The Fundamental Unit of Life Class 9 Notes Science - Chapter 5
What Are The Fundamental Unit Of Life ?
Smallest structural and functional unit of life.
Discovery of cell and its components
- Robert Hooke (1665) first observed dead cells in a cork slice.
- A. V. Leeuwenhoek (1674) discovered free living cells in pond water.
- Robert Brown (1831) discovered the nucleus in the cell.
- Purkinje (1839) coined the term ‘protoplasm’.
- Formated by M.J Schleiden (1838) and Theodor Schwann (1839) expended by R. Virchow (1855) all cells arise from
- All living organisms are made up cells.
- The cells is the basic structural and functional unit in all organisms.
- All cells arise from pre-existing cells.
Types of cells on basis of organization
- Prokaryotic cells organism without definite nucleus of bacteria.
- Eukaryotic cells organisms without definite nucleus, e.g., fungi, plants , animals
Types of organisms on basis of number of cells
- Unicellular (single cell)
- Multicellular (large number of cell)
2.1 Cell Wall (Plant Cell)
- Made up of cellulose, porous to micro and macro moleculose like sugar and starch.
2.2 Cell membrane
- Made up of proteins and lipids.
- Selectively permeable in nature.
- Singer and Nicolson gave the fluid mosaic model of plasma membrane.
2.4 Vacuole (Plant cell)
- Contains water, nutrients, mineral, salts, waste (with greeneous substances)
“Osmosis is a process by which the molecules of a solvent pass from a solution of low concentration to a solution of high concentration through a semi-permeable membrane.”
|Isotonic solution||Same concentration of solutes both inside and outside the cell.||Cell will stay same size|
|Hypertonic solution||Higher solute concentration outside the cell then inside||Cell becomes flaccid or undergoes plasmolysis||Exosmosis|
|Hypotonic solution||Higher solute concentration inside the cell than outside.||Cell becomes turgid or undergoes deplasmolysis||endosmosis|