BRAINCAKE

OCR GCSE Combined Science

OCR Combined Science A (J250)18 topics334 lessons

OCR GCSE Combined Science revision for OCR Combined Science A (J250): 18 topics and 334 short lessons, each with R.E.C.I.P.E. recall steps and a quiz. The topics follow the OCR specification.

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1. Cell level systems

19 lessons

  1. Light microscopes and staining
  2. Sub-cellular structures and their functions
  3. Electron microscopy
  4. DNA as a polymer
  5. The double helix structure of DNA
  6. Investigating enzyme-controlled reactions
  7. How enzymes work
  8. Cellular respiration supplies ATP
  9. Respiration is exothermic
  10. Aerobic and anaerobic respiration
  11. Sugars and carbohydrates
  12. Amino acids and proteins
  13. Fatty acids, glycerol and lipids
  14. Photosynthetic organisms as producers
  15. The process of photosynthesis
  16. Photosynthesis as an endothermic reaction
  17. Investigating photosynthesis
  18. Factors affecting the rate of photosynthesis
  19. Limiting factors and graphs

2. Scaling up

16 lessons

  1. Transport into and out of cells
  2. Mitosis and the cell cycle
  3. Why cells differentiate
  4. Where stem cells are found
  5. Functions of stem cells
  6. Embryonic and adult stem cells
  7. Exchange surfaces and transport systems: surface area to volume ratio
  8. Substances transported into and out of organisms
  9. The human circulatory system
  10. Adaptations of the heart and blood vessels
  11. Red blood cells and plasma
  12. Uptake of water and mineral ions by plants
  13. Transpiration, translocation and stomata
  14. Xylem and phloem structure
  15. Environmental factors and water uptake
  16. Using a potometer

3. Organism level systems

13 lessons

  1. Structure of the nervous system
  2. How the nervous system coordinates a response
  3. The reflex arc
  4. Hormonal coordination and the endocrine system
  5. Thyroxine and adrenaline
  6. Hormones in human reproduction
  7. Control of the menstrual cycle
  8. Hormones and contraception
  9. Hormones and infertility treatment
  10. Maintaining a constant internal environment
  11. How insulin controls blood sugar level
  12. How glucagon and insulin work together
  13. Type 1 and type 2 diabetes

4. Community level systems

6 lessons

  1. Cycling of materials in an ecosystem
  2. Microorganisms and decomposition
  3. The carbon cycle and the water cycle
  4. Levels of organisation in an ecosystem
  5. Abiotic and biotic factors affecting communities
  6. Interdependence and competition

5. Genes, inheritance and selection

15 lessons

  1. Key genetics terms
  2. The genome
  3. Genome, environment and phenotype
  4. Mutations and variants
  5. Haploid and diploid
  6. Meiosis and gametes
  7. Single gene inheritance
  8. Predicting single gene crosses
  9. Sex determination in humans
  10. Features controlled by many genes
  11. Genetic variation within a population
  12. Classification and developments in biology
  13. Natural selection and mutation
  14. Evolution and the formation of new species
  15. Evidence for evolution

6. Global challenges

25 lessons

  1. Sampling organisms in a habitat
  2. Human interactions and biodiversity
  3. Benefits and challenges of conservation
  4. Selective breeding of food plants and animals
  5. Genetic engineering
  6. Steps in genetic engineering
  7. Benefits and risks of gene technology in agriculture
  8. Describe the relationship between health and disease
  9. Describe different types of diseases communicable and non-communicable diseases
  10. Describe the interactions between different types of disease HIV and tuberculosis, and HPV and cervical cancer
  11. Explain how communicable diseases (caused by viruses, bacteria, protists and fungi) are spread in animals and plants
  12. Explain how the spread of communicable diseases may be reduced or prevented in animals and plants
  13. Describe a minimum of one common human infection, one plant disease and sexually transmitted infections in humans including HIV/AIDS
  14. White blood cells and platelets in defence
  15. Non-specific defences against pathogens
  16. The immune system and disease
  17. Vaccines and medicines
  18. Discovery and development of new medicines
  19. Non-communicable diseases and their causes
  20. Treatments for cardiovascular disease
  21. Lifestyle factors and non-communicable diseases
  22. Cancer and uncontrolled cell division
  23. Stem cells in medicine
  24. Gene technology in medicine
  25. The human genome and medicine

7. Particles

8 lessons

  1. The particle model and changes of state
  2. Physical and chemical changes
  3. Limitations of the particle model
  4. How the atomic model has changed
  5. The nuclear model of the atom
  6. The size of atoms and small molecules
  7. Relative charge and mass of subatomic particles
  8. Protons, neutrons and electrons in atoms and ions

