General Science MCQ Quiz 3 – Basic

If you’re preparing for TNPSC General Science, this quiz is a simple way to check how well you remember the basics. You’ll find questions covering important topics from Physics, Chemistry and Biology, just like the kind of facts you need to be comfortable with during exam preparation. Take this General Science MCQ Quiz 3 as a free online test and see how many you can answer without looking at the explanations. Once you finish, go through the explanations and additional information to understand the topics better and revise the important points for your TNPSC preparation.

Note: Detailed answer explanations are provided below the test to support your learning and help you prepare more confidently for TNPSC examinations.

Time’s up

General Science MCQ Quiz 3 – A Quick Look at the Topic

Finished the quiz? Don’t stop with checking the correct answers. The explanations below will help you understand why each answer is correct and make the important General Science topics easier to remember. Each question is followed by a clear explanation and some additional information so you can learn a little more instead of simply memorizing the answer. Use this section to review the questions you found difficult and strengthen your basics in Physics, Chemistry and Biology for TNPSC preparation.

Q1. The basic unit of life is:

Answer: Cell

Explanation

The cell is considered the basic structural and functional unit of life. All living organisms are made up of cells, and the cell is the smallest unit capable of carrying out essential life processes such as nutrition, respiration, growth, reproduction and removal of waste.

Organisms may consist of a single cell or many cells. Unicellular organisms, such as bacteria and Amoeba, perform all their life activities within one cell. Multicellular organisms, such as humans and plants, are made up of many specialized cells that work together to form tissues and organs.

Additional Information

• Cells were first observed and described by Robert Hooke in 1665 while examining thin slices of cork.
• Organisms may be unicellular or multicellular.
• A tissue is a group of similar cells performing a specific function.
• Organs are made up of different tissues working together.
• Cells are broadly classified into prokaryotic and eukaryotic cells.

Q2. Which organ helps in breathing?

Answer: Lungs

Explanation

The lungs are the main organs of the respiratory system and are responsible for the exchange of gases between the body and the atmosphere. During inhalation, air enters the lungs and oxygen passes from the air into the blood. At the same time, carbon dioxide produced by the body’s