Nature and meaning of science

Correct answer: C. Examine the method and evidence of the new study

The method and reliability of an opposing result must be examined. Choose balanced evaluation of evidence in exams.

Correct answer: A. Keep temperature constant

Keeping temperature constant allows the effect of light to be isolated. Control confounding variables in exams.

Correct answer: B. It should make testable predictions

A scientific hypothesis should produce a prediction that can be tested. Identify testability in exams.

Correct answer: C. Precise but inaccurate

Closely grouped values show precision but distance from the true value shows inaccuracy. Distinguish accuracy from precision.

Correct answer: B. Confirmation bias

Selecting only supportive results is confirmation bias. Choose unbiased reporting of all relevant data.

Correct answer: C. A decrease in one event causes a decrease in the other

When two events decrease together, the data may show correlation, but this does not prove that a decrease in one causes the decrease in the other. A third factor may be affecting both events. A causal conclusion needs controlled investigation, adequate evidence, and checks for other possible causes. Exam tip: correlation is not proof of causation.

Correct answer: B. Because theories are explanations supported by extensive evidence

A scientific theory is supported by many tests and evidence. Distinguish its scientific meaning from everyday usage.

Correct answer: A. It describes a natural pattern

A scientific law describes a regularly observed relationship. Do not treat it as a stage leading to theory.

Correct answer: B. Reproducibility

Obtaining the same result independently demonstrates reproducibility. Link it with reliability.

Correct answer: B. Measurement validity and repetition are difficult to assess

Without a clear measurement method the quality of the result is difficult to assess. Understand the importance of operational definitions.

Correct answer: B. Selection bias may be reduced

Random selection reduces the chance of unintentionally favouring certain types in the population. Link it with unbiased sampling.

Correct answer: B. The conclusion may still misrepresent the population

A large sample is not automatically a good sample. Sample size tells us how many members were studied, while selection quality tells us whether those members fairly represent the population. If a sample is chosen in a biased way, some groups may be included too often and others may be left out. Repeating that biased selection with many people can produce a precise-looking result that is still unfair or unrepresentative. Increasing size can reduce some random variation, but it cannot remove systematic selection bias.

For example, asking only one neighbourhood about the preferences of an entire city may give a large number of responses, yet the city’s other neighbourhoods are not represented. The conclusion may therefore misrepresent the population. Option B is correct. A large biased sample does not become random by itself, and data remain necessary. Both sample size and the method of selection must be considered.

Correct answer: A. It can show important relationships in a simplified form

A model simplifies important features to aid understanding and prediction. Recognise both its usefulness and limits.

Correct answer: A. Repeatability concerns consistency while validity concerns measuring the intended thing

Repeatability concerns obtaining similar results while validity concerns appropriateness of measurement. Distinguish the two.

Correct answer: A. The observed effect may be linked to the independent variable

Keeping other variables constant isolates the effect of the independent variable. Identify controlled experiments for causal testing.

Correct answer: B. There is a lack of transparency and scientific honesty

Presenting a post-experiment change as predetermined violates transparency. Link accurate records with scientific ethics.

Correct answer: B. Check the measurement and possible error

The cause of an unusual value should be checked and any removal scientifically documented. Choose transparent data analysis.

Correct answer: A. Similarities and differences in population, conditions, and other relevant factors between the region and the whole country

A conclusion from a small region can be applied to the whole country only if the people and conditions in that region adequately represent those of the country. Therefore, similarities and differences in population, social and geographical conditions, and other relevant factors must be checked. The number of diagrams in a report or the researcher’s residence does not determine whether findings can be generalised. Exam tip: For such questions, focus on sample representativeness and generalisation of findings.

Correct answer: B. Ask for the original data and scale

Original data and axis scales are needed to interpret a graph correctly. Critically examine visual presentations.

Correct answer: A. The treatment caused the change

Without a control group it is difficult to establish that the treatment caused the change. Look for a comparison group in causal claims.

Correct answer: A. It is difficult to test further

Direct answer: Option A, it is difficult to test further. A scientific explanation should not only fit observations already known; it should also lead to new predictions that can be checked by observation or experiment. Reasoning step by step: an explanation describes why events occur; a new prediction follows from that explanation; researchers test the prediction; the result can support, modify, or challenge the explanation. If an explanation makes no new prediction, there is no clear new situation in which it can be tested, so its predictive power and usefulness are limited. Option A is correct. Option B is too strong: lack of new predictions does not prove that the explanation must be false. Option C is wrong because an explanation does not automatically become a law; laws and explanations have different roles. Option D is wrong because an explanation may contain logical reasoning even when its predictions are limited. Exam cue: a useful scientific explanation must be testable and have predictive power.

Correct answer: B. Reproduction by other independent institutions

Similar results from independent institutions strengthen the evidence. Identify independent verification.

Correct answer: B. Double-blind testing

Double-blind testing reduces both expectation and observer bias. Remember the purpose of blinding.

Correct answer: A. Self-reported information may be affected by expectation or memory

Self-reported information can be useful but may contain bias. Identify limitations of evidence.

Correct answer: A. Misleading presentation of selected data

Showing only data that support a claim can make the conclusion biased or misleading because contrary or different results are hidden. Therefore, this is a misleading presentation of selected data. Accurate measurement concerns the precision of data, not the omission of inconvenient results. Exam tip: When reading a graph, check whether the complete data set and a suitable scale are shown.