CBSE Class 9 Science Chapter 02 Cell The Building Block Of Life MCQs Set 03

Download CBSE MCQs for Class 9 Science: Chapter 02 Cell The Building Block Of Life

Access targeted multiple-choice questions for Chapter 02 Cell The Building Block Of Life designed to align with the latest CBSE academic syllabus for Class 9 Science. These objective practice sets help students evaluate their conceptual understanding and improve exam readiness.

Chapter-wise Objective Questions: Chapter 02 Cell The Building Block Of Life

Access the complete set of multiple-choice questions for Chapter 02 Cell The Building Block Of Life below. This focused format allows students to isolate specific topics for thorough review and uninterrupted practice alongside official CBSE textbooks.

Question: In physics, a moving car is sometimes modelled as a single point rather than as its actual shape. What is the reasoning behind this?
A. The car's exact size and shape usually do not affect the answer to the motion question being studied, so treating it as a point keeps the model simple
B. Cars are physically shaped like points at high speed
C. Scientists cannot draw complicated shapes accurately
D. A point representation is required by international measurement standards
Show Answer & Explanation

Answer: (A) The car's exact size and shape usually do not affect the answer to the motion question being studied, so treating it as a point keeps the model simple

Explanation:
Models are built by keeping only what matters for the question at hand. Since the car's shape rarely changes the answer to questions about its motion, dropping that detail makes the model easier to work with without losing accuracy.

Question: In chemistry, atoms and molecules are drawn as spheres joined by lines representing bonds. What does this representation achieve?
A. It gives a workable visual model of structure and bonding without needing to depict the true complexity of atoms
B. It shows exactly what atoms look like under a microscope
C. It replaces the need for any experiments in chemistry
D. It proves that atoms are literally round objects
Show Answer & Explanation

Answer: (A) It gives a workable visual model of structure and bonding without needing to depict the true complexity of atoms

Explanation:
Spheres-and-sticks diagrams are a simplification, not a photograph of reality. They let chemists reason about bonding and structure clearly, which is the whole point of a scientific model.

Question: How does the chapter say biology typically simplifies a cell when building a model of it?
A. By drawing a diagram that highlights only the parts important for the idea being studied
B. By listing every molecule present inside the cell
C. By photographing the cell under maximum magnification
D. By describing the cell using only mathematical equations
Show Answer & Explanation

Answer: (A) By drawing a diagram that highlights only the parts important for the idea being studied

Explanation:
• A cell diagram is not a full inventory of everything inside it
• Only the structures relevant to the concept being taught are shown
• This is the same modelling idea used across physics, chemistry and earth science

Question: According to the chapter, how is the Earth often simplified when it is studied as a model in earth science?
A. As a smooth sphere divided into distinct layered regions
B. As an irregular cube with jagged edges
C. As a flat disc floating in space
D. As a single uniform solid mass with no internal structure
Show Answer & Explanation

Answer: (A) As a smooth sphere divided into distinct layered regions

Explanation:
Treating the Earth as a smooth, layered sphere strips away surface irregularities like mountains and valleys, leaving a manageable model that still captures the planet's internal structure.

Question: Which everyday experience does the chapter use to show how a scientific law explains a familiar pattern?
A. The jerk felt when a bus stops suddenly, explained through Newton's laws of motion
B. The taste of food changing when it is heated
C. The colour of the sky changing at sunset
D. The sound a bell makes when struck
Show Answer & Explanation

Answer: (A) The jerk felt when a bus stops suddenly, explained through Newton's laws of motion

Explanation:
A law describes a regular, repeatable pattern in nature. Newton's laws of motion account for that sudden jerk passengers feel, which is exactly the kind of everyday regularity the chapter uses to define what a law is.

