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Required Practical: Microscopy
MICROSCOPES are tools that allow us to see the unseen world, revealing structures too small for the naked eye.
There are TWO different types of microscopes, each with its own capabilities:
- LIGHT MICROSCOPES use light and lenses to magnify specimens, allowing us to see individual cells and large subcellular structures like NUCLEI.
- ELECTRON MICROSCOPES use electrons to form an image and can magnify much more than light microscopes. They show us the finer details of cell structures like MITOCHONDRIA and CHLOROPLASTS.
Magnification
- MAGNIFICATION is how much larger the microscope makes the object appear.
- To calculate magnification, use the formula:
Working with Standard Form
- Microscopes can see very tiny objects, and for this, we often use numbers in STANDARD FORM to handle very large or small numbers.
- To write in standard form, move the decimal point until there's one non-zero digit to the left, then multiply by a power of 10. The power of 10 is positive if the decimal point is moved to the left, and negative if it's moved to the right.
Microscope Calculations
- When solving problems involving microscope measurements, ensure the units are consistent.
- Make sure you know how to convert from Micrometres to Millimetres.
Here is an example of a calculation:
Labelling a Microscope
Preparing and Observing Slides
Slide Preparation: Viewing Onion Cells
- Start with a clean microscope SLIDE.
- Add a single DROP OF WATER to the slide.
- Carefully cut an onion and separate it into layers.
- With TWEEZERS, peel off a piece of the EPIDERMAL tissue and place it onto the drop of water on your slide.
- Add a drop of IODINE SOLUTION as a stain to highlight cell features.
- Place a COVER SLIP over the specimen carefully to avoid air bubbles which can obstruct the view.
Using a Light Microscope
- Secure the slide on the stage of the microscope.
- Begin with the LOWEST-POWERED OBJECTIVE LENS.
- Adjust the COARSE ADJUSTMENT KNOB to bring the stage close to the lens without it touching.
- Look through the EYEPIECE and use the COARSE ADJUSTMENT KNOB to find the focus.
- Fine-tune the focus with the FINE ADJUSTMENT KNOB for a clear image.
- For greater detail, switch to a higher-powered objective lens and refocus.
Drawing Observations
- Draw what you observe with a PENCIL.
- Ensure the drawing occupies at least half of the space provided.
- Use clear, UNBROKEN LINES, and avoid coloring or shading.
- Draw cells proportionally, labelling important features like the nucleus or chloroplasts with straight lines.
- Include a TITLE and the MAGNIFICATION LEVEL.
Required Practical: Microscopy
MICROSCOPES are tools that allow us to see the unseen world, revealing structures too small for the naked eye.
There are TWO different types of microscopes, each with its own capabilities:
- LIGHT MICROSCOPES use light and lenses to magnify specimens, allowing us to see individual cells and large subcellular structures like NUCLEI.
- ELECTRON MICROSCOPES use electrons to form an image and can magnify much more than light microscopes. They show us the finer details of cell structures like MITOCHONDRIA and CHLOROPLASTS.
Magnification
- MAGNIFICATION is how much larger the microscope makes the object appear.
- To calculate magnification, use the formula:
Working with Standard Form
- Microscopes can see very tiny objects, and for this, we often use numbers in STANDARD FORM to handle very large or small numbers.
- To write in standard form, move the decimal point until there's one non-zero digit to the left, then multiply by a power of 10. The power of 10 is positive if the decimal point is moved to the left, and negative if it's moved to the right.
Microscope Calculations
- When solving problems involving microscope measurements, ensure the units are consistent.
- Make sure you know how to convert from Micrometres to Millimetres.
Here is an example of a calculation:
Labelling a Microscope
Preparing and Observing Slides
Slide Preparation: Viewing Onion Cells
- Start with a clean microscope SLIDE.
- Add a single DROP OF WATER to the slide.
- Carefully cut an onion and separate it into layers.
- With TWEEZERS, peel off a piece of the EPIDERMAL tissue and place it onto the drop of water on your slide.
- Add a drop of IODINE SOLUTION as a stain to highlight cell features.
- Place a COVER SLIP over the specimen carefully to avoid air bubbles which can obstruct the view.
Using a Light Microscope
- Secure the slide on the stage of the microscope.
- Begin with the LOWEST-POWERED OBJECTIVE LENS.
- Adjust the COARSE ADJUSTMENT KNOB to bring the stage close to the lens without it touching.
- Look through the EYEPIECE and use the COARSE ADJUSTMENT KNOB to find the focus.
- Fine-tune the focus with the FINE ADJUSTMENT KNOB for a clear image.
- For greater detail, switch to a higher-powered objective lens and refocus.
Drawing Observations
- Draw what you observe with a PENCIL.
- Ensure the drawing occupies at least half of the space provided.
- Use clear, UNBROKEN LINES, and avoid coloring or shading.
- Draw cells proportionally, labelling important features like the nucleus or chloroplasts with straight lines.
- Include a TITLE and the MAGNIFICATION LEVEL.
