Microscopy

In biology, we often study extremely small structures like cells that cannot be seen with the naked eye. Microscopes are essential tools for this, and their quality depends on two main features:

• Magnification: The ability to make objects appear larger.

• Resolution: The ability to distinguish between two close points, creating a sharper image.

Comparing magnification and resolution

Light and electron microscopes

Light Microscopes: First developed in the late 16th century, these microscopes use light and glass lenses to magnify images. Although they have relatively low magnification and resolution, they allow us to observe basic cell structures like the nucleus, vacuoles, and chloroplasts.

A light microscope

Electron Microscopes: Invented in the early 20th century, electron microscopes use electrons instead of light and electromagnets instead of lenses. They offer much higher magnification and resolving power than light microscopes, allowing scientists to study cells in much finer detail. This advanced resolution has enabled biologists to see and understand sub-cellular structures such as mitochondria, ribosomes, and even viruses.

Additional maths skills

In microscopy, magnification can be calculated using the formula:

  magnification = size of image / size of real object

In this formula:

• Size of image is how large the object appears under the microscope.

• Size of real object is the actual size of the object being viewed.

When biologists observe and draw what they see under a microscope, the drawing represents the image, and the real object is the actual cell or structure. The magnification shows how much the object has been enlarged in the drawing.

Additional maths skills (Higher tier only)