All-in-One Biology Overview

This guide is based on a comprehensive lecture on GCSE biology, specifically tailored for the Edexcel specification. It covers various key topics, definitions, and processes in biology, which are essential for students preparing for exams.

Biology Basics

• Cell Types:

  • Animal cells resemble a fried egg with a nucleus (control center), cytoplasm (site of chemical reactions), cell membrane (controls entry/exit of substances), mitochondria (energy supply via aerobic respiration), and ribosomes (protein synthesis).
  • Plant cells have similar structures but include a cell wall (support), vacuole (cell sap storage), and chloroplasts (site of photosynthesis).

• Bacteria:

  • Features include a cell wall, sometimes a flagella for movement, and plasmids (important for genetic engineering).

Specialized Cells

• Sperm Cells:

  • Tail for mobility, mitochondria for energy, enzymes in the acrosome for penetrating the egg.

• Egg Cells:

  • Contain a haploid nucleus, hardens membrane post-fertilization, nutrient-rich cytoplasm, and a protective jelly coat.

Plant and Human Anatomy

• Ciliated Cells: Found in oviducts and trachea, they move eggs or trap pathogens via cilia.

• Nervous System:

  • Includes brain (cerebral cortex, cerebellum, medulla) and spinal cord. Functions include processing information and controlling body functions.
  • Damage can lead to loss of function or paralysis (e.g., quadriplegia).

Microscopes

• Types:

  • Light microscopes: Up to 2000x magnification, use living samples.
  • Electron microscopes: Up to 2 million times magnification, require dead specimens.

• Magnification Calculations:

  • Formula: Image size = Magnification x Object size.

Enzymes and Reactions

• Enzyme Function: Biological catalysts speeding up reactions by lowering activation energy.
• Digestive Enzymes: Amylase (starch to glucose), Protease (protein to amino acids), Lipase (fats to fatty acids and glycerol).

Transport Systems

• Diffusion: Movement from high to low concentration.
• Osmosis: Movement of water across a membrane from high to low water potential.
• Active Transport: Movement against concentration gradient, requires energy.

Cell Cycle and Growth

• Mitosis: Produces two identical daughter cells for growth/repair.
• Meiosis: Produces four varied gametes, essential for sexual reproduction.

Genetics

• Definitions:
  • Gene: DNA segment coding for a protein.
  • Alleles: Variations of a gene.
  • Phenotype vs. Genotype: Physical traits vs. genetic makeup.
• Inheritance Patterns: Dominant/recessive traits, codominance, sex-linked traits like colorblindness.

Evolution and Natural Selection

• Evolutionary Theory: Describes how species arise from simple life forms.
• Natural Selection: Survival of the fittest due to advantageous mutations.

Genetic Engineering

• Applications: Producing human insulin via bacterial plasmids, GM crops for resistance.
• Selective Breeding: Enhances desired traits in plants/animals.

Health and Disease

• Types:

  • Communicable: Spread via pathogens.
  • Non-communicable: Lifestyle/genetic.

• Immune System:

  • White blood cells (phagocytes and lymphocytes) act against pathogens.
  • Vaccinations induce immune memory without causing disease.

Medical Applications

• Drug Development: Involves preclinical and clinical trials to ensure safety and efficacy.
• Monoclonal Antibodies: Used in diagnostics (e.g., pregnancy tests) and targeting diseases like cancer.

This guide compresses the key biological concepts into bite-sized notes for effective study and revision. Ensure you grasp each section thoroughly to prepare well for your exams.