The Ever-Evolving World of Science – Long Answer Type Questions

Ans. Science may be defined as a systematic and organised way of studying the natural world through careful observations, experiments and logical reasoning. It is not just a collection of facts, but a method of finding out how nature works.

It is called systematic because it follows fixed steps. A scientist does not jump to conclusions. First, they observe an event, then ask questions, form a possible answer (hypothesis), test it through experiments, collect data and finally draw a conclusion. It is organised because scientific information is arranged in an orderly manner, so that others can understand, repeat and verify it. This step-by-step and well-planned process makes science a reliable way of gaining knowledge about the world around us.

Ans. Saying that science is more than just facts means that science is not limited to remembering definitions or formulas. It is actually a way of thinking and working.

Firstly, science asks us to be curious. Instead of accepting everything as it is, we are encouraged to ask “why”, “how” and “what if”. Secondly, science demands evidence. Any idea becomes scientific only when it is supported by observations or experiments. Thirdly, science is open to change. If new evidence is found, scientific ideas may be improved or replaced. Finally, science trains us to follow a proper method – observe, test and reason – before we accept anything as true. Therefore, science is a complete process and attitude, not just information printed in a textbook.

Ans. Science is described as an “ever-evolving world” because scientific knowledge is never final. As new tools and techniques are developed, we are able to collect better data and understand things in more detail.

For example, long ago people believed that the Earth was flat. With improved observations and journeys, scientists proved that the Earth is spherical. Similarly, the model of the atom has changed over time as new experiments were done. Earlier, diseases were thought to be caused by bad air or evil spirits. Later, with the help of microscopes, scientists discovered germs and developed vaccines and medicines. These examples show that science keeps growing and correcting itself. This continuous development is why we call it an ever-evolving world of knowledge.

Ans. Some important features of the nature of science are:

• Based on observation and evidence: Scientific ideas are supported by what we can observe, measure or test. They are not accepted without proof.
• Logical and rational: Science uses clear reasoning. Conclusions are drawn step by step, using facts and not emotions or blind beliefs.
• Testable and repeatable: Scientific explanations can be tested by experiments that can be repeated by other people. If they get the same result, the explanation becomes stronger.
• Changing and self-correcting: Science is not fixed. When new evidence appears, earlier ideas may be improved or replaced. This makes scientific knowledge more accurate over time.

These features together make science a trustworthy and powerful way to understand the world.

Ans. This chapter introduces scientific inquiry in a simple and friendly manner. It does not use very difficult terms but explains the main steps in easy language. Students learn that scientific inquiry begins with observations, such as noticing patterns around them. From these observations, they move to questions, for example, “Why does one plant grow better than another?”

The chapter then explains how students can form hypotheses (possible answers) and test them with simple experiments. It highlights the importance of recording data carefully and then drawing a conclusion. By following these steps through simple examples, the chapter gives Class 7 students a clear idea of how scientists investigate problems and how they too can think like young scientists in their daily lives.

Ans. Science does not accept any statement just because it is old or popular. Every scientific idea must be supported by evidence. If someone makes a claim, scientists demand experiments, observations or measurements to prove it. If such proof is not available, the claim is not accepted as scientific.

For example, earlier people believed that thunder and lightning were caused by angry gods. Science showed that they are natural electrical phenomena in the atmosphere. Similarly, superstitions about eclipses or comets have been replaced by scientific explanations. This shows that science is based on tested facts, not on blind belief. This nature of science encourages us to question, test and understand, instead of simply trusting anything without checking.

Ans. The scope of science is extremely wide. At one end, it includes the study of very tiny particles that we cannot see with our eyes, such as atoms, molecules, germs and cells. Scientists use powerful microscopes and instruments to study them. At the other end, science also studies very large objects like mountains, oceans, planets, stars and galaxies. Telescopes and spacecraft help in these studies.

Science also covers everything in between – plants, animals, human body, machines, energy, weather, soil, water and even the air we breathe. For example, Biology explains how our heart works, Chemistry explains the composition of water and Physics explains how a fan rotates. This shows that from the smallest particle to the largest galaxy, the scope of science truly covers the whole natural world.

Ans. The three main branches of science are:

• Physics: It deals with motion, force, energy, sound, light, electricity and magnetism. Examples from daily life include the working of a ceiling fan (electricity and motion), reflection of our face in a mirror (light) and sound from a speaker.
• Chemistry: It studies substances, their properties and the changes they undergo. Rusting of iron, digestion of food, making of soap or plastic and burning of fuels are all explained using Chemistry.
• Biology: It is the study of living organisms – plants, animals and humans. Processes such as breathing, photosynthesis, growth, reproduction and diseases come under Biology.

