AS Biology CIE: The Microscope in Cell Studies

Questions and Answers

What does magnification indicate?

The ratio of the size of the image to the actual size of the specimen (correct)

The number of times the image is smaller than the specimen

The distance between the observer and the specimen

The actual size of the specimen in millimeters

If an object measures 50 μm in actual size and is magnified to 200 mm, what is the magnification factor?

$5000$

$4000$ (correct)

$2500$

$2000$

What is essential when performing calculations for magnification?

Using the same unit for image size and actual size (correct)

Calculating magnification in a specific order

Using only metric measurements

Converting all sizes to centimeters for ease

Which of the following provides a correct example of a measurement unit for cells?

Micrometers (μm) Signup and view all the answers

If an image has a magnification of 1500 and the actual size of the specimen is 0.02 mm, what is the size of the image?

30 mm Signup and view all the answers

What is the total magnification of the specimen when using both the eyepiece and objective lenses?

x400 Signup and view all the answers

How do you convert the image size from millimetres to micrometres?

Multiply by 1000 Signup and view all the answers

What is the average size of a red blood cell in this sample?

7.5 micrometres Signup and view all the answers

If the eyepiece lens magnification were to change to x20, what would the total magnification become?

x800 Signup and view all the answers

What is an essential requirement for specimens viewed under a light microscope?

They need to be thin enough to allow light to pass through. Signup and view all the answers

Why is staining important in slide preparation?

It enhances the visibility of transparent cellular structures. Signup and view all the answers

Which calculation is necessary to find the actual size of the red blood cell from the image size?

Divide the image size by the total magnification Signup and view all the answers

What is the first step in preparing a slide that requires staining?

Air-drying the sample. Signup and view all the answers

What occurs after air-drying a sample for slide preparation?

The sample is heated to fix it to the slide. Signup and view all the answers

What is the primary function of an eyepiece graticule?

To measure the size of an object under a microscope Signup and view all the answers

How is an eyepiece graticule calibrated?

Using a stage micrometer Signup and view all the answers

Which factor does NOT influence the choice of staining method used for specimens?

The color of the microscope's eyepiece. Signup and view all the answers

What is a common characteristic of cellular materials that often require staining for observation?

They are transparent or difficult to distinguish. Signup and view all the answers

What is the value of one graticule division when calibrated using a stage micrometer that has 100 µm divided into 40 divisions?

2.5 µm Signup and view all the answers

Which of the following is NOT a step in preparing a stained slide?

Directly applying a stain without preparation. Signup and view all the answers

What happens to the calibration of the eyepiece graticule when the magnification of the microscope changes?

It needs to be recalibrated Signup and view all the answers

How does the type of cellular material affect slide preparation?

It dictates the method and type of stain utilized. Signup and view all the answers

If an object measures 10 graticule divisions, what is the measured length in micrometres when the magnification factor is 2.5 µm?

25 µm Signup and view all the answers

What is contained within an eyepiece graticule?

A disc with 100 divisions Signup and view all the answers

Why is it necessary to use a stage micrometer alongside an eyepiece graticule?

To provide a reference for accurate measurement Signup and view all the answers

What measurement system is primarily used with the eyepiece graticule?

Micrometres (µm) Signup and view all the answers

What is the primary advantage of using an electron microscope over a light microscope?

It has a greater resolving power and can see smaller structures. Signup and view all the answers

Which of the following statements is true regarding light microscopes?

They can view whole cells and small organisms. Signup and view all the answers

What type of microscope would be best suited for examining viruses?

A transmission electron microscope, for its higher resolution. Signup and view all the answers

What is a limitation of using electron microscopy?

The specimens must be dead. Signup and view all the answers

How do electron microscopes enhance the resolution in imaging compared to light microscopes?

By firing a beam of electrons that has a much shorter wavelength. Signup and view all the answers

What size range of specimens can be effectively examined with light microscopes?

200 nm and above Signup and view all the answers

In electron microscopy, what type of microscopy allows for three-dimensional imaging?

Scanning electron microscopy Signup and view all the answers

Which of the following is NOT a use of electron microscopy?

Observing live cellular processes. Signup and view all the answers

Study Notes

The Microscope in Cell Studies

Microscope slide preparation is essential for detailed observation of cellular material.
Specimens must be thin enough for light to pass through effectively.
Preparation methods vary depending on the type of cellular material being observed.
Staining may be required as many cellular structures are transparent, utilizing stains appropriate for specific specimens.

Magnification Calculations

Magnification (M) indicates how many times larger the image is compared to the actual specimen size.
Magnification can be calculated using the formula: M = I / A, where I is image size and A is actual size.
Measurements must be in consistent units—micrometers (μm) and nanometers (nm) are standard.

Eyepiece Graticules & Stage Micrometers

Eyepiece graticules and stage micrometers are tools used for measuring objects under a microscope.
Calibration of the eyepiece graticule is necessary for each magnification setup, using a stage micrometer with a known scale.
Eyepiece graticule features 100 divisions, requiring calibration to relate graticule divisions to micrometers.
The formula for calculating actual size based on graticule divisions is: measurement (µm) = graticule divisions x magnification factor.

Comparison of Light and Electron Microscopes

Light Microscopes: Effective for specimens larger than 200 nm; utilize light for imaging, suitable for observing live or dead specimens, and ideal for viewing whole cells and small organisms.
Electron Microscopes: Used for specimens larger than 0.5 nm; provide higher resolution due to electron beams instead of light. They are limited to dead specimens and are excellent for studying organelles, viruses, and DNA in detail.

Example Calculation: Size of Red Blood Cells

Given an image size of 3 mm with eyepiece magnification of x10 and objective magnification of x40:
- Total magnification = 10 x 40 = x400.
- Convert image size to micrometers: 3 mm = 3000 μm.
- Actual size of red blood cell is calculated as: 3000 μm / 400 = 7.5 μm.

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Description

Explore the essential concepts of microscopy in cell biology through this quiz. Understand magnification calculations, the use of eyepiece graticules and stage micrometers, as well as resolution techniques. This quiz is ideal for students studying AS Biology CIE.