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Cell Biology

Cell structure, organelles, cell division, biomolecules

Key Concepts
  • Prokaryotic cells: no membrane-bound nucleus; no membrane-bound organelles
  • Eukaryotic cells: membrane-bound nucleus; compartmentalised organelles
  • Cell membrane: fluid mosaic model — phospholipid bilayer with embedded proteins
  • Mitosis: 4 stages (PMAT); produces 2 identical daughter cells
  • Meiosis: 2 divisions; produces 4 haploid gametes with genetic variation
Important Formulae
Cell cycle phases G₁ → S (DNA replication) → G₂ → M (mitosis)
Meiosis result 1 diploid cell (2n) → 4 haploid cells (n)
Quick Tips
  • Ribosome: site of protein synthesis; 70S in prokaryotes, 80S in eukaryotes.
  • Mitochondria and chloroplasts have their own DNA and ribosomes — support endosymbiont theory.
  • Osmosis: water moves from low solute concentration (high water potential) to high solute concentration.
Sample Practice Questions

  1. The fluid mosaic model of cell membrane was proposed by:

    • Watson and Crick
    • Singer and Nicolson
    • Schleiden and Schwann
    • Virchow
    Show answer

    Answer: Singer and Nicolson

  2. Cell wall in plants is primarily made of:

    • Chitin
    • Cellulose
    • Peptidoglycan
    • Lignin
    Show answer

    Answer: Cellulose

  3. The powerhouse of the cell is:

    • Nucleus
    • Ribosome
    • Mitochondria
    • Golgi apparatus
    Show answer

    Answer: Mitochondria

  4. Active transport differs from passive transport in that it:

    • Moves with concentration gradient
    • Requires ATP energy and moves against concentration gradient
    • Uses no energy
    • Requires no carrier proteins
    Show answer

    Answer: Requires ATP energy and moves against concentration gradient

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Practice Questions

Practice 20 randomly selected NEET questions on Cell Biology. Answers are revealed after each question.

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