1. What is the function of the mitochondria in a cell?

2. State the difference between a prokaryotic and a eukaryotic cell.

3. Name three specialised cells in the human body and state their functions.

4. What is osmosis?

5. Describe the role of enzymes in the digestive system.

6. What is the word equation for aerobic respiration?

7. Where in the human body does gas exchange occur?

8. How does the structure of a leaf help with photosynthesis?

9. What is the role of white blood cells?

10. Define pathogen.

11. Describe one way a vaccination protects the body.

12. What is meant by the term ‘non-communicable disease’? Give an example.

13. How do antibiotics work?

14. Explain natural selection using an example.

15. Name the four bases in DNA and how they pair.

16. What is a genotype and how does it differ from a phenotype?

17. What does a food chain show?

18. What is the atomic number of an element?

19. How many electrons are in the outer shell of a group 1 element?

20. Describe the structure of an atom.

21. What is the charge of a proton, neutron, and electron?

22. What is an isotope?

23. How do you separate a soluble solid from a liquid?

24. Write the word equation for the reaction between hydrochloric acid and sodium hydroxide.

25. What is the pH of a neutral solution?

26. What ions are present in acids and in alkalis?

27. What is the difference between an endothermic and exothermic reaction?

28. What is the general formula for alkanes?

29. Describe the process of fractional distillation of crude oil.

30. What is a polymer?

31. What are the main greenhouse gases?

32. Describe how carbon dioxide contributes to global warming.

33. What is a life cycle assessment (LCA) used for?

34. How does the reactivity of group 7 elements change down the group?

35. What is the equation for calculating speed?

36. Define the term ‘acceleration’.

37. State Newton's First Law of Motion.

38. What is the unit of force?

39. What does the gradient of a distance-time graph represent?

40. State the equation for kinetic energy.

41. What is the principle of conservation of energy?

42. Name three renewable energy resources.

43. What is the function of a fuse in a plug?

44. Define the terms current, voltage, and resistance.

45. What is the equation linking energy transferred, charge, and potential difference?

46. What happens to the resistance of a filament lamp as the temperature increases?

47. What is the speed of sound in air?

48. How are electromagnetic waves ordered in terms of increasing frequency?

49. What type of radiation is used in medical imaging?

50. What are the potential dangers of exposure to ionising radiation?

1. To release energy through aerobic respiration.

2. Prokaryotic cells (e.g. bacteria) do not have a nucleus; eukaryotic cells do.

3. Examples:

   • Red blood cell – carries oxygen

   • Nerve cell – transmits electrical impulses

   • Root hair cell – absorbs water and minerals

4. The movement of water across a partially permeable membrane from a dilute solution to a concentrated one.

5. They catalyse (speed up) the breakdown of large molecules into smaller soluble molecules.

6. Glucose + Oxygen → Carbon dioxide + Water (+ Energy)

7. In the alveoli of the lungs.

8. Large surface area, thin cells, chloroplasts for photosynthesis, stomata for gas exchange.

9. To defend the body against pathogens (e.g. by producing antibodies, engulfing pathogens).

10. A microorganism that causes disease.

11. Vaccinations stimulate white blood cells to produce antibodies and create memory cells.

12. A disease that cannot be passed from person to person. Example: coronary heart disease.

13. They kill or inhibit the growth of bacteria.

14. Organisms with beneficial adaptations survive and reproduce, passing on genes (e.g. giraffes with long necks).

15. A-T, C-G (Adenine pairs with Thymine, Cytosine with Guanine).

16. Genotype = genetic makeup; Phenotype = physical expression of the genes.

17. The transfer of energy (and matter) between organisms in an ecosystem.

⚗️ Chemistry (Answers 18–34)

18. The number of protons in the nucleus.

19. 1 electron.

20. A nucleus made of protons and neutrons, surrounded by electrons in shells.

21. Proton = +1, Neutron = 0, Electron = -1.

22. Atoms of the same element with different numbers of neutrons.

23. Evaporation (or crystallisation).

24. Hydrochloric acid + Sodium hydroxide → Sodium chloride + Water

25. pH 7.

26. Acids produce H⁺ ions; alkalis produce OH⁻ ions.

27. Endothermic = absorbs energy, Exothermic = releases energy.

28. CnH2n+2

29. Crude oil is heated and its vapours are separated based on boiling point.

30. A long-chain molecule made from repeating units called monomers.

31. Carbon dioxide, methane, and water vapour.

32. It traps heat in the Earth's atmosphere (greenhouse effect).

33. To assess the environmental impact of a product from production to disposal.

34. Reactivity decreases down the group (halogens become less reactive).

⚡ Physics (Answers 35–50)

35. Speed = Distance ÷ Time

36. The rate of change of velocity.

37. An object remains at rest or moves at constant velocity unless acted on by a resultant force.

38. Newton (N)

39. Speed.

40. Kinetic energy = ½ × mass × velocity²

41. Energy cannot be created or destroyed, only transferred or transformed.

42. Solar, wind, hydroelectric (others: tidal, geothermal, biomass).

43. To break the circuit if too much current flows (safety device).

44.  

• Current: flow of charge

• Voltage (potential difference): energy per unit charge

• Resistance: opposition to current flow

45. Energy transferred = Charge × Potential difference

46. Resistance increases.

47. Approximately 330 m/s (varies slightly with temperature).

48. Radio waves → Microwaves → Infrared → Visible light → Ultraviolet → X-rays → Gamma rays

49. X-rays and gamma rays.

50. Can damage DNA, cause mutations, cancer, or radiation sickness.