Biology Revision Sheet

1. 📌 Essentials

• Biology: Study of life, interactions, and cellular structures.
• Characteristics of Life: Organization, metabolism, growth, reproduction, response.
• Cell Theory: All organisms are made of cells; cells arise from pre-existing cells.
• etic Material: DNA is the hereditary molecule, double helix structure.
• Metabolic Processes: Cellular respiration (energy release) and photosynthesis (energy capture).
• Levels of Organization: Cell → Tissue → Organ → Organ System → Organism.
• Taxonomy Hierarchy: Kingdom, Phylum, Class, Order, Family, Genus, Species.
• Macromolecules: Proteins, carbohydrates, lipids, nucleic acids.
• Cell Membrane: Lipid bilayer with embedded proteins; controls substance entry/exit.
• Cell Division: Mitosis for growth/repair; meiosis for reproduction and genetic diversity.
• Genetic Code: Transcription (DNA to mRNA), translation (mRNA to protein).
• Enzymes: Catalysts lowering activation energy; specific to substrates.
• ATP: Main energy currency, produced in mitochondria.
• Water: Cohesion, surface tension, essential for biological reactions.
• Genetic Inheritance: Mendel’s laws, dominant/recessive, Punnett squares.
• Genetic Technologies: PCR, cloning, gene editing.

2. 🧩 Key Structures & Components