Cell the unit of life 70 MCQ/neet 2026 🔥/ncert line by line MCQ practice 🔥/score booster series 🔥🤯 скачать в хорошем качестве

Cell the unit of life 70 MCQ/neet 2026 🔥/ncert line by line MCQ practice 🔥/score booster series 🔥🤯

“Cell: The Unit of Life” (Class 11 NCERT – NEET level): Cell – The Unit of Life The cell is the basic structural and functional unit of life. All living organisms are made up of one or more cells. The branch of biology that studies cells is called Cytology. Discovery of Cell Robert Hooke (1665) discovered cells in a thin slice of cork and coined the term cell. Leeuwenhoek observed living cells under a microscope. Robert Brown (1831) discovered the nucleus. Cell Theory Proposed by Schleiden and Schwann (1838-39): All living organisms are composed of cells. Cell is the basic unit of life. Later, Rudolf Virchow (1855) added: 3. All cells arise from pre-existing cells. Types of Cells 1. Prokaryotic Cell No true nucleus (genetic material is naked). No membrane-bound organelles. Example: Bacteria, Cyanobacteria. Small in size (1–10 µm). 2. Eukaryotic Cell True nucleus present. Membrane-bound organelles present. Example: Plant and Animal cells. Larger in size (5–100 µm). Structure of a Cell 1. Plasma Membrane Outer covering of the cell. Made of lipid bilayer (Fluid Mosaic Model – Singer & Nicolson). Selectively permeable. 2. Cell Wall (Plants only) Made of cellulose. Provides shape and protection. 3. Cytoplasm Jelly-like substance. Contains organelles. 4. Nucleus Control center of the cell. Contains DNA. Surrounded by nuclear membrane. Cell Organelles and Their Functions Mitochondria – Powerhouse of the cell (ATP production). Ribosomes – Protein synthesis. Endoplasmic Reticulum (ER) RER – Protein synthesis SER – Lipid synthesis Golgi Apparatus – Packaging and secretion. Lysosomes – Suicidal bags (intracellular digestion). Plastids (Plants only) Chloroplast – Photosynthesis Chromoplast – Pigments Leucoplast – Storage Vacuole – Storage (large in plant cells). Important NEET Points Mitochondria and chloroplast have their own DNA. Ribosomes are non-membranous. Cell membrane follows Fluid Mosaic Model. Prokaryotes lack membrane-bound organelles. Plant cells have cell wall and large central vacuole.