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S3 Integrated Science Practice Paper: Forces, Acids, Cells, Circuits and Energy (100 marks)
Science – S3 Practice
S3 integrated science paper: 6 questions, 24 parts, 100 marks in 60 minutes. Covers forces, acids, cells, circuits and energy, with full answers and marking points.
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Paper details
Section A: Forces and Motion (18 marks)
Answer all parts and show your working with units.
| # | Question | Answer and marking notes |
|---|---|---|
| 1 | A car accelerates from rest to 20 m/s in 5 seconds. Find the average acceleration. | Answer: 4 m/s^2 (a = (20 – 0) / 5 = 4) |
| 2 | How far does the car travel during these 5 seconds? | Answer: 50 m (s = 0.5 x (0 + 20) x 5 = 50) |
| 3 | A net force of 12 N acts on a 2 kg object. Find the acceleration. | Answer: 6 m/s^2 (a = F / m = 12 / 2 = 6) |
| 4 | A student has a weight of 45 N. Taking g = 10 N/kg, find the mass. | Answer: 4.5 kg (m = W / g = 45 / 10 = 4.5) |
Section B: Acids, Alkalis and Neutralisation (16 marks)
In questions 1 and 2 assume a strong acid at 25 degC.
| # | Question | Answer and marking notes |
|---|---|---|
| 5 | A solution has a hydrogen ion concentration of 1 x 10^-3 mol/dm^3. Find its pH. | Answer: 3 (pH = -log(10^-3) = 3) |
| 6 | The solution is diluted 10 times. What is the new pH? | Answer: 4 (concentration becomes 10^-4, so pH rises by 1) |
| 7 | What volume of 0.2 M hydrochloric acid neutralises 25 cm^3 of 0.1 M sodium hydroxide? | Answer: 12.5 cm^3 (moles = 25 x 0.1 = 2.5 mmol, volume = 2.5 / 0.2 = 12.5) |
| 8 | What colours does methyl orange show in acidic and in neutral solutions? | Answer: red in acid and yellow in neutral (change interval pH 3.1 to 4.4) |
Section C: Cells and Inheritance (16 marks)
A genetic diagram is required in question 4.
| # | Question | Answer and marking notes |
|---|---|---|
| 9 | How many chromosomes are in a human body cell, and how many in a gamete? | Answer: 46 in a body cell and 23 in a gamete (the number is halved) |
| 10 | After mitosis, how many daughter cells come from one body cell, and how many chromosomes does each have? | Answer: 2 daughter cells, each with 46 chromosomes (the number is unchanged) |
| 11 | How many sperm cells are produced from one spermatogonium by meiosis? | Answer: 4 (each with 23 chromosomes) |
| 12 | Two individuals with genotype Aa are crossed. What is the ratio of dominant to recessive offspring? | Answer: 3 to 1 (AA, Aa and Aa are dominant, aa is recessive) |
Section D: Simple Circuits (18 marks)
Assume the resistance of the battery and wires is negligible.
| # | Question | Answer and marking notes |
|---|---|---|
| 13 | A 6 V battery is connected to a 3 ohm resistor. Find the current. | Answer: 2 A (I = V / R = 6 / 3 = 2) |
| 14 | Two 3 ohm resistors are connected in series. Find the total resistance. | Answer: 6 ohm (R = 3 + 3 = 6) |
| 15 | Two 3 ohm resistors are connected in parallel. Find the total resistance. | Answer: 1.5 ohm (1/R = 1/3 + 1/3 = 2/3, so R = 1.5) |
| 16 | In the circuit above, with a 6 V battery and a current of 2 A, find the power. | Answer: 12 W (P = V x I = 6 x 2 = 12) |
Section E: Separating Mixtures (16 marks)
Answer each part in one or two sentences and name the method.
| # | Question | Answer and marking notes |
|---|---|---|
| 17 | Which method can recover salt dissolved in water? Briefly explain the principle. | Answer: distillation or crystallisation; distillation uses the difference in boiling points and crystallisation uses the change of solubility with temperature |
| 18 | Which method separates sand from water? | Answer: filtration (sand is an insoluble solid trapped by the filter paper) |
| 19 | What is the main difference between distillation and fractional distillation? | Answer: distillation separates one volatile liquid from non-volatile impurities; fractional distillation separates liquids with close boiling points using a fractionating column |
| 20 | Which method separates a mixture of pigments? | Answer: paper chromatography (pigments travel at different rates in the solvent) |
Section F: Energy and Energy Transfer (16 marks)
In question 1 take the specific heat capacity of water as 4200 J/(kg degC).
| # | Question | Answer and marking notes |
|---|---|---|
| 21 | How much energy is needed to heat 200 g of water from 20 to 60 degC? | Answer: 33600 J (E = mc delta T = 0.2 x 4200 x 40) |
| 22 | In a food chain the producers contain 10000 kJ. With about 10 percent transfer efficiency, how much energy reaches the secondary consumer? | Answer: 100 kJ (10000 to 1000 in the primary consumer to 100 in the secondary consumer) |
| 23 | Which form of energy is converted into chemical energy in photosynthesis? | Answer: light energy is converted into chemical energy stored in glucose |
| 24 | Give one fossil fuel and one renewable energy source, and state one advantage of the renewable source. | Answer: coal is a fossil fuel and solar energy is renewable; solar power releases no carbon dioxide when generating electricity |
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