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Cells and Tissues - Definition, Difference

Think about the different organisms we have read about. 

Now let us list a few;

  • Amoeba
  • Rose plant
  • Cockroach
  • Crow
  • Dog
  • Mango tree
  • Elephant
  • Human being

What is common between all these organisms?

They are all living

And what is a common factor in all living organisms?

They are composed of cells .

In organisms like Amoeba, Paramoecium , Euglena etc. a single cell is responsible for all the life supporting processes like respiration, digestion, movement, excretion etc.

They are single celled or unicellular organisms .

 

On the other hand, organisms like animals, plants and human beings are made of multiple cells and are multicellular organisms .

Millions of cells work are responsible for the life supporting processes in multicellular organisms

They are grouped to perform specialised functions

For example:

In animals - 

  • Muscle cells contract and relax to cause movement
  • Nerve cells carry messages
  • Blood flows to transport oxygen, food, hormones and waste material

In plants-

  • Vascular tissues conduct food and water from one part of the plant to other parts

Cells that are responsible for a particular function are grouped together.

A group of cells that are similar in structure and/or work together to achieve a particular function forms a tissue .

Example - Blood, Phloem, Muscles

 

This means, there is division of labour in multicellular organisms, as a group of cells called tissues are specialised for different activities .

So the levels of organisation in organisms are:

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Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 12 years and a teacher from the past 16 years. He teaches Science, Economics, Accounting and English at Teachoo