SOLUTIONS — SAMPLE PAPER 1
Section A
- b) Natural systems can be complex and models help simplify them.
- a) kilogram
- b) Useful when those details are not important for the question.
- b) An explanation supported by evidence and testing.
- a) mass
- c) Based on evidence and can be compared with observations.
- b) A quick check of whether a result is reasonable is needed.
- b) Studying a mobile phone using ideas from physics, chemistry and mathematics.
- a) A regular pattern observed in nature.
- c) Re-examine the assumptions, model or measurements.
Section B
11. A scientific model is a simplified representation of a real system used to understand or study a particular question. For example, a moving car can be represented as a point when studying its motion.
12. Standard units provide a common language for measurements. They allow scientists in different places to compare results and reduce errors caused by different systems of measurement.
13. An approximate value is a value close to the actual value and is often sufficient for estimation or checking reasonableness. An exact value is determined with the required precision and is necessary when small differences matter.
14. A scientific prediction is a reasoned expectation about what will happen under particular conditions, based on evidence, models, laws or theories.
15. Mathematics allows relationships between scientific quantities to be expressed precisely. Equations help scientists describe patterns, make calculations and test predictions.
Section C
16. Important details include:
- distance from school to home,
- average cycling speed,
- road or traffic conditions if they significantly affect speed.
Details such as the colour of the bicycle and the student’s clothing can usually be ignored because they do not significantly affect the travel time.
17. Models are simplified representations and may not include every factor. When new evidence becomes available or greater accuracy is required, scientists can add relevant details or modify assumptions. Therefore, models can become more accurate over time.
18.
| Scientific Law | Scientific Theory |
|---|---|
| Describes a regular pattern in nature. | Provides an explanation for why/how a pattern occurs. |
| May be expressed mathematically. | Supported by evidence and testing. |
| Focuses mainly on what happens. | Focuses mainly on explaining why/how it happens. |
A theory in science is not simply a guess.
19. Instead of saying that dark clouds guarantee rain, the student should consider measurable evidence such as humidity, wind speed and direction, temperature changes and previous weather patterns. These observations can be used to make a prediction that can later be compared with actual rainfall.
Section D
20.
a)
Volume per day = number of breaths × volume per breath
= 20,000 × 0.5 L
= 10,000 L
b) The values used are approximate estimates rather than precise measurements for every breath and every person.
c) Estimation helps us quickly judge whether an answer is reasonable and detect obviously unrealistic results.
21.
a) Two useful quantities are:
- distance to be travelled,
- average speed.
b) Traffic, road conditions, stops, weather and changes in speed can make the actual time different.
c) The colour of the car could be ignored because it has no significant effect on travel time.
Section E
22. Natural systems are often too complicated to study in complete detail. A model allows scientists to focus on the factors relevant to a particular question.
For example, in physics, a moving car may be represented as a single point when studying its motion. Its colour and internal engine structure may not be important.
In biology, a diagram of a cell highlights important structures such as the nucleus and cell membrane while leaving out many microscopic details.
Thus, simplification is deliberate. As the purpose of the investigation changes, additional details can be included to make the model more accurate.
23. Scientific thinking begins with observation and questioning. Scientists collect evidence through measurements, experiments and repeated observations. They then use this evidence to build models, explanations or predictions.
Predictions are compared with observations. If the prediction agrees with evidence, confidence in the underlying explanation increases. If it does not, scientists re-examine their assumptions, measurements or models.
This openness to correction is a major strength of science because scientific knowledge can improve when new evidence becomes available.