Nature and meaning of science

Correct answer: B. Because it may be revised when new evidence appears

Scientific knowledge is based on current evidence and may improve with new evidence. In exams understand tentative as open to revision.

Correct answer: C. Evidence and repetition

A claim becomes more reliable through evidence and repeated similar results. Popularity is not scientific support.

Correct answer: D. Amount of light

The independent variable is the factor that the investigator deliberately changes to study its effect. The dependent variable is then measured to see what happens. In this investigation, the question asks how light affects plant growth. Therefore, different amounts or durations of light may be given to plants, while plant height or another growth measure is recorded. Conditions such as plant type, soil, water, and container should normally be kept as similar as possible so the comparison is fair.

Option D is correct because the amount of light is the factor being changed. Option A, plant height, is the likely dependent variable because it is the outcome measured after the light conditions are changed. Options B and C may be controlled variables if they are kept constant, but they are not the factor named for investigation. Thus the independent variable is the amount of light.

Correct answer: A. Time taken for sugar to dissolve

The dependent variable is the outcome that is measured or observed in an experiment. Here, the student measures the time taken by sugar to dissolve at different temperatures, so the dissolution time is the dependent variable. Water temperature is the independent variable because it is deliberately changed. Exam tip: the factor changed is the independent variable, while the result measured is the dependent variable.

Correct answer: B. To limit other influences

Controlled variables keep other possible influences constant. This makes the effect of the changed factor clearer.

Correct answer: C. Observation is direct information and inference is its possible explanation

An observation is directly seen or measured while an inference is an explanation drawn from it. Keep the two terms separate in exams.

Correct answer: C. Identifying a question or problem

A scientific investigation begins by identifying a question or problem. Treat problem identification as the starting step in exams.

Correct answer: D. Evidence and testing

The direct answer is D: evidence and testing are most necessary for a reliable scientific claim. A claim is an assertion about the world, but it is not reliable merely because someone says it. First state the claim clearly, then collect relevant observations or measurements, test the claim fairly, repeat or check the work, and compare the conclusion with the evidence. D is correct because testing and evidence make a claim open to checking. A is wrong because popularity does not prove truth. B is wrong because tradition can contain useful ideas but is not proof by itself. C is wrong because personal belief is not public, testable evidence. A scientific conclusion may later be changed when stronger evidence appears. Memory cue: in science, evidence outranks popularity, tradition, and belief.

Correct answer: A. Collecting facts about phenomena

Observation provides facts and information about a phenomenon. Link observation with data collection in exams.

Correct answer: B. Because new evidence and better technology may become available

New evidence or technology can improve earlier conclusions. Remember that scientific knowledge is open to revision.

Correct answer: C. A testable possible explanation

A hypothesis is a testable possible explanation for a question. Focus on the word testable in exams.

Correct answer: A. When it can be tested using evidence

A scientific idea can be tested using evidence. Remember testability as a key feature of science.

Correct answer: A. Making the result more reliable

Repeating an experiment checks the consistency and reliability of results. Link repetition with reliability in exams.

Correct answer: A. It motivates questioning and exploration

Curiosity encourages new questions and the search for answers. Treat curiosity as the beginning of exploration.

Correct answer: A. To test a hypothesis or claim using evidence

In the scientific method, data are evidence obtained through observations and experiments. Analysing them helps determine whether a hypothesis or claim is supported. Data should not be selected merely to justify a conclusion decided in advance. Exam tip: Link the phrase “test using evidence” with the purpose of collecting scientific data.

Correct answer: B. A broad explanation supported by much evidence

A scientific theory is a broad explanation supported by extensive evidence. Do not confuse theory with a mere guess.

Correct answer: B. Recording what is actually observed

Unbiased observation records actual facts without prejudice. Connect objectivity with accurate recording in exams.

Correct answer: A. To clearly determine the effect of that factor

Changing one factor at a time helps identify its effect accurately. Remember this feature of a controlled experiment.

Correct answer: A. Because humans develop knowledge by asking questions

Humans develop scientific knowledge through observation experiments and reasoning. View science as a continuing human exploration.

Correct answer: A. To allow checking and review by others

Sharing results allows other scientists to check and review them. Link communication with verification in exams.

Correct answer: A. Checking medical advice and evidence before taking medicine

A scientific attitude checks evidence and reliable information before making decisions. Look for evidence-based daily examples in exams.

Correct answer: B. Recheck or revise the hypothesis

When results contradict a hypothesis it should be rechecked or revised. Treat honest revision as a scientific quality.

Correct answer: A. A standard unit and suitable instrument

A standard unit and proper instrument make measurement comparable and reliable. Link measurement with standardisation.

Correct answer: A. To provide a basis for comparison

A control group provides a basis for comparison with the experimental group. Connect control with comparison in exams.

Correct answer: A. Drawing valid conclusions from evidence

Reasoning helps draw valid conclusions from evidence and data. Link reasoning with forming conclusions.