NCERT Solutions for Class 11 Biology Chapter 8 Cell: The Unit of Life to Study online without download or download in PDF form free. CBSE Solutions of other subjects for UP board, MP board, CBSE and other boards following NCERT Books as a course book is available to download.
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NCERT Solutions for Class 11 Biology Chapter 8
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Cell: The Unit of Life: Solutions
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Important Notes on Cell: The Unit of Life
- Modification of cell envelope
- Slime layer: Clycocalyx in form of loose sheath.
- Capsule: Glycocalyx in form of thick and tough sheath.
- Mesosomes: Extension of plasma membrane. These can be in the form of vesicles, tubules and lamellae.
- It is not covered by nuclear envelope. In addition to the genomic DNA (the single chromosome/circular DNA), many bacteria have small circular self-replicating, double stranded DNA which is called as plasmid, plasmid contain genes like antibiotic resistance.
- Cell Membrane-Singer and Nicolson (1972) gave fluid mosaic model.
According to this the quasi-fluid nature of lipid enables lateral movement of proteins within the overall bilayer; two types of proteins (Peripheral and integral proteins) with cholesterol, glycolipids and glycoproteins. Erythrocyte membrane has 52% protein and 40% lipids.
- It is non-living rigid structure which gives shape to the cell and protects cell from mechanical damage and infection, helps in cell-to-cell interaction and provides barrier to undesirable macromolecules.
- Cell wall of algae is made of cellulose, galactans, mannans and minerals like calcium carbonate. Plant cell wall consists of cellulose, hemicellulose, pectins and proteins.
- First observed by Camillo Golgi (in 1898)
- Consist of cisternae stacked parallel to each other. Two faces of the organelle are convex/cis or forming face and concave/trans or maturing face.
- Functions: Performs packaging of materials, to be delivered either to the intra-cellar targets or secreted outside the cell. Important site of formation of glycoproteins and glycolipids.
- Membrane bound vesicular structures formed by the process of packaging in the golgi apparatus. Contain hydrolysing enzymes (lipases, proteases, carbohydrates) which are active in acidic pH. Also called Suicidal Bag.
- Function: Intracellular digestion.