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NAVODAYA VIDYALAYA SAMITI, NOIDA

E-CONTENT PREPARATION

FOR CLASS 9TH SCIENCE

CHAPTER: 5

THE FUNDAMNTAL UNIT OF LIFE

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BY

Heera Harimadhavan, PGT Biology

JN Wayanad, Kerala

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Learning objectives

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What makes us different from a non living thing?

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How are we different from a table or a rock?

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Which is the basic component of your body which participates in all of the above processes?

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THE FUNDAMENTAL UNIT OF LIFE

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CELL

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WHAT IS CELL?

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Cell is defined as the structural and functional unit of life.

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3 common features in all cells

  • PLASMA MEMBRANE

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  • NUCLEUS

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  • CYTOPLASM

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PLASMA MEMBRANE

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Plasma membrane allows cell to exchange materials with surroundings

  • The cell uses simple processes for exchange of oxygen, carbon dioxide, water.

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  • The processes used are diffusion and osmosis.

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Diffusion:

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SOLUTION

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Structural strength in plants is because of cell wall

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Cell walls are present in:

  • Plants
  • Fungi
  • Bacteria

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NUCLEUS

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  • The nucleus plays central role in cellular reproduction.
  • It determines the way the cell will develop and form it will exhibit at maturity.
  • It directs the chemical activities of the cell.

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CELL ORGANELLES

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ENDOPLASMIC RETICULUM

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Plastid -Kitchen of the cell

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CELL DIVISION

  • New cells are formed in organisms

- to grow

- to replace old

- to form gametes for reproduction

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TYPES OF CELL DIVISION

MITOSIS

  • Two daughter cells formed.
  • Same number of chromosomes as mother cell.
  • Helps in growth and repair in organisms.

MEIOSIS

  • Four daughter cells are formed.
  • Half the number of chromosomes as mother cells.
  • Helps in formation of gametes.

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Let's recollect.......

  • Cell
  • Cell discovery
  • Cell theory
  • 3 main features of any cell
  • Differentiate between prokaryotic and eukaryotic cell.
  • Fate of plant and animal cells in different solutions.
  • Role of osmosis and diffusion
  • Cell organelles and respective functions.
  • Types of cell division.

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