These branches are separated for convenience of study, but in real life, they are closely connected and often work together to explain a situation completely.

Ans. Earth science is the branch of science that studies the Earth and its surroundings. It includes the study of rocks, soil, water, atmosphere, weather, climate, earthquakes, volcanoes and natural resources. It helps us understand how Earth changes over time and how we can use its resources wisely.

Astronomy is the branch of science that studies objects outside the Earth’s atmosphere, such as the Sun, Moon, planets, stars and galaxies. It explains how planets move, how stars are formed and what lies in outer space. Together, Earth science and astronomy help us understand both our home planet and the vast universe around it, giving us a complete picture from local to cosmic level.

Ans. Many real-life topics cannot be explained by just one branch of science. For example, consider the topic of human health. To understand health completely, we need:

• Biology – to study the structure and function of organs like heart, lungs and kidneys.
• Chemistry – to understand the role of nutrients, hormones, medicines and chemical reactions like digestion.
• Physics – to explain blood pressure, flow of blood, mechanics of movement and working of medical machines like X-ray or ECG.

This shows that different branches work together to explain a single topic. Modern fields such as environmental science, biotechnology and robotics depend on this combined knowledge from many branches of science.

Ans. The Class 7 NCERT Science book follows an integrated approach because at this stage it is more important for students to see connections rather than divisions. Instead of giving separate books of Physics, Chemistry and Biology, NCERT presents chapters that mix ideas from all three wherever needed.

For example, a chapter on “Heat” may involve Physics, but a chapter on “Nutrition in Plants” uses Biology and Chemistry. This integrated method helps students understand that science is one complete subject explaining the natural world. It also makes learning easier and more interesting because students can see how different concepts support each other. Later, in higher classes, when these branches are taught separately, students already have a strong combined base to build on.

Ans. When students know the scope and branches of science, they understand the variety of topics that science covers. This knowledge helps them identify which areas they find most interesting – such as living organisms, machines, chemicals, Earth or space. As they move to higher classes, they can make better decisions about which subjects to choose and which careers to explore.

For example, a student interested in plants and animals may choose Biology and later pursue fields like medicine, agriculture or wildlife biology. A student who enjoys machines and energy may move towards engineering or technology. Thus, understanding the branches and scope of science early in Class 7 guides students towards suitable higher studies and future careers.

Ans. Science is present in almost every activity at home:

• Cooking food: When we cook, we use heat, a concept from Physics, and chemical changes, a concept from Chemistry. For example, boiling, frying and baking are all scientific processes that change raw food into cooked food.
• Using electrical appliances: Fans, lights, televisions, refrigerators and mixers work on electricity. They use scientific principles of electric current, circuits, motors and cooling systems.
• Cleaning and washing: Soaps and detergents are chemical substances designed to remove dirt and oil. They work because of their special molecular structure studied in Chemistry.
• Health and hygiene: Thermometers, medicines and disinfectants used at home are products of science. Understanding germs and how they spread helps us maintain cleanliness.

These examples show that ordinary home activities are closely connected with scientific ideas and inventions.

Ans. Science has completely transformed travel and communication. Earlier, people travelled on foot or used animals and simple carts, taking many days to reach distant places. Today, scientific knowledge has given us bicycles, cars, buses, trains, ships and aeroplanes. These use engines, fuels, aerodynamics and other scientific principles to move quickly and safely, allowing us to travel hundreds of kilometres in a few hours.

In communication, letter writing was once the main method and messages took days to reach. With advances in science and technology, we now have telephones, mobiles, internet, email, video calls and social media. These work on the principles of electricity, electromagnetism, radio waves and digital technology. We can now talk to people across the world instantly and share pictures and videos in seconds. This enormous change is due to the application of science in our daily lives.

Ans. Science has played a major role in improving healthcare. Earlier, many people died from infections like smallpox, polio and plague. Today, because of scientific research, we have vaccines that protect us from many deadly diseases. Antibiotics and other medicines cure infections and help us recover faster.

Modern scientific instruments such as X-ray machines, ECG, MRI and blood testing equipment help doctors correctly diagnose diseases. Operations that were once impossible can now be done with the help of advanced surgical tools and anaesthesia. Better knowledge of nutrition, hygiene and sanitation, which is also based on science, has reduced illnesses. All these factors put together have increased human life expectancy. People now live longer and healthier lives compared to earlier generations.

