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LIVING THINGS

 To know something about cells watch the video 

 


Microscopes magnify the image of an object many times. By using them we could realize that living things are made up of many tiny parts called cells. To Know how big are cells click on the microscope  

                                                           Onion cells 

                                                                      

   

Click on the drawing to listen to a RAP that shows you the parts of a cell.  

Animal cells and plant cells have similarities and differences 

Cells are the basic units of life. They carry out the three basic life processes:

Nutrition: Cells obtain nutrients and energy from food.

(In the next video, go to minute 5:20)

 White blood cells defend our bodies by eating harmful bacteria and viruses of our body.

Reproduction: Cells can divide and produce new cells that are identical to themselves.

Sensitivity: Cells react to what they perceive around.

 

Multicellular living things are made up of many different types of cells. Similar cells that carry out a common function are grouped together to form a tissue. Look at this picture of the stomach.

Different tissues are organized to form organs. The stomach is an organ.

Organs form systems. Systems are made up of a group of organs that work together to carry out a common function. For example, the stomach works together with other organs (mouth, oesophagus, liver, intestine...) to form the digestive system, whose function is the digestion and assimilation of nutrients.

Finally, when all systems work together, they form an organism. You, a tree and a whale are organisms.

Within multicellular organisms like animals and plants there are differences as regards their cells.

Besides plants and animals, living things are classified into other three kingdoms: fungi, bacteria and the so called "fifth" kingdom.

Fungi:

Bacteria are the most abundant of all living things and also the smallest. For this reason they are called microorganisms or microbes. Bacteria are unicellular and can live in different environments. Some of them are helpful and some harmful.

The next video shows how our body protects us against the attack of harmful bacteria.

The fifth kingdom is made up of all the living things that are not included in the previous kingdoms. They can be:

1.Protozoa: unicellular microbes that feed on other living things (including other protozoa, as shown on the next video).

 

2.Algae: like plants, they make their own food. Many algae are formed by a single cell, but others are multicellular and can be very large.

Viruses are so small and simple that scientists cannot agree if they are living things or not. Viruses cause illnesses like influenza, measles, chicken pox, AIDS or flu.