Aspirant Academy

Science and Technology

Key Points at a Glance

Biology: Cell, Plant Parts, Nutrition/Reproduction, Human Physiology, Food/Nutrition, Immunity/Diseases, Microbes, Fermentation, Biotech/Genetic Engineering, GMO Ethics, Vaccines/CRISPR/mRNA, Artificial Organs

Paper II · Unit 2 Section 1 of 13 0 PYQs 31 min
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Key Points at a Glance

  1. Cell — Basic Unit of Life

    • Prokaryotic cells (bacteria, archaea) lack a membrane-bound nucleus and organelles
    • Eukaryotic cells (plants, animals, fungi) have a true nucleus and membrane-bound organelles
    • Eukaryotic organelles include mitochondria, endoplasmic reticulum, and Golgi apparatus

  2. Photosynthesis

    • Equation: 6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂
    • Occurs in chloroplasts — light-dependent reactions in thylakoids; Calvin cycle (dark reactions) in stroma
    • Chlorophyll a and b absorb red and blue light; reflect green

  3. Human Digestive System

    • Mouth (amylase — starch) → stomach (pepsin, HCl — proteins) → small intestine (lipase — fats; trypsin — proteins; bile from liver) → large intestine (water absorption)
    • Insulin from beta cells of pancreas lowers blood glucose
    • Glucagon from alpha cells raises blood glucose

  4. Blood Groups — ABO System

    • Discovered by Karl Landsteiner, 1900 (Nobel 1930)
    • A (antigen A, antibody b), B (antigen B, antibody a), AB (both antigens, no antibody — "universal recipient"), O (no antigens, both antibodies — "universal donor")
    • Rh incompatibility in pregnancy causes haemolytic disease of the newborn

  5. Immunity

    • Innate immunity — non-specific: skin barrier, phagocytes, inflammation, fever
    • Adaptive immunity — specific: B lymphocytes produce antibodies (humoral); T lymphocytes attack infected cells (cell-mediated)
    • Memory cells enable faster response on re-exposure — the basis of vaccination

  6. Vaccines

    • Introduce weakened/killed pathogens or antigens to prime immune memory without causing disease
    • Types: Live attenuated (BCG for TB, OPV for polio), Inactivated (IPV, flu), Subunit (Hepatitis B)
    • mRNA vaccines (Pfizer-BioNTech BNT162b2, Moderna mRNA-1273) — first approved for COVID-19 in December 2020

  7. CRISPR-Cas9

    • Derived from a bacterial immune system; repurposed as a gene editing tool
    • Developed by Jennifer Doudna and Emmanuelle Charpentier — Nobel Prize Chemistry 2020
    • A guide RNA directs Cas9 protein to cut DNA at a specific sequence, enabling insertion, deletion, or replacement of genes

  8. Genetically Modified Organisms (GMOs)

    • Organisms whose DNA is altered using genetic engineering
    • Bt cotton (Bacillus thuringiensis toxin gene) — India's first approved GMO crop (2002); ~90% of India's cotton cultivation; reduced insecticide use by 40%
    • Controversy: Bt brinjal — GEAC approved 2010, moratorium imposed; Golden Rice stalled due to opposition

  9. Fermentation

    • Anaerobic breakdown of organic matter by microbes
    • Alcoholic fermentation: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ (yeast Saccharomyces cerevisiae) — beer, wine, bioethanol, bread
    • Lactic acid fermentation: glucose → lactic acid (bacteria) — yogurt, cheese, silage

  10. Biotechnology

    • WHO definition: application of biological systems and organisms to develop products and processes
    • Traditional biotech: selective breeding, fermentation; Modern biotech: recombinant DNA, gene editing, tissue culture, bioreactors
    • India's biotech sector valued at $137 billion (2023); target $300 billion by 2030 under National Biotechnology Strategy

  11. Artificial Organs and Biomedical Devices

    • Artificial heart (total artificial heart — SynCardia TAH); ventricular assist devices (VAD)
    • Cochlear implant — electric stimulation of auditory nerve for hearing restoration
    • 3D-printed organs (bioprinting using living cells — research stage for kidney, liver); artificial kidney (dialysis machine)

  12. Microbes and Human Welfare

    • Lactobacillus (curd/yogurt); E. coli (model organism; recombinant insulin production); Rhizobium (nitrogen fixation in legumes)
    • Penicillium notatum (penicillin antibiotic); Aspergillus niger (citric acid, vinegar)
    • Viruses used beneficially in gene therapy as adenoviral vectors

  13. Human Genome

    • Contains ~3.2 billion base pairs encoding ~20,000–25,000 genes
    • Human Genome Project (HGP) — completed April 2003 (13-year, $3 billion; USA/UK/France/Germany/Japan/China); applications: disease gene identification, personalised medicine, pharmacogenomics
    • India's Genome India Initiative (launched 2019) — sequencing 10,000 Indian genomes for population-specific disease research