Question: The chapter's discussion on weather forecasting lists several factors that make predictions uncertain. Which of these is part of that explanation?
A. Small differences in temperature, pressure, humidity and wind can grow into very different outcomes over time
B. Weather forecasters intentionally give wrong answers
C. Clouds always guarantee rain within a few hours
D. Weather has no measurable factors at all
Show Answer & Explanation

Answer: (A) Small differences in temperature, pressure, humidity and wind can grow into very different outcomes over time

Explanation:
• Weather depends on many changing quantities
• Tiny variations in these quantities can amplify over time
• That is why forecasts stay reliable only for short periods ahead, not far into the future

Question: A Pause and Ponder activity asks students to recall a prediction their family recently made, such as guessing a cricket match's outcome. What is this activity mainly encouraging students to think about?
A. Whether the prediction relied on evidence and reasoning or was mostly a guess, and how scientific thinking could improve it
B. The exact rules of cricket used in international matches
C. How to calculate the speed of a cricket ball scientifically
D. Why sports predictions are always inaccurate
Show Answer & Explanation

Answer: (A) Whether the prediction relied on evidence and reasoning or was mostly a guess, and how scientific thinking could improve it

Explanation:
The activity is not really about cricket at all; it nudges students to notice the difference between a reasoned, evidence-backed prediction and simple guesswork, and to consider how scientific habits could sharpen everyday predictions.

Question: In the example explaining how a surgical mask works, which branch of science is connected to understanding the material properties of the fibres used in the mask?
A. Chemistry
B. Earth science
C. Mathematics
D. Astronomy
Show Answer & Explanation

Answer: (A) Chemistry

Explanation:
The mask example splits the problem across disciplines: chemistry accounts for the polymer fibre properties, while physics, biology and mathematics each explain a different piece of how the mask filters particles.

Question: The chapter argues that exact values are not always necessary during early scientific reasoning. What is the main justification given for this?
A. A rough estimate is often enough to judge whether an answer is reasonable or clearly impossible
B. Exact numbers are impossible to calculate in science
C. Scientists dislike using calculators
D. Estimation always gives the same result as exact calculation
Show Answer & Explanation

Answer: (A) A rough estimate is often enough to judge whether an answer is reasonable or clearly impossible

Explanation:
The point of estimating is not laziness but efficiency — a quick approximate check can immediately tell you if a result makes sense, long before you invest effort in getting a precise figure.

Question: Looking at how the chapter is organised, which idea is introduced before the discussion of laws, theories and principles?
A. The idea that science relies on precise symbols, units and mathematics to express relationships
B. The idea that predictions can fail and theories can be revised
C. The rice estimation activity for a family of four
D. The example of how a surgical mask works
Show Answer & Explanation

Answer: (A) The idea that science relies on precise symbols, units and mathematics to express relationships

Explanation:
The chapter first builds up the case for a shared scientific language of symbols and mathematics, and only after that does it move on to explaining how laws, theories and principles organise scientific understanding.

Question: The chapter points out that everyday words like force, work, cell and reaction carry very specific meanings in science. What does this reveal about scientific vocabulary?
A. Scientific terms are defined precisely so that ideas can be shared and compared without confusion anywhere in the world
B. Scientists prefer complicated words to sound impressive
C. These words mean the same thing in science as they do in daily conversation
D. Scientific vocabulary changes randomly from one country to another
Show Answer & Explanation

Answer: (A) Scientific terms are defined precisely so that ideas can be shared and compared without confusion anywhere in the world

Explanation:
Precision in language lets researchers everywhere describe the same observation the same way, which is essential when results need to be compared or built upon across different labs and countries.

Question: Why does the chapter insist that leaving out certain details while building a model is not a mistake?
A. Because ignoring irrelevant details keeps the model simple enough while still allowing the specific question to be answered
B. Because scientists are too lazy to include every detail
C. Because complete models are always wrong
D. Because ignoring details makes the model more expensive to test
Show Answer & Explanation

Answer: (A) Because ignoring irrelevant details keeps the model simple enough while still allowing the specific question to be answered

Explanation:
Every model is a deliberate trade-off. Details that do not affect the outcome being studied are dropped on purpose, not by accident, so the model stays useful without becoming impossibly complicated.

