Nature and meaning of science

Science understands natural phenomena through evidence and reasoning. Remember the purpose of science for the exam.

The direct answer is B: evidence. Science accepts an idea when observations, measurements, experiments, or other reliable evidence support it. The reasoning is step by step: first a claim is proposed; then it is tested or checked; results are recorded; other people may examine the method and results; finally, the idea is accepted provisionally when the evidence supports it. Scientific knowledge can later be revised if stronger evidence appears. Option A, popularity, is wrong because many people may believe an idea that has not been tested. Option B is correct because evidence connects a scientific claim with observable support. Option C, tradition, is wrong because an old belief is not automatically scientifically true. Option D, personal preference, is wrong because liking an idea does not show that it matches nature or facts. The question asks what is most necessary for accepting an idea, not what makes an idea attractive. Memory cue: in science, ask “What is the evidence?”

Scientific study usually starts with an observation or question. Treat it as the first step in sequence-based questions.

Observation involves collecting facts through senses or instruments. Careful noticing is its key feature.

A scientific question can be investigated through observation or experiment. Remember the term testable.

The main purpose of an experiment is to test an idea, hypothesis, or prediction under controlled conditions. Therefore, option B is correct. Changing the result is not the aim of an experiment; scientists record results objectively. Exam tip: In questions about experiments and observations, look for options related to testing or investigation.

The direct answer is C: a hypothesis is a testable possible explanation. In science, a question comes first, such as asking why a plant grows differently in two conditions. A scientist then proposes a possible answer that can be checked by observation or experiment. Step by step: identify the question; suggest a reasonable explanation; make a prediction; collect evidence under suitable conditions; compare the evidence with the prediction; and revise or reject the hypothesis if needed. Option C is correct because it includes both possibility and testability. A is wrong because a hypothesis is not final truth; evidence may support or reject it. B is wrong because a scientific hypothesis must respond to a question or problem, not be a story without one. D is wrong because an instrument is a tool used for measurement, not an explanation. Memory cue: hypothesis means “testable idea,” not “proved fact.”

A conclusion is based on evidence obtained from experiments and observations. Write conclusions according to results.

Science uses organised methods such as observation and experimentation. Systematic means organised.

Reasoning helps interpret evidence and reach valid conclusions. Reasoning and evidence work together.

A scientific attitude involves asking questions and seeking evidence. Curiosity is a key feature.

Direct answer: D. Scientific knowledge can be revised when new, reliable evidence appears. Science is a careful way of asking questions, observing, measuring, testing explanations and checking results. Step by step: a scientist proposes an explanation, makes a testable prediction, collects evidence, compares the result with the prediction and communicates the findings. If stronger evidence later shows that an explanation is incomplete or inaccurate, scientists improve or replace it. This does not make science weak; it makes scientific knowledge self-correcting and evidence-based. Option A is wrong because scientific ideas are not permanently unchangeable. Option B is wrong because science is not based only on belief; evidence and testing are central. Option C is wrong because scientific claims must be open to investigation and checking. Option D is correct because revision in light of evidence is a key feature of science. Memory cue: science changes with evidence, not with mere opinion.

Curiosity initiates new questions and discoveries. Being curious is important for scientific thinking.

Science values evidence and testing while superstition is often accepted without evidence. Remember this distinction.

Repeating an experiment shows whether similar results are obtained consistently. Repetition increases reliability.

Measurement gives a scientific observation a clear numerical value and, where needed, a unit. Instead of saying vaguely that something is large, hot, or fast, a scientist can record a length, temperature, or time. Such information can be checked, repeated, and compared with results from another object or another experiment. Measurement therefore makes observations more precise and supports fair conclusions based on evidence.

Option D is correct because precise and comparable information is the main scientific benefit of measurement. Decoration has no role in collecting evidence, and measurement does not hide guesses or reduce the need to ask questions. A measurement may not be perfectly exact because instruments have limits, but it is still more reliable and useful than an unsupported description.

Describing colour is a qualitative observation because it does not use a number. Qualitative observations describe qualities.

A quantitative observation measures a characteristic using a number and a standard unit. Saying that a plant is 20 cm tall is based on measurement, so it is quantitative. In contrast, describing a leaf as smooth or a stone as hard states a quality without a numerical measurement; these are qualitative observations. Exam tip: An observation containing a number or measurement unit is usually quantitative.

The direct answer is C: a variable is a factor that can change or be measured in an experiment. In a simple plant investigation, the amount of water may be changed, plant growth may be measured, and sunlight or soil may be kept the same. The factor deliberately changed is often called the independent variable; the observed result is the dependent variable; factors kept unchanged are controlled variables. At this level, the key idea is simply that a variable can have different values. Option A is wrong because something that always remains the same is a control or constant, not a changing variable. Option B is wrong because an experiment title only names the investigation. Option C is correct because it gives the meaning of variable. Option D is wrong because a laboratory room is a place, not automatically a factor being changed or measured. Do not confuse every object in a laboratory with a variable: it becomes a variable only when its relevant value can change or be observed in the investigation. Memory cue: variable means “value can vary.”

In a fair test conditions other than the tested factor are kept the same. This makes comparison valid.

Recording results preserves evidence and allows analysis. Clear records are part of scientific work.

Scientific communication shares findings and results with others. The idea of sharing is important.

The direct answer is C: verification means checking a claim using evidence or experiment. Science does not accept a statement merely because someone says it confidently. Step by step: state the claim clearly; decide what evidence would support or challenge it; observe, measure, or perform a controlled experiment; record the results; and compare them with the claim. Repeating checks and allowing others to examine the evidence makes the conclusion more reliable. Option C is correct because it directly describes evidence-based testing. A is wrong because accepting without checking is the opposite of verification. B is wrong because changing results destroys honesty and does not verify anything. D is wrong because memorising names may help recall facts, but it is not checking a claim. Verification does not always prove an idea absolutely; it shows whether available evidence supports it and whether further testing is needed. Memory cue: verify means test before trust.

Scientific models explain complex objects or processes in a simplified form. A model is a useful representation of reality.

Science helps solve problems in many areas including health and technology. Remember daily-life examples.