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Secondary 1 Science Semestral Assessment 2 (End of Year) Paper 1
Free Sec 1 Science SA2 Paper 1, Exam version, with questions, answers, and syllabus-aligned practice for Singapore students.
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Answers
TuitionGoWhere Practice Paper - Science Secondary 1 (Answer Key)
Section A: Multiple Choice and Short Answer Questions [25 marks]
1. A [1] Chemical energy in battery → electrical energy → kinetic energy in motor
2. [Depends on diagram - correct ray should show angle of incidence = angle of reflection] [1]
3. B [1] Iron is magnetic, sulfur is not - magnetic separation is most suitable
4. B [1] Total magnification = 15 × 20 = 300×
5. C [1] Elements contain only one type of atom
6. Gravitational potential energy → Kinetic energy [1] Accept: GPE → KE
7. 1. Wear protective gloves / Use eye protection [1] 2. Use in well-ventilated area / Avoid contact with skin [1] Accept any two reasonable precautions for corrosive chemicals
8. Work done = Force × Distance [1] Accept: Force × Displacement
9. Diffusion [1]
10. If the temperature increases, then the sugar will dissolve faster [2] 1 mark for if-then format, 1 mark for correct relationship Accept equivalent testable hypotheses
11.(a) Microvilli [1] Accept: Villi
11.(b) Microvilli increase the surface area [1] This allows more absorption of nutrients [1]
12. Classification: Mixture [1] Reason: The salt and water can be separated by physical means / The components retain their individual properties [1]
13.(a) A: Solid B: Liquid C: Gas [3] 1 mark each
13.(b) The particles gain kinetic energy and move faster [1] The particles move further apart and the regular arrangement breaks down [1]
Section B: Structured Questions [45 marks]
14.(a) Temperature and size of sugar pieces (surface area) [2] 1 mark each for identifying both independent variables
14.(b) Time to dissolve [1]
14.(c) Crushed sugar dissolves faster than sugar cubes [1] This shows that smaller pieces (larger surface area) dissolve faster [1]
14.(d) Crushed sugar has a larger surface area than sugar cubes [1] More sugar particles are exposed to the water [1] This increases the contact between sugar and water, making dissolving faster [1]
14.(e) Keep all other variables the same (temperature, size of sugar pieces) [1] Add stirring to one setup and no stirring to another, then compare dissolving times [1]
15.(a) Moment = Force × Distance = 500 × 0.2 = 100 N⋅m [2] 1 mark for method, 1 mark for correct answer
15.(b) For balance: Clockwise moment = Anticlockwise moment [1] 100 = Effort × 1.0 [1] Effort force = 100 N [1]
15.(c) Reduces the effort force needed / Makes lifting easier / Provides mechanical advantage [1]
15.(d) Work done = Force × Distance = 500 × 0.1 = 50 J [2] 1 mark for method, 1 mark for correct answer
16.(a) Ink: C [1] Explanation: It shows only one spot/color, indicating only one dye [1]
16.(b) Inks: A and D [1] Evidence: Both show a blue spot at the same height on the chromatogram [1]
16.(c) Different solvents have different polarities [1] This would cause the dyes to travel different distances [1] The separation pattern would change / Some dyes might separate better [1]
16.(d) Quick test / Requires small sample / Can identify multiple components / Sensitive [1]
17.(a) Both have a nucleus / Both have a nuclear membrane [1]
17.(b) Organism Q has a flagellum [1] The flagellum enables movement by beating/rotating to propel the organism [1]
17.(c) Convert units: 20 mm = 20,000 μm [1] Magnification = Image size ÷ Actual size = 20,000 ÷ 50 [1] Magnification = 400× [1]
17.(d) To find food / To escape from predators / To find suitable environment [1]
18.(a) As acid concentration increases, the reaction rate increases [1] Higher concentration produces gas faster / steeper initial slope [1]
18.(b) Higher concentration means more acid particles per unit volume [1] More frequent collisions between acid and magnesium [1] This increases the rate of reaction [1]
18.(c) The same amount of magnesium is used in all experiments [1] All the magnesium reacts completely, producing the same amount of gas [1]
18.(d) Prediction: The reaction rate would increase [1] Explanation: Higher temperature gives particles more kinetic energy [1] Particles move faster and collide more frequently [1] More collisions have enough energy to react [1]
Total: 70 marks
Marking Scheme Notes
Grade Boundaries (Suggested):
- A: 63-70 marks (90-100%)
- B: 56-62 marks (80-89%)
- C: 49-55 marks (70-79%)
- D: 42-48 marks (60-69%)
- E: 35-41 marks (50-59%)
- F: Below 35 marks (<50%)
General Marking Guidelines:
- Award marks for correct scientific terminology
- Accept equivalent expressions where meaning is clear
- For calculations, award method marks even if final answer is incorrect due to earlier error
- Spelling should be reasonably accurate for scientific terms
- Units are required for final answers in calculations
- Show working clearly for full marks in calculation questions