Page 89 - Science Class 08

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Structure and Functions of Cells

• About the Cell • Cells are Common to All
• Variety in ells C • Structure of ell a C • Nucleus
• Plant and nimal ells A C

ABOUT THE CELL

Cells are the basic building blocks of all living
things. Cell is a structural and func onal unit of
living organisms.
Cells may be compared to bricks. Bricks are
assembled to make a building. Similarly, cells
are assembled to make the body of every
organism. All organisms are made up of cells.

All basic chemical and physiological func ons Observe the pictures given above. Each picture
of living beings— such as, repair, growth, shows an organism that stands for its class.
movement, immunity, communica on, diges- These organisms have different shapes, sizes
on, etc. are carried out inside the cells. and body-parts. They also carry out their life-

CELLS ARE COMMON TO ALL func ons in different ways. They eat, respire
We have read about various characteris cs of and reproduce in different ways too. But there
living things. All these features are common to is an underlying similarity in their various
various types of organisms–men, animals, birds, shapes and sizes. It is this similarity that binds
rep les, plants, etc. Each of them has organs to all living things together.
perform various func ons— reproduc on, Discovery of the Cell
ea ng diges on, respira on, circula on,
excre on, etc. Robert Hooke, in 1665, observed slices of cork
under a simple magnifying device. Cork is a
Though various organisms have various types
of bodies and differing structures of their part of the bark of a tree. He took thin slices of
organs, each organism is basically made up cork and observed them under a microscope.
of cells.

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