8. Elements, compounds and mixtures

26 lessons

  1. Purity of a substance
  2. Melting point and purity
  3. Relative formula mass
  4. Empirical formulae
  5. Formulations and alloys
  6. Separating mixtures
  7. Paper and thin layer chromatography
  8. Stationary and mobile phases in chromatography
  9. Interpreting chromatograms and calculating Rf values
  10. Choosing a suitable purification technique
  11. Using chromatography to tell pure from impure substances
  12. Metals and non-metals: physical and chemical properties
  13. Atomic structure and the position of metals and non-metals
  14. Electron arrangement, group, period and atomic number
  15. Bonding in ionic compounds, simple molecules and giant covalent structures
  16. Bonding: electrostatic forces and transfer or sharing of electrons
  17. Dot and cross diagrams for covalent and ionic substances
  18. Limitations of bonding models and diagrams
  19. Electron arrangement and the reactions of elements
  20. From Mendeleev's table to the modern Periodic Table
  21. Carbon forms four covalent bonds
  22. Carbon chains, rings and families of compounds
  23. Diamond, graphite, fullerenes and graphene
  24. Energy, bonds and changes of state
  25. Predicting states from data
  26. Bonding and bulk properties of materials

9. Chemical reactions

34 lessons

  1. Writing formulae of elements and simple compounds
  2. Conservation of mass and balanced equations
  3. Using the Periodic Table to write formulae and equations
  4. Deducing formulae from common ions
  5. Balanced ionic equations
  6. State symbols
  7. Tests for oxygen, hydrogen, carbon dioxide and chlorine
  8. The Avogadro constant and the mole
  9. Mass and amount in moles
  10. Concentration of solutions
  11. The law of conservation of mass
  12. Changes in mass in open systems
  13. Stoichiometry and limiting reactants
  14. Calculating reacting masses from equations
  15. Exothermic and endothermic reactions
  16. Reaction profiles
  17. Activation energy
  18. Calculating energy changes from bond energies
  19. Oxidation and reduction as gain or loss of oxygen
  20. Oxidation and reduction as loss or gain of electrons
  21. Hydrogen ions and hydroxide ions in acids and alkalis
  22. Neutralisation: acid and alkali or base forming a salt and water
  23. The ionic equation for aqueous neutralisation
  24. Reactions of acids with carbonates and metals
  25. Dilute, concentrated, weak and strong acids
  26. Measuring acidity and alkalinity with pH
  27. Hydrogen ions and the pH value
  28. How pH changes with hydrogen ion concentration
  29. Measuring pH: universal indicator and pH meters
  30. Products at the electrodes in electrolysis
  31. Electrolysis of molten binary ionic compounds
  32. Electrolysis of aqueous solutions
  33. Half equations at the electrodes
  34. Inert and non-inert electrodes

10. Predicting and identifying reactions

5 lessons

  1. Properties of Groups 1, 7 and 0
  2. Outer electrons and trends in Groups 1, 7 and 0
  3. Predicting reactions from the Periodic Table
  4. Reactivity of metals with water and acids
  5. Order of reactivity of metals

11. Monitoring and controlling chemical reactions

12 lessons

  1. Practical methods for finding the rate of a reaction
  2. Interpreting rate of reaction graphs
  3. Factors that change the rate of reaction
  4. Collision theory: temperature, concentration and pressure
  5. Surface area to volume ratio and rate
  6. Characteristics of catalysts
  7. Identifying catalysts
  8. Catalysts and activation energy
  9. Enzymes as catalysts
  10. Reversible reactions
  11. Dynamic equilibrium
  12. Changing the position of equilibrium

12. Global challenges

20 lessons

  1. Extracting metals using carbon
  2. Extracting metals by electrolysis
  3. Bacterial and phytoextraction of metals
  4. Life-cycle assessment
  5. Interpreting life-cycle assessment data
  6. Recycling a material for a different use
  7. Recycling decisions
  8. Fractional distillation of crude oil
  9. Why fractions separate
  10. Alkanes in the fractions
  11. Crude oil as a source of hydrocarbons
  12. Dependence on hydrocarbons
  13. Cracking hydrocarbons
  14. Evidence for the early atmosphere
  15. How an oxygen-rich atmosphere developed
  16. The greenhouse effect
  17. Human causes of climate change
  18. Effects of greenhouse gases and how to reduce them
  19. Air pollutants and their problems
  20. Making potable water

13. Matter

14 lessons

  1. Development of the atomic model
  2. The structure of the atom
  3. The size of atoms and small molecules
  4. Defining density
  5. Density and the states of matter
  6. Density when mass is conserved
  7. Conservation of mass in changes of state
  8. Physical and chemical changes
  9. Heating and internal energy
  10. Specific heat capacity and specific latent heat
  11. Calculating energy for a temperature change
  12. Calculating energy for a change of state
  13. Gas molecules, temperature and pressure
  14. Temperature and pressure of a gas at constant volume

