Comprehensive Biology Notes
Cell Biology
- The cell is the structural and functional unit of life.
- Prokaryotic cells lack a nucleus and membrane-bound organelles.
- Eukaryotic cells contain a nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, and
lysosomes.
- Mitochondria are the powerhouse of the cell, producing ATP through cellular respiration.
Genetics
- DNA is a double helix composed of nucleotides (A, T, C, G).
- Mendel’s Laws of Inheritance: Law of Segregation, Law of Independent Assortment, and Law of
Dominance.
- RNA differs from DNA: single-stranded, contains uracil instead of thymine.
- Central Dogma: DNA → RNA → Protein.
Human Physiology
- Digestive system: Mouth → Esophagus → Stomach → Small intestine → Large intestine.
- Respiratory system: Exchange of gases occurs in alveoli of lungs.
- Circulatory system: Heart pumps blood through arteries, veins, and capillaries.
- Nervous system: Brain and spinal cord coordinate body functions; neurons transmit signals.
Plant Physiology
- Photosynthesis occurs in chloroplasts: 6CO■ + 6H■O → C■H■■O■ + 6O■.
- Transpiration: Loss of water vapor mainly through stomata.
- Transport: Xylem conducts water and minerals; Phloem transports food.
- Plant hormones: Auxins, Gibberellins, Cytokinins, Ethylene, and Abscisic acid.
Ecology
- Ecosystem: Interaction of living (biotic) and non-living (abiotic) components.
- Food chain: Sequence of organisms through which energy flows.
- Pyramid of energy is always upright.
- Biodiversity hotspots in India: Himalaya, Indo-Burma, Indo-Malayan region.
Evolution
- Charles Darwin proposed the Theory of Natural Selection.
- Lamarck proposed the Theory of Inheritance of Acquired Characteristics.
- Fossil records, comparative anatomy, and molecular biology provide evidence of evolution.
- Speciation occurs when populations become reproductively isolated.
Human Reproduction
- Male reproductive system: Testes, vas deferens, seminal vesicles, prostate gland, penis.
- Female reproductive system: Ovaries, fallopian tubes, uterus, cervix, vagina.
- Fertilization usually occurs in the fallopian tube.
- Gestation period in humans: ~9 months.
Biotechnology
- Genetic engineering involves manipulation of DNA using restriction enzymes and ligases.
- Recombinant DNA technology allows insertion of foreign genes into host organisms.
- Polymerase Chain Reaction (PCR) amplifies DNA.
- Applications: Medicine (insulin production), agriculture (GM crops), industry (enzymes).
