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VIKING SCIENCELearning Objective:
To identify, describe and classify micro-organisms.
I’m studying the science of the Vikings. What I’ve learned about them shows that they have been misrepresented and
misunderstood as a primitive civilisation.I need your help to prove that the Vikings were much more
than marauding warriors!
Large Viking communities had drinking halls, where large quantities of beer and mead – produced by fermenting ingredients – were consumed. Did you know that they also used fermentation to make bread, and
yogurt and cheese?
The Vikings had knowledge of the process of
fermentation to produce food and drinks.
What is fermentation?
Fermentation is a helpful chemical reaction in foods and drinks that is caused by tiny micro-organisms ‘eating’, or ‘breaking down’ the sugars or carbohydrates in them. It’s helpful because it changes the food, killing harmful bacteria and making it last longer. Fermentation can also make foods and drinks tastier.
Certain types of fermentation produce alcohol, which the Vikings enjoyed drinking in large quantities!
Beer was drunk every day in Viking society, especially by sailors. They relied on it at sea, where they could not get fresh drinking
water.Mead was often drunk on special occasions. At these times, Alcohol was not served by slaves or servants, but by the most important
person present. It was a big responsibility and an honour!
What are micro-organisms*?
*Micro-organisms are called microorganisms (no hyphen) in the USA and other parts of the world. They are often referred to as microbes, too. Viruses may be referred to as microbes as they can help or harm humans in similar ways. However, viruses are not microbes or micro-organisms – they do not share the characteristics of living things. They are sometimes said to be ‘on the edge of life’.
Micro-organisms are tiny, single-celled living things that we can only see using a microscope or other scientific apparatus.
Micro-organisms are everywhere! You have trillions of micro-organisms living inside you and on your skin. They live in the food we eat, the water we drink and
the clothes we wear.Although many micro-organisms are too small to photograph, scientists are able
to create images which represent micro-organisms.
Far left: Computer generated images of several different types of
micro-organisms.Left: A photograph of microscopic
bread mould – a type of micro-organism.
Micro-organisms seem very strange when compared to larger living things which we have had more opportunities to observe. Some of them behave a bit like plants. Others behave more like animals. Some aren’t very much like
living things at all.Let’s take a look at some of the micro-organisms all around us:
Cyanobacteria are found in fresh water and sea water. They use
photosynthesis to make their own food, a bit like plants do.
We can’t see individual cyanobacteria without a microscope, but we can see when billions of them form on
the surface of ponds!
Left: A red blood cell, approximately proportionate to the image below.
Below: Trypanosoma brucei, a protist which is found in insects and transmitted to humans when insects
bite them. It has a tail-like structure called a flagellum which it uses to swim forward.
Below: Toxoplasma gondii, a protist which likes to live and reproduce in cats, particularly. It can be transmitted to humans through contact with cat
feces (poo), and make us feel unwell.
Protists are micro-organisms which behave a bit more like animals. They have tail-like structures or tiny hairs which they use to help them move (by whipping or
waving them). They may eat other micro-organisms by surrounding and absorbing them, or
‘eating’ them with mouth-like structures. Some have very simple stomachs which dissolve the food they eat.
Bacteria are amazing! They are everywhere, and they are very important for all life on earth. For example, all dead plants and animals are broken down by bacteria, enriching the soil and
producing nutrients for new life. Scientists estimate that the total weight of all bacteria on earth is greater than the weight of all other living things!
Did you know that the human body is made up of around 30 trillion cells? That’s nothing – on average, adult humans have 39 trillion bacteria living inside them – mostly in their stomachs!
Below: Lactobaccilus. Species of this bacteria are found in humans, and believed to be important for keeping us healthy. Other species are important for
producing foods such as yogurt and cheese.
Below: Streptococcus pneumoniae. Bacteria can be rod-shaped, spherical, spiral-shaped or chain-
shaped, like this one. Streptococcus pneumoniae is very harmful to humans. What illness do you think it
causes?
Did you know that mushrooms are not actually vegetables? They belong to a group of organisms called fungi. The mushrooms we eat, or see growing wild are made of millions of cells. Some fungi are made of only a single cell. Single-celled fungi are the largest type of single-celled micro-organisms. They’re the easiest to
see using a microscope. Single-celled fungi are called yeasts.
Left: Baker’s yeast under the microscope. Yeast cells reproduce in an interesting way. Here they are ‘budding’, meaning that new cells grow
while they are still attached to the outside of their parent cell. When they have grown enough, they separate.
Below: Some yeasts grow and reproduce on our skin, under our nails and around our orifices. They can cause infections such as cold sores.
The system of organising living things is
called ‘taxonomy’.
We organise, or classify, all living things by grouping them according to shared characteristics. These groups have many other groups within them, which we can
show using branching diagrams or keys. Can you think of any species of living thing that are organised into each of these top-level groups, or kingdoms?
Bacteria Plants Fungi AnimalsProtists
That was tricky! You may be more familiar with the kingdoms of plants and animals than the others. Micro-organisms are found in the kingdoms of bacteria,
protists and fungi. Each kingdom is organised into smaller and smaller groups until you get to species; the bottom level.
Here’s an example of a classification key showing how humans are classified:
There’s another way in which we tend to classify micro-organisms:
whether they are helpful, unhelpful or even harmful. The micro-organisms involved in the fermentation of food are helpful. Do you know how
fermentation works? If you don’t know for sure, do you have any ideas?
Do you know of any ways in which micro-organisms are harmful in food and food production? Have you ever noticed changes in foods that might be a result of the activity of micro-
organisms?
Today we’re going to identify, classify and describe
micro-organisms as we learn about how they were helpful and harmful for the vikings.
