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Asked by 12kdavy to Amelia, Clem, Izzy, Sarah on 10 Mar 2014.
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Isabel Webb answered on 10 Mar 2014:
Hundreds of millions of years ago, there were only bacteria-like organisms in the world. Over the age of earth, these evolved to become many different things and developed their own ways of surviving. Humans have evolved to survive in one way, whilst bacteria evolved in another. We, for example, have evolved to eat other organisms and get our food that way. Bacteria have evolved to generate energy other ways, such as gathering resources from around them.
Some bacteria have evolved to survive by hijacking others, such as humans, and this leads to disease. And it isn’t just bacteria that do this – there are also fungi, viruses and more that use us as a home. Disease is a side-effect of them using us as a host, and most of the symptoms we feel are actually caused by our bodies fighting the invading bacteria.
So, bacteria exist because they evolved, just as you and I. We evolved in one direction, they evolved in another – evolution doesn’t have a “best way” to do things – and if a new mutation helps survival, it will last. And disease is a result of the survival strategies that some bacteria and other micro-organisms have evolved to use.
But not all bacteria are evil! The bacteria that I work on invade pea plants, but they then work with the pea plants – the peas give them food in return for some of the essential chemicals that the bacteria can make that plants can’t.
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Sarah Harvey answered on 10 Mar 2014:
Bacteria don’t just cause diseases to us, they also cause diseases to plants when they decide that, for example, a nice tomato plant looks like a good place to live!
However as Isabel said, they’re not all bad. Chloroplasts allow plants to convert sunlight into sugar so everyone would agree that they’re pretty essential for feeding everyone on earth! – One theory as to how chloroplasts originated is that they were originally free living photosynthetic bacteria which then got trapped inside plants, so really they’ve been pretty useful over time!
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Clemence Bonnot answered on 10 Mar 2014:
We can add that mitonchondria, that is a part of animal and plant cells, were probably bacteria before to start to live in the future plants and animal cells! These ancient bacteria are very important because they are necessary to produce our energy in a much more efficient way than without them! Therefor, they have helped us to evolve and did it again more than once after that… For example without bacteria in our stomach we would not be able to digest a lots of type of food (milk for example or grass for cows). As in plants, bacteria can be helpful or bad for animals.
And as Isabel said, bacteria existed before plant, fungus or animal cells. A lot of different bacteria exists and live in a vast range of environment where they get their food from (as us). The difference is that we or any big living organism can be an environment to live in for them… Taking up food and producing waste some bacteria disturb our cells activity and make us sick. Plants also fight against aggressive bacteria, you can spot plants responses to bacteria when you see small back spots that looks like burns on a plant leaves… What happens is that the plant try to burn the zone where the bacteria is to isolate it an avoid it spreading. -
anon answered on 11 Mar 2014:
If you think about it, bacteria are just living things like you and me! They grow, eat and multiply when their environment suits them, this may be on your desk, in a plant or nice and cosy in our bodies.
The bacteria don’t try to be nasty, they just want to carry on with what they are doing, this is their life! But like us they also need to poo too, which our bodies aren’t so keen on.
Plants have been shown to effectively kill their cells which contain bacteria to stop them spreading, this is why you might see black spots on the leaves on an ill plant.
As humans our white blood cells attack them, whilst we are feeling ill!
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