AQA Biology Paper 2 Topics: 5 to 7

Overview

• This lecture covers key biology topics for AQA Biology Paper 2, suitable for both higher and foundation tiers, including combined trilogy and separate biology.
• Topics include Homeostasis and Response, Inheritance, Variation and Evolution, and Ecology.
• Some content is specific to triple science students.

Topic 5: Homeostasis and Response

Homeostasis

• Homeostasis: Regulation of internal conditions to maintain stable conditions for enzyme reactions.
• Body regulates:
  • Blood glucose concentration
  • Temperature
  • Water levels

Nervous System

• Central Nervous System (CNS): Brain and spinal cord
• Peripheral Nervous System (PNS): Nerve network
• Process of signal transmission:
  • Receptor detects stimulus (e.g., skin detecting heat)
  • Signal travels via sensory neurons
  • Synapse: Gap where neurotransmitters transmit the signal
  • Signal processed by brain or directly to effector (reflex)
• Reflex Arc: Faster pathway bypassing the brain

Hormones and Glands

• Glands produce chemicals/hormones (e.g., salivary glands, pancreas)
• Reaction time experiments: Use a ruler drop test to assess effects of variables like caffeine.

Brain Functions (Triple Content)

• Cerebral Cortex: Memory, speech, problem-solving
• Cerebellum: Motor skills, balance, coordination
• Medulla Oblongata: Heart and breathing rate, adrenaline release
• MRI scans for brain activity

Eye Structure and Function

• Accommodation: Focus light through lens adjustment
  • Distant objects: Ciliary muscles relax, lens thins
  • Near objects: Ciliary muscles contract, lens thickens
• Pupil size adapts based on light intensity
• Myopia and Hyperopia: Corrected with glasses/contact lenses

Thermoregulation

• Regulation of body temperature through vasodilation, vasoconstriction, and shivering

Endocrine System

• Gland hormone secretion via blood (slower than nervous system)
• Pituitary Gland: Master gland influencing others
• Pancreas: Insulin (lower blood glucose) and glucagon (raise blood glucose)
• Diabetes types:
  • Type 1: Lack of insulin production
  • Type 2: Insulin resistance

Water and Nitrogen Balance (Triple Content)

• Kidneys: Balance water and filter blood
  • ADH: Regulates water reabsorption
  • Dialysis: Artificial blood filtration

Reproduction

• Menstruation: Involving FSH, estrogen, LH, and progesterone
• Contraception: Various methods to prevent fertilization
• IVF: Assists with infertility

Topic 6: Inheritance, Variation, and Evolution

Genetic Concepts

• Meiosis: Produces genetic variation in gametes
• DNA and Genes: Genome comprises all genetic material; genes code for proteins
• Monomers of DNA: Nucleotides (A, T, C, G)
• Mutations: Can lead to non-functional proteins

Inheritance Patterns

• Dominant and recessive alleles
• Use of Punnett squares to predict genotype probabilities

Evolutionary Theory

• Natural selection: Darwin’s theory of survival of the fittest
• Epigenetics: Environmental factors influencing gene expression
• Antibiotic resistance as an example of evolution

Genetic Engineering

• Modification for traits like insulin production
• Gene Splicing: Inserting genes for desired traits

Topic 7: Ecology

Ecosystem Dynamics

• Abiotic Factors: Non-living environmental factors (light, temperature)
• Biotic Factors: Living organism interactions (predators, prey)
• Food Chains and Trophic Levels
  • Producers, primary, secondary, tertiary consumers
  • Apex predators

Conservation and Sustainability

• Biodiversity ensures ecosystem stability
• Human impacts: Pollution, deforestation, habitat destruction
• Sustainable practices: Fishing quotas, reducing waste

Conclusion

• Emphasis on understanding these key biology topics to prepare effectively for exams.
• Recommendations to practice and study further using resources like playlists for additional papers.