make sense to you. Your answer should be a variation of the following: To use GFP, scientists take a protein from a special jellyfish and attach it to the structure they want to study. This protein glows green under UV light, so scientists can quickly hone in on the structure’s location. It will also give the scientists a great view of what the structure looks like and how it is used.

  Importance of Microscopes


Microscopes are vital to the study of cells and biology.

A3.16 Animal Cell Structures
Without the invention of the microscope, scientists would never have been able to discover cells, microorganisms or other structures that are invisible to the naked eye. Cells play a very important role in life functions, without them there would be no life.

Section 2 of this unit will go into more detail about the structures found inside of a cell and their functions. It will focus on how these structures complete the basic functions of life.

  Try This


Crossword Puzzle
Download the PDF version or complete the crossword. This crossword will give you practice with the different microscopes and microscope parts found in this lesson.

View the answers to the crossword puzzle.

1.2 Assignment

Unit 1  Assignment Lessons 2-3


It is now time to complete the Lesson 3 portion of 1.2 Assignment. Click on the button below to go to the assignment page.

1.2 Assignment