Question: What is the broader idea the chapter is trying to convey through its title, 'Exploration: Entering the World of Secondary Science'?
A. That secondary science is about learning how knowledge is built through observation, models, mathematics and testing, not just memorising facts
B. That secondary science mainly consists of memorising more formulas than before
C. That exploration means wandering without any particular direction
D. That science at this stage is entirely separate from what was studied earlier
Show Answer & Explanation

Answer: (A) That secondary science is about learning how knowledge is built through observation, models, mathematics and testing, not just memorising facts

Explanation:
Right from its opening lines, the chapter frames this stage of learning as a shift toward understanding 'how we know' things in science, using careful observation, symbolic language and testing, rather than just accumulating more information.

Question: Based on the chapter's description, how is a scientific model best defined?
A. A simplified representation of a real system that focuses only on details relevant to the question being asked
B. An exact, complete copy of a real system with nothing left out
C. A guess made without any supporting evidence
D. A fixed rule that never changes once written down
Show Answer & Explanation

Answer: (A) A simplified representation of a real system that focuses only on details relevant to the question being asked

Explanation:
This is the working definition used throughout the chapter, whether it is a car reduced to a point, a cell reduced to a diagram, or the Earth reduced to a smooth layered sphere.

Question: Why does the chapter include real-world 'Ready to Go Beyond' examples such as the aircraft fuel mishap, the rice estimation problem, and the mask design question?
A. To show that scientific thinking and estimation are useful tools for making sense of everyday, practical situations, not just classroom problems
B. To prove that science textbooks must always include aviation stories
C. To test whether students can memorise historical incidents
D. To demonstrate that real-world problems have no connection to science
Show Answer & Explanation

Answer: (A) To show that scientific thinking and estimation are useful tools for making sense of everyday, practical situations, not just classroom problems

Explanation:
These boxes take scientific habits like careful unit use, estimation, and cross-disciplinary thinking out of the textbook and into situations students can recognise from daily life, reinforcing that science is a way of reasoning about the real world.

Question: In the airplane fuel mishap described in the chapter, how much fuel did the flight actually require in total before it took off?
A. 22,300 kg
B. 15,000 kg
C. 2,230 kg
D. 150,000 kg
Show Answer & Explanation

Answer: (A) 22,300 kg

Explanation:
The chapter states the flight needed 22,300 kg of fuel, but ground crew miscalculated it using pounds instead of kilograms, leaving the plane roughly 15,000 litres short mid-air.

Question: The chapter uses climbing a staircase as an example while explaining a certain organising term in science. Which term does this illustrate?
A. A principle
B. A hypothesis
C. A unit
D. A variable
Show Answer & Explanation

Answer: (A) A principle

Explanation:
Climbing stairs is given as an everyday case where the principle of conservation of energy applies, showing how principles are broad ideas useful across many situations rather than narrow rules tied to one experiment.

Question: In the rice-estimation example, what daily calorie range is assumed for an average adult while working out how much rice a family would need in a month?
A. 2000 to 2500 kilocalories
B. 500 to 800 kilocalories
C. 5000 to 6000 kilocalories
D. 1000 to 1200 kilocalories
Show Answer & Explanation

Answer: (A) 2000 to 2500 kilocalories

Explanation:
This figure of 2000-2500 kcal per day is the starting point used to build a rough estimate, since the whole exercise assumes (for simplicity) that all of a person's energy comes from rice alone.

Question: While modelling the cricket shot, which factors does the chapter mention as having only a small effect that can be safely left out of a simple model?
A. Air resistance, ball spin, and seam stitching
B. The mass of the ball and its speed
C. The direction in which the ball was hit
D. Whether the ball clears the boundary
Show Answer & Explanation

Answer: (A) Air resistance, ball spin, and seam stitching

Explanation:
These are described as small, secondary effects — unlike the bat's brand or the ball's colour, which are irrelevant, air resistance, spin, and seam stitching do matter slightly but can be ignored in a basic model and added back only for greater accuracy.

