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The Ever-Evolving World of Science – Class 7 Science notes, important questions and MCQs

NCERT Class 7 Science, chapter 1. Notes, key terms, important questions with answers and MCQs.

Chapter overview

Science keeps growing as people ask new questions and test ideas. Old ideas are improved or replaced when better evidence appears.

How science grows

Curiosity → observation → question → experiment → explanation.
Scientific ideas are tested by many people and can change with new evidence (e.g. Earth-centred model replaced by Sun-centred model).
Indian contributions: Aryabhata (zero, Earth's rotation), C. V. Raman (Raman effect), J. C. Bose (plant responses).

Being a young scientist

Keep a notebook of observations.
Ask "why" and "how", and try simple safe experiments.
Respect evidence even when it disagrees with what you expected.

Key terms

Observation: noticing details using our senses or instruments
Evidence: facts or data that support a claim
Inference: a conclusion drawn from observations and evidence

Formulas

Science = question + evidence + reasoning

Important questions with answers

What is the difference between an observation and an inference?2 marks

An observation is what we notice with our senses (the road is wet). An inference is a conclusion from observations (it probably rained).

Why do scientists share their results with others?3 marks

So others can check and repeat the work, find mistakes, and build on it. Ideas that many people test and confirm become more reliable.

Give an example of a scientific idea that changed with new evidence and explain why this is a strength of science.5 marks

People once believed the Earth was at the centre of the universe. Careful observations of planets by Copernicus and Galileo's telescope showed the planets, including Earth, go around the Sun. Science changes its ideas when better evidence comes, so its knowledge keeps getting more accurate; it does not hold on to wrong ideas just because they are old.

Quick revision

Science changes with evidence.
C. V. Raman won the Nobel Prize in Physics (1930).
Experiments must be safe and fair.

Exam tips

In answers, separate what you observed from what you concluded.
Name the scientist with the discovery in GK-type questions.

Practice MCQs

Science starts with
1. guessing answers
2. curiosity and questions
3. copying
4. memorising only
Show answer
Answer: (b) curiosity and questions. Questions drive science.
The Raman effect was discovered by
1. C. V. Raman
2. J. C. Bose
3. Homi Bhabha
4. Aryabhata
Show answer
Answer: (a) C. V. Raman. C. V. Raman.
Why do scientific ideas change over time?
1. new evidence is found
2. scientists forget
3. books are lost
4. rules change randomly
Show answer
Answer: (a) new evidence is found. Evidence improves ideas.
Which is an observation, not a conclusion?
1. the leaf turned yellow in the dark box
2. plants need light
3. light makes food
4. all plants die in the dark
Show answer
Answer: (a) the leaf turned yellow in the dark box. It describes what was seen.
A scientific idea changes when
1. a famous person disagrees
2. new evidence shows it is incomplete
3. it becomes old
4. people stop liking it
Show answer
Answer: (b) new evidence shows it is incomplete. Science updates with evidence.
The Sun-centred model replaced the Earth-centred model because
1. it was older
2. kings ordered it
3. it explained observations better
4. it was simpler to draw only
Show answer
Answer: (c) it explained observations better. Better explanation of planetary motion.
A good scientist, when an experiment gives an unexpected result, should
1. ignore it
2. stop experimenting
3. change the data
4. check and repeat it
Show answer
Answer: (d) check and repeat it. Verify before concluding.
Which is an observation, not an inference
1. The leaves have yellow spots
2. The plant is dying because of pests
3. The soil must be poor
4. It needs more sun
Show answer
Answer: (a) The leaves have yellow spots. Directly seen.

All chapters of Class 7 Science

Written by Kundali IQ from standard, well-established facts to help with revision. This is not an official NCERT publication; always read your textbook too.