Chapter Review:
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The structural and functional unit of the living organism is called cell.
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Cells were first observed in cork by Robert Hooke in 1665.
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The smallest living part of an organism is a ‘cell’.
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Cells exhibit variety of shapes and sizes.
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The organism which is made of only one cell that is called unicellular organism. Ex : amoeba and paramecium.
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The organism which is made of more than one cell are called multi cellular organism. Ex : human and tree.
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A tissue is a group of similar cells having a specific function
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The nucleus contains thread-like structures called chromosomes.
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Genes control the transfer of hereditary characteristic from parent to offspring; it is carried by the chromosomes.
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Green colour plastid is called chloroplast.
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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.
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Nucleus is separated from the cytoplasm by a membrane called the nuclear membrane.
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The cells having nuclear material without nuclear membrane are termed prokaryotic cells.Examples are bacteria and blue green algae.
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The cells, like onion cells and cheek cells having well organised nucleus with a nuclear membrane are designated as eukaryotic cells.
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They are scattered in the cytoplasm of the leaf cells. These are called plastids.
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Coloured bodies called plastids are found in the plant cells only.
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Green plastids containing chlorophyll are called chloroplasts.