AQA Biology Paper 2 Revision Notes

Key Topics

• Homeostasis and Response
• Inheritance, Variation, and Evolution
• Ecology

These notes cover topics 5 to 7 and are suitable for students taking higher and foundation tiers in double combined trilogy and triple or separate biology.

Homeostasis

• Definition: Regulation of internal conditions to maintain optimum conditions for enzyme action and cell functions.
• Regulated Conditions: Blood glucose concentration, temperature, and water levels.
• Nervous System:
  • Central Nervous System (CNS): Brain and spinal cord.
  • Peripheral Nervous System (PNS): Nerves throughout the body.
  • Reflex Arc: Involves sensory, relay, and motor neurons, bypassing the brain for faster response.
• Hormones and Glands:
  • Pituitary gland: Master gland controlling other glands.
  • Pancreas: Regulates blood glucose levels through insulin and glucagon.
  • Adrenal glands: Produce adrenaline.

Eye and Thermoregulation

• Eye Structure:
  • Accommodation: Adjusting lens shape to focus light.
  • Pupil: Adjusts to light intensity.
  • Myopia and Hyperopia: Shortsightedness and longsightedness.
  • Treatments: Glasses, contact lenses, laser eye surgery.
• Thermoregulation:
  • Controlled by brain signals.
  • Heat loss mechanisms: Sweating, vasodilation.
  • Heat retention mechanisms: Vasoconstriction, shivering.

Endocrine System

• Hormones:
  • Insulin and glucagon for blood glucose control.
  • Adrenaline for fight or flight response.
  • Thyroxin for metabolic rate.
• Diabetes:
  • Type 1: Lack of insulin production.
  • Type 2: Cells resistant to insulin.

Reproduction

• Menstruation Cycle:
  • FSH, LH, estrogen, and progesterone roles.
  • Contraception methods: Pills, injections, implants, barriers.
• Infertility Treatments:
  • IVF: In vitro fertilization.
  • Hormone injections for egg release.

Inheritance and Evolution

• Genetic Basics:
  • DNA structure and gene function.
  • Human Genome Project: Mapping out genes.
  • Genotype vs. Phenotype.
  • Dominant and recessive alleles explained.
  • Punnett squares for genetic probability.
• Variation and Evolution:
  • Natural selection: Darwin's theory.
  • Epigenetics: Gene expression influenced by environment.

Ecology

• Ecosystems:
  • Biotic and abiotic factors.
  • Food chains and energy flow.
  • Trophic levels and biomass pyramids.
  • Decomposition and carbon cycle.

Human Impact and Conservation

• Biodiversity:
  • Importance and threats due to human impact.
  • Conservation efforts.
• Sustainable Practices:
  • Fishing regulations.
  • Agricultural techniques to maintain food security.

Additional Points for Triple Biology

• Detailed kidney function and water/nitrogen balance.
• Plant hormones and their effects (e.g., gibberellins, auxins).

These notes aim to provide a comprehensive overview of the topics covered in AQA Biology Paper 2, focusing on the most important concepts and details needed for revision.