Study Materials

NCERT Solutions for Class 8th Science

 

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Chapter 8. Cell - Structure and functions

Chapter Review

 

 

 

Chapter Review:

  • The structural and functional unit of the living organism is called cell.

  • Cells were first observed in cork by Robert Hooke in 1665.

  • The smallest living part of an organism is a ‘cell’.

  • Cells exhibit variety of shapes and sizes.

  • The organism which is made of only one cell that is called unicellular organism. Ex : amoeba and paramecium. 

  • The organism which is made of more than one cell are called multi cellular organism. Ex : human and tree. 

  • A tissue is a group of similar cells having a specific function

  • The nucleus contains thread-like structures called chromosomes. 

  • Genes control the transfer of hereditary characteristic from parent to offspring; it is carried by the chromosomes. 

  • Green colour plastid is called chloroplast.

  • The nerve cell receives and transfers messages, thereby helping to
    control and coordinate the working of different parts of the body.

  • The smallest cell is 0.1 to 0.5 micrometre in bacteria. The largest
    cell measuring 170 mm ×130 mm, is the egg of an ostrich.

  • Gene is a unit of inheritance in living organisms. It controls the transfer of a hereditary characteristic from parents to offspring.

  • Nucleus is separated from the cytoplasm by a membrane called the nuclear membrane.

  • The cells having nuclear material without nuclear membrane are termed prokaryotic cells.Examples are bacteria and blue green algae.

  • The cells, like onion cells and cheek cells having well organised nucleus with a nuclear membrane are designated as eukaryotic cells.

  • They are scattered in the cytoplasm of the leaf cells. These are called plastids.

  • Coloured bodies called plastids are found in the plant cells only.

  • Green plastids containing chlorophyll are called chloroplasts.

 

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