class 9 cell chapter notes ncert
Class 9 Cell Chapter Notes Class 9 Science: Cell Chapter Notes 1. What is a Cell? The cell is the basic unit of life, often called the building block of organisms. All living organisms are made of cells. Cells can be of two types: Prokaryotic (without a true nucleus) and Eukaryotic (with a true nucleus). 2. Discovery of Cells Cells were first discovered by Robert Hooke in 1665 when he observed a slice of cork under a microscope. Anton van Leeuwenhoek later observed living cells in pond water. 3. Cell Theory The Cell Theory states: All living organisms are made up of cells. The cell is the basic unit of structure and function in living things. All cells arise from pre-existing cells. (Proposed by Rudolf Virchow ) 4. Types of Cells Prokaryotic Cells : These are simple cells without a nucleus (e.g., Bacteria). Eukaryotic Cells : Thes...
