18 Electron microscopy

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

The possibility to enlarge a sample substantially more

It's cheaper

It requires less maintenance

Light microscopes use light for magnification. Since the wavelength of visible light is between 400-800nm, it is almost impossible to enlarge a sample beyond that. The wavelength of an electron is many times smaller, so you can enlarge much smaller objects.

What happens when an electron beam irradiates a sample in a scanning electron microscope?

The sample emits electrons and X-rays

The sample emits gamma rays and neutrinos

The sample emits protons

An electron beam is passed over the sample (scanning). This emits so-called secondary electrons from the sample, which are recorded by a detector. An image corresponding to the topography of the sample is then generated. The emitted X-rays can be detected with the help of another detector, from which information about the chemical composition of the sample can be obtained.

In the middle of the picture you can see a grain of pollen. Plants produce different forms of pollen grains, depending on the type of pollination (wind, insects, ...) which is to take place.

The eyes of insects consist of up to 28,000 single eyes.The spatial resolution is less good than that of the human eye. However, flying insects have a temporal resolution of 250 frames per second, as they often require a high reaction speed. The human eye only sees 24 frames per second, and in addition, insect eyes have a larger field of view.

This is what cellulose looks like at 400 times magnification. Where is cellulose mainly found?

In the plant cells

In the animal cells

In the yeast cells

Cellulose is the most important building material of nature. It is mainly found in trees (wood) and cotton. We humans then make paper, clothing or cotton wool from it.

They provide oxygen transport in our bodies. This image taken with the electron microscope was subsequently colorized with the help of an image processing program. An electron microscope sees no colors, only emitted electrons.

This is Tyvek. What makes this material so special?

It is biodegradable and tear-resistant

It is air permeable and waterproof

It is self-healing

Tyvek is produced in Contern, Luxembourg. The fibrous structure of the Tyvek allows gas exchange (e.g. air), but is impermeable to liquids.

Several sperm cells can dock to the egg cell, but only one can enter.

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3 Luxembourg Science Center

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6 eyeofscience.de

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