14. Forces

33 lessons

  1. Measuring distance and time
  2. Calculating speed from distance-time graphs
  3. Converting units and calculating rates
  4. Vectors and scalars: displacement and velocity
  5. Interpreting motion graphs
  6. Area under a velocity-time graph
  7. Average speed for non-uniform motion
  8. Distance, time and speed: uniform motion and uniform acceleration
  9. Ways objects interact
  10. Interaction pairs of forces
  11. Forces as vectors and free body diagrams
  12. Newton's first law
  13. Vector diagrams, resultants and equilibrium
  14. Forces on a falling object and terminal velocity
  15. Resultant forces and free body diagrams
  16. Balanced forces and a zero resultant
  17. Newton's Second Law: F = ma
  18. Inertia and inertial mass
  19. Momentum and conservation of momentum
  20. Work done, force and distance
  21. Stored energy and energy transfers
  22. Power as the rate of energy transfer
  23. Newton's Third Law: equilibrium and non-equilibrium
  24. Circular motion and changing velocity
  25. Forces needed to stretch, bend or compress
  26. Elastic and plastic deformation
  27. Force and extension for a spring
  28. Linear and non-linear force-extension
  29. Calculating the spring constant
  30. Work done in stretching a spring
  31. Gravitational fields and attraction
  32. Weight and gravitational field strength
  33. Acceleration in free fall

15. Electricity and magnetism

30 lessons

  1. Charge and matter
  2. Producing static electricity
  3. Electron transfer and static
  4. Current and the flow of charge
  5. Current in a closed loop
  6. Charge, current and time
  7. Series and parallel circuits
  8. Circuit symbols and d.c. conventions
  9. Current, potential difference and resistance
  10. The relationship between I, R and V
  11. Why resistance can change
  12. Circuits to investigate resistance
  13. Using graphs to show linear and non-linear circuit elements
  14. Relating I-V curves to the properties of circuit elements
  15. Why resistors in series and in parallel change the net resistance
  16. Calculating currents, potential differences and resistances in series and parallel circuits
  17. Designing and using d.c. circuits for measurement and testing
  18. Power, potential difference, current and energy transfer
  19. Circuit calculations with resistors in series
  20. Attraction and repulsion between magnetic poles
  21. Permanent and induced magnets
  22. Magnetic fields around a magnet
  23. The Earth's magnetic field and a dipping compass
  24. Magnetic field around a current-carrying wire
  25. Strength of the field around a wire
  26. Solenoids and electromagnets
  27. Force on a current-carrying wire
  28. Fleming's left-hand rule
  29. Force on a conductor: F = BIL
  30. Electric motors

16. Waves and radioactivity

31 lessons

  1. Wave motion: amplitude, wavelength, frequency and period
  2. Defining wavelength and frequency
  3. The wave speed equation
  4. Calculations with wave speed, frequency and wavelength
  5. Transverse and longitudinal waves
  6. Ripples, sound waves and measuring wave speed
  7. Evidence that the wave travels, not the medium
  8. Electromagnetic waves are transverse and travel at the same speed in space
  9. Electromagnetic waves transfer energy from a source to an absorber
  10. Frequency and wavelength across the electromagnetic spectrum
  11. The groupings of the electromagnetic spectrum
  12. What our eyes can detect
  13. Light is an electromagnetic wave
  14. Uses of electromagnetic waves
  15. Hazards of ultraviolet, X-rays and gamma rays
  16. Radio waves and electrical circuits
  17. Absorption, transmission, reflection and refraction
  18. Wave velocity in different substances and refraction
  19. Atomic nuclei: protons and neutrons
  20. Isotopes and neutron number
  21. Nuclear notation and isotopes
  22. Unstable nuclei and types of radiation
  23. Changes to the nucleus on emission
  24. Balanced equations for radioactive decay
  25. Balancing equations for alpha, beta and gamma emission
  26. Electron energy levels, excitation and ionisation
  27. Radiation from atoms and nuclei
  28. Half-life and random decay
  29. Half-life calculations and decay graphs
  30. Penetrating power of alpha, beta and gamma
  31. Contamination and irradiation

17. Energy

12 lessons

  1. Conservation of energy in a closed system
  2. Energy store changes in common situations
  3. Energy changes: heating, work done by forces and by current
  4. Calculating energy changes on a common scale
  5. Kinetic, gravitational potential and elastic energy
  6. Energy dissipation
  7. Energy transfers in domestic devices
  8. Power ratings of appliances
  9. Calculating energy efficiency
  10. Increasing efficiency
  11. Lubrication and thermal insulation
  12. Rate of cooling and wall thickness

18. Global challenges

15 lessons

  1. Typical speeds in everyday life
  2. Estimating everyday accelerations
  3. Converting units and calculating rates
  4. Measuring human reaction times
  5. Stopping distances and road safety
  6. Dangers of large decelerations
  7. Energy sources on Earth
  8. Trends in energy resource use
  9. The national grid and voltage
  10. Step-up and step-down transformers
  11. Why the national grid is efficient
  12. UK mains supply
  13. Direct and alternating voltage
  14. Live, neutral and earth wires
  15. Mains safety and the live wire