Ans. Science has made life easier in many ways. It has given us electricity, vehicles, computers, mobile phones, modern medicines and many household appliances. These save time and effort, increase comfort and improve health. For example, washing machines reduce manual work, and fast transport helps us reach schools and offices quickly.

However, misuse or overuse of scientific inventions has created new problems. Vehicles and factories that make our lives comfortable also release smoke and gases that pollute air. Plastic products are useful, but improper disposal pollutes land and water. Excessive use of gadgets can affect our health and social life. Harmful weapons created using science can destroy life and property. So, while science itself is not bad, it must be used wisely and responsibly to avoid these problems and protect our environment.

Ans. This chapter explains that science is not limited to laboratories or textbooks. It encourages students to look around and identify science in simple things. For instance, when we see clothes drying in the sun, we can think of evaporation. When we switch on a light, we can think of electricity and energy. When we see plants growing towards light, we can relate it to growth and response.

By giving such examples and asking students to observe, the chapter trains our minds to recognise the presence of science in cooking, cleaning, transport, communication, games and health. Once we start thinking in this way, our surroundings become a “living science laboratory”, helping us understand concepts better and remember them for a longer time.

Ans. It is important to understand the benefits of science because they show us how useful scientific knowledge is. Knowing the advantages motivates us to study science seriously and use it to solve problems in areas like health, environment, agriculture and technology.

At the same time, we must know the limitations and dangers so that we do not misuse scientific inventions. Science cannot answer questions about personal beliefs and values, and wrong use of science can cause pollution, accidents and even wars. Understanding both sides helps students become responsible citizens. They can enjoy the comforts provided by science while taking care of nature and respecting human values. This balanced view is necessary for a safe and sustainable future.

Ans. A scientific attitude is a way of thinking in which a person is curious, logical, honest and open-minded. Such a person does not accept statements blindly. Instead, they look for reasons and evidence.

Main characteristics include:

• Curiosity: Wanting to know why things happen. For example, a student wonders why iron rusts and tries to find the reason.
• Logical thinking: Reaching conclusions step by step. For instance, checking all possible reasons before deciding why a plant died.
• Honesty: Reporting observations truthfully, even if they do not support one’s guess.
• Open-mindedness: Being ready to change one’s opinion when new proof is found.

This chapter encourages students to develop these qualities in their daily life and studies.

Ans. A Class 7 student can carry out a simple scientific inquiry as follows:

• Step 1 – Observation: The student observes that a plant kept near a window grows better than one in a dark corner.
• Step 2 – Question: The student asks, “Does a plant grow better in light than in darkness?”
• Step 3 – Hypothesis: The student suggests, “Plants need sunlight to grow properly, so a plant in light will grow taller than one in darkness.”
• Step 4 – Experiment: Two similar plants are taken. One is kept in sunlight and the other in a dark place. Both get equal water and soil.
• Step 5 – Data collection: The height and condition of both plants are noted every day for about two weeks.
• Step 6 – Conclusion: If the plant in sunlight grows better, the hypothesis is supported. The student then concludes that light is necessary for healthy plant growth.

This is a simple example of scientific inquiry using observation, hypothesis, experiment and conclusion.

Ans. Consider the example of drying clothes faster on a windy day:

• Observation: We notice that clothes dry faster outside on a windy day than inside a closed room.
• Hypothesis: We guess that “Moving air helps water evaporate faster from clothes.”
• Experiment: We hang two similar wet towels – one under a fan (moving air) and one in a still corner. Both are left for the same time. We observe which one dries faster.
• Conclusion: If the towel under the fan dries first, our hypothesis is supported and we conclude that moving air increases the rate of evaporation.

This simple example shows how these four terms are linked in scientific inquiry and how even daily experiences can be studied scientifically.

Ans. Recording and analysing data are important because they make scientific work clear, reliable and open to checking by others. When scientists do experiments, they measure or note changes, such as time taken, height of plants or temperature. If these observations are not written down properly, important information can be forgotten or confused.

By putting data in tables, charts or graphs, scientists can easily compare different results, find patterns and decide whether the hypothesis is correct. Data also allow other scientists to repeat the same experiment and check whether they get similar results. Without proper data, scientific conclusions would just be guesses. Therefore, careful recording and honest analysis of data are central to the scientific method.

