BIOLOGY – SHORT NOTES

1. Cell: Structure & Function

• Cell → Basic unit of life

• Prokaryotic cells → No nucleus (bacteria)

• Eukaryotic cells → True nucleus (plants, animals)

Cell Organelles

• Nucleus → Control center

• Mitochondria → Powerhouse, ATP production

• Ribosomes → Protein synthesis

• Golgi body → Packaging and transport

• Lysosomes → Waste removal

• Chloroplast → Photosynthesis (plants)

2. Cell Division

Mitosis

• Produces 2 identical cells

• Growth & repair

Meiosis

• Produces 4 gametes

• Sexual reproduction

3. Plant Physiology

Photosynthesis

• Equation:
  CO₂ + H₂O → Glucose + O₂

• Occurs in chloroplast

• Light + Chlorophyll required

Transpiration

• Loss of water through stomata

• Helps in cooling & nutrient movement

4. Human Physiology

Digestive System

• Mouth → Starch digestion begins

• Stomach → Proteins digestion

• Small intestine → Main digestion + absorption

Respiratory System

• Exchange of gases in alveoli

• Hemoglobin carries oxygen

Circulatory System

• Heart has 4 chambers

• RBC → Oxygen transport

• WBC → Fight infection

• Platelets → Clotting

Excretory System

• Kidney → Filters blood

• Nephron → Functional unit

5. Genetics

• DNA → Genetic material

• Gene → Unit of heredity

• Chromosomes → DNA + proteins

• Mendel’s laws:

  • Dominance

  • Segregation

  • Independent assortment

6. Reproduction

Asexual Reproduction

• Binary fission, budding, fragmentation

Sexual Reproduction

• Gametes fuse to form zygote

7. Evolution

• Darwin: Natural selection

• Evolution = Change over generations

8. Ecology

• Food chain → Producer → Consumer → Decomposer

• Ecosystem → Biotic + Abiotic

• Pollution → Air, water, soil

9. Microorganisms

• Bacteria → Helpful & harmful

• Viruses → Need host to reproduce

• Fungi → Decomposers

10. Plant & Animal Tissues

• Plant tissues → Meristematic, permanent

• Animal tissues → Epithelial, connective, muscular, nervous