Haryana State Board HBSE 9th Class Science Notes Chapter 5 The Fundamental Unit of Life Notes.
Haryana Board 9th Class Science Notes Chapter 5 The Fundamental Unit of Life
→ The structural and functional unit of living organisms is called a cell.
→ Robert Hooke discovered the cell in 1665.
→ A cell can be seen under a microscope.
→ Amoeba and paramoecium are unicellular organisms.
→ Multicellular organisms evolved from unicellular organisms.
→ Leeuwenhoek discovered bacteria in 1674 through a microscope.
→ Robert Brown found the nucleus of the cell in 1831.
→ J.E. Purkinje discovered protoplasm in 1839.
→ M.J. Schleiden (1838) and T. Schwann (1839) put forward the cell theory.
→ Virchow further expanded the cell theory in 1855.
→ The complex structural organisation of the cell was studied after the invention of electron microscope in 1940.
→ Division of labour is found in multicellular organisms.
→ All animal cells have plasma membrane.
→ Plant cells have cell wall.
→ Plasma membrane shows diffusion.
→ Osmosis is a kind of diffusion.
→ Nucleus controls the activities of the cell.
→ The indistinct nucleus in bacteria is called nucleoid.
→ The fluid enclosed by plasma membrane is called cytoplasm.
→ Cytoplasm and nucleus together constitute a protoplasm.
→ Endoplasmic reticulum is a large network of membrane-bound tubes.
→ Camillo Golgi described the Golgi apparatus.
→ Lysosome disposes off the waste products of the cell.
→ Mitochondria is the ‘powerhouse’ of the cell.
→ Plastids are found only in the plant cells.
→ Vacuoles are storage sacs for solid or liquid contents.
→ Cell: Cell is the structural and functional unit of living organisms.
→ Unicellular organisms: The organisms whose body is formed of only one cell is called unicellular organisms.
→ Multicellular organisms: The organisms formed of many cells grouped together are called multicellular organisms.
→ Division of labour: Different parts of the human body perform different functions, this is called division of labour.
→ Plasma membrane: The outer covering of the cell, which is made up of lipids and protein, and covers the cell from outside is called plasma membrane.
→ Osmosis: The movement of water molecules through a selectively permeable membrane is called osmosis.
→ Absorption: The absorption of minerals and water by the cells is called absorption.
→ Endocytosis: The procurement of food and other substances from outer environment in unicellular organisms is called endocytosis.
→ Nucleus: The circular structure in the centre of the cell, which controls the activities of the cell, is called nucleus.
→ Nucleoid: The indistinct nuclear region in the cell is called nucleoid.
→ Prokaryotic cells: Cells having no cell organelles and with only one chromosome are called prokaryotic cells.
→ Eukaryotic cells: Cells having cell organelles and more than one chromosome are called eukaryotic cells.
→ Cytoplasm: The fluid enclosed by the cell membrane is called cytoplasm.
→ Protoplasm: Cytoplasm and nucleus together constitute protoplasm.
→ Endoplasmic Reticulum: It is a large network of membrane-bound tubes.
→ Golgi Apparatus: It is a system of membrane-bound vesicles arranged almost parallel to each other in stacks.
→ Lysosome: Powerful digestive enzymes which are enclosed by a membrane constitute a lysosome.
→ Mitochondria: The cell organelles which produce energy are called mitochondria.
→ Vacuoles: Storage sacs for solid or liquid substances are called vacuoles.