Question: What is the purpose of the 'Next Level Up' boxes mentioned toward the end of the chapter?
A. To preview interesting topics from physics, chemistry, biology and earth science that students may study later
B. To list formulas students must memorise for exams
C. To summarise the previous chapter's key terms
D. To describe historical scientific instruments
Show Answer & Explanation

Answer: (A) To preview interesting topics from physics, chemistry, biology and earth science that students may study later

Explanation:
These boxes are meant to give a glimpse of exciting ideas waiting in the different branches of science, even though the chapter also reminds readers that nature itself does not respect these subject boundaries.

Question: Near its conclusion, the chapter describes science as a human activity. Which set of qualities does it say drives this activity forward?
A. Curiosity, creativity, collaboration, and careful questioning
B. Memorisation, repetition, and speed
C. Competition, secrecy, and individual credit
D. Funding, publishing, and patenting
Show Answer & Explanation

Answer: (A) Curiosity, creativity, collaboration, and careful questioning

Explanation:
Science grows because people keep asking questions, testing ideas, sharing results and learning from mistakes — the chapter frames this as a shared human pursuit rather than a fixed body of facts.

Question: In the Pause and Ponder activity asking students to sketch a pressure cooker, a mobile phone, or a traffic jam, what is the main skill being encouraged?
A. Recognising how ideas from more than one branch of science combine to explain a single real-world example
B. Memorising the parts of a machine in correct order
C. Calculating the exact cost of household appliances
D. Drawing accurate technical diagrams
Show Answer & Explanation

Answer: (A) Recognising how ideas from more than one branch of science combine to explain a single real-world example

Explanation:
This activity pushes students to notice, for instance, how physics and chemistry might both be needed to explain something as ordinary as a pressure cooker, reinforcing the chapter's point that real problems rarely fit inside one subject.

Question: The chapter organises extra content into two differently labelled boxes. Which topic appears specifically as a 'Threads of Curiosity' box rather than a 'Ready to Go Beyond' box?
A. Why the speed of light is denoted by the letter c
B. The airplane that ran out of fuel due to a unit mix-up
C. Estimating how much rice feeds a family for a month
D. Why weather forecasts sometimes go wrong
Show Answer & Explanation

Answer: (A) Why the speed of light is denoted by the letter c

Explanation:
The story behind the symbol c, taken from the Latin word celeritas, sits under a Threads of Curiosity heading, while the fuel mishap, the rice estimate, and the weather-forecast question are all presented as Ready to Go Beyond boxes.
• Threads of Curiosity boxes tend to explain naming or convention
• Ready to Go Beyond boxes tend to pose open-ended real-world puzzles

Question: What is the underlying point of the bicycle-ride activity, where students model the time taken to travel from school to home?
A. That leaving out unimportant details can make a model easier to use without ruining its usefulness
B. That travelling by bicycle is scientifically more efficient than walking
C. That every possible factor affecting the ride must be included for accuracy
D. That models are only useful in physics and not in daily-life situations
Show Answer & Explanation

Answer: (A) That leaving out unimportant details can make a model easier to use without ruining its usefulness

Explanation:
By asking students which details to keep and which to drop, the activity mirrors the cricket-shot example earlier in the chapter, driving home the idea that a good model keeps only what matters for the question being asked.

Question: Based on the balloon-filling method used to estimate daily breathing, roughly what volume was assigned to a single human breath?
A. About 0.5 litre
B. About 5 litres
C. About 20 litres
D. About 0.05 litre
Show Answer & Explanation

Answer: (A) About 0.5 litre

Explanation:
Since it takes about 4-5 breaths to inflate a 2-litre party balloon, one breath works out to roughly half a litre, a figure then multiplied by the estimated number of daily breaths to reach the final estimate.

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Chapter 02 Cell The Building Block Of Life Objective Questions & Solutions for Class 9 Science

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