HBSE 9th Class Science Notes Chapter 5 The Fundamental Unit of Life

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.

HBSE 9th Class Science Notes Chapter 5 The Fundamental Unit of Life

→ 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.

HBSE 9th Class Science Notes Chapter 5 The Fundamental Unit of Life

→ 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.

HBSE 9th Class Science Notes Chapter 5 The Fundamental Unit of Life

→ 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.

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