How Plants and Animals Are Organized – Living Organisms – KS3 Biology – BBC Bitesize

VOICE OFF: Multicellular organisms are organized into increasingly complex parts…

Cells. Fabrics. Organs. organ systems. And the organism itself.

Cells are the building blocks of life. Tissues are made when specialized cells with the same function come together.

For example, millions of muscle cells make up muscle tissue.

An organ is made up of two or more tissues, which all work together to do a particular job, like the heart in animals or a leaf in a plant.

An organ system is made up of a group of organs that all work together to do a particular job, such as the nose, trachea, bronchi, and lungs that all make up the gas exchange system.

Mr Shribman: Yes, so one of the systems in the human body is the digestive system. Ours is simpler than that of some other animals, like cows and deer have multiple stomachs, we only have one.

Gethin: So, as you can see, there are many tissues and organs that make up our digestive system, but what is the difference between them?

Mr Shribman: So, yes, these are key parts of your school curriculum.

First of all, you need to know that a tissue is a group of cells in the same place all doing the same thing. There are lots of cells in your mouth that produce saliva. Imagine if the tissue that makes saliva disappeared completely – you would have the driest mouth in the world.

Gethin: I get that sometimes when I’m nervous on TV, but anyway, how about an organ, then?

Mr Shribman: So the organs are these things here like the stomach and the liver. They do a comprehensive job. There is an amazing organ called the spleen, which can help you hold your breath underwater longer if you have a really big one.

Penguins have massive spleens.

Either way, you should know that an organ is a group of different tissues working together to achieve an overall goal.

Gethin: OK understood. So we know what a tissue and an organ are. What about a system?

Mr Shribman: A system is a group of organs that work together to accomplish an overall task. Our nervous system is therefore our brain and all our nerves, and it allows us to think, to feel, to move, to dance, etc.

Our digestive system allows us to eat delicious food, to digest it – which means to break it down and absorb it.

Speaking of which, there’s a guy in France who once ate an entire airplane by breaking it into small pieces, but I wouldn’t recommend that at all.

Gethin: Is it true? It’s amazing ! OK, I definitely wouldn’t do that. All right, so a little recap for us on that.

Mr Shribman: So to recap, cells make tissues, tissues make organs, and organs make systems. Some living things are made up of a single cell. We call them unicellular – like a unicycle but with one cell – and they don’t have to worry about all that because they’re just one cell.

We are multicellular, which means that lots of cells together miraculously form working human beings like us.