Section A
- b
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Section B
11. A model is a simplified representation of a real system. It helps scientists focus on the features important to a particular question.
12. A theory is considered reliable because it is supported by evidence and repeated testing. Revision does not make it unreliable; it allows scientific knowledge to improve when better evidence becomes available.
13. Estimation does not provide an exact value. Its accuracy depends on the assumptions and approximate values used.
14. A testable prediction can be compared with observations or measurements. This allows scientists to determine whether their model or explanation is supported by evidence.
15. Mathematics can be used to relate distance and time when studying motion, analyse experimental data, or estimate quantities such as energy and population growth.
Section C
16. A model becomes easier to use when irrelevant details are removed. For example, when studying the motion of a car, its colour and interior design can be ignored. Distance, time and speed are more relevant.
17. Symbols make scientific communication concise and precise. Units tell us the scale in which a quantity has been measured. Together they allow scientists to communicate and compare results clearly.
18. An incorrect prediction provides useful evidence. It may reveal an incorrect assumption, a limitation of the model or an error in measurement. Scientists can then investigate and improve their understanding.
19. A student should ask what evidence supports the claim, whether the claim can be tested, what observations or measurements are available, and whether reliable scientific sources support it. Repetition of a claim does not make it scientifically true.
Section D
20.
a) Questions could include:
- What physical change occurs during an eclipse?
- Does the temperature of the food change significantly?
- Is there a known physical, chemical or biological mechanism that makes food harmful during an eclipse?
b) Evidence could include controlled observations, measurements of food quality and information from established scientific studies.
c) A claim should be evaluated using evidence rather than popularity. A large number of people repeating a statement does not establish that the statement is scientifically correct.
21.
a)
10,000 × 4 = 40,000 breaths per day
b) Breathing rate varies with age, activity, health, sleep and other conditions.
c) Estimation gives a quick and reasonable idea of the scale of the quantity without requiring continuous measurement of every breath.
Section E
22. Scientific knowledge develops through a continuing process of observation, questioning, measurement, experimentation and reasoning.
Scientists use evidence to identify patterns and construct models or explanations. These models can be used to make predictions. Scientists then compare the predictions with observations.
If observations support the prediction, confidence in the model increases. If observations disagree, scientists examine their assumptions, measurements or explanations and may modify the model.
Therefore, scientific knowledge is not simply a fixed collection of facts. It develops as evidence becomes better and explanations are tested and refined.
23. “Science has no walls” means that nature itself is not divided into school subjects. Different branches of science often work together.
For example, understanding a surgical mask can involve:
- Physics — particle motion and airflow,
- Chemistry — properties of polymer fibres,
- Biology — microorganisms and their behaviour,
- Mathematics — analysing filtration and airflow data.
Similarly, climate change involves physics, chemistry, biology, earth science and mathematics.
Interdisciplinary thinking helps scientists solve complex real-world problems that cannot be understood using only one branch of science.