Ans. The chapter explains that science accepts ideas only when they are supported by evidence. It gives examples where natural causes explain events that were earlier linked to superstitions. For instance, diseases are caused by germs and unhealthy habits, not by bad luck. Eclipses are due to the positions of the Sun, Earth and Moon, not because something unlucky is happening.

By showing that there are logical and natural reasons behind such events, the chapter encourages students to question superstitions and not be afraid of them. It guides them to ask “Is there a scientific explanation?” and to look for facts. This habit helps students to become rational, confident and free from unnecessary fear and wrong beliefs.

Ans. Practising scientific inquiry and attitude from a young age trains the mind to think clearly and carefully. Children who learn to observe closely, ask questions, test ideas and look for proof become better problem-solvers in all areas of life, not just in science.

They can make informed decisions about health, environment, studies and even daily choices like saving energy. They learn to separate facts from rumours and are less likely to be misled. Over time, these students become responsible citizens who can understand scientific issues in society, such as pollution or vaccination, and take sensible actions. Therefore, starting scientific thinking early builds a strong foundation for higher studies and for a thoughtful adult life.

Ans. Some simple scientific instruments used in school are the thermometer, measuring cylinder, spring balance and magnifying glass.

• The thermometer measures temperature. It helps us compare how hot or cold different substances are, rather than just feeling with our hand.
• The measuring cylinder is used to measure the volume of liquids accurately. It has markings that show the amount of liquid in millilitres.
• The spring balance measures force or weight. It allows us to see how heavy an object is using standard units like newton.
• The magnifying glass helps us see small objects clearly by making them appear bigger.

These instruments reduce guesswork and make observations more exact, which is very important in science.

Ans. Standard units are fixed units of measurement that are accepted all over the world, such as metre (m) for length, kilogram (kg) for mass and second (s) for time. They are necessary in science to avoid confusion and to make sure everyone understands measurements in the same way.

For example, if one person measures length using hand-spans and another using footsteps, their results will differ and cannot be compared. But if both use metre scales, their readings can be accurately shared and checked. Similarly, standard units allow scientists in different countries to share data and work together. Without standard units, scientific experiments and results would not be reliable or useful globally.

Ans. Five important safety rules are:

• Do not taste or smell chemicals directly: Many chemicals can be poisonous or irritating. Tasting or smelling them closely can harm our body.
• Handle glassware carefully: Test tubes, beakers and flasks can break easily. Broken glass can cause cuts and injuries, so they must be used gently.
• Do not run or play in the lab: Running or pushing may lead to accidents, such as spilling chemicals or breaking apparatus.
• Follow the teacher’s instructions: Teachers know the correct and safe methods. Ignoring instructions can cause wrong results or dangerous situations.
• Keep the lab clean and tidy: Properly placing apparatus and cleaning spills immediately reduces the chance of accidents and makes work easier.

Following these rules keeps everyone safe and allows experiments to be done smoothly.

Ans. Ethics in science refers to following moral principles while doing scientific work. This includes being honest, fair and careful, and ensuring that experiments do not harm people, animals or the environment.

Honesty is important because other scientists and the public depend on scientific results. If a scientist changes data or lies about results, it can lead to wrong conclusions and dangerous decisions, for example, using a medicine that does not really work. Responsibility means understanding how scientific discoveries will be used and making sure they help society instead of causing harm. Ethical behaviour builds trust in science and ensures that knowledge is used for the benefit of all.

Ans. Science cannot answer all kinds of questions. It mainly deals with questions about the natural world that can be observed and tested. For example, science can answer: “Why does rain fall?”, “How does the heart pump blood?” or “What causes an eclipse?” These questions are about natural events and can be studied through experiments and observations.

However, science cannot answer questions about personal beliefs or values, such as “Which festival is the most important?”, “Is this painting beautiful?” or “Which religion is correct?” These questions depend on individual opinions, culture and faith, not on experiments. Therefore, we must understand that science is powerful but limited to certain types of questions only.

Ans. This chapter lays the foundation for all other chapters in Class 7 Science and for higher classes. It explains what science is, how it works and why it is important in our daily life. By learning about observations, experiments, hypotheses and conclusions, students understand the scientific method that will be used in later topics like heat, acids and bases, motion, electric current and environmental issues.

The chapter also builds a scientific attitude, teaching students to be curious, logical and evidence-based. It introduces the idea that science is ever-evolving and interconnected, which helps in linking different topics across the textbook. When students move to higher classes and face more difficult scientific concepts, this basic understanding of the nature and scope of science makes it easier for them to grasp new ideas and apply them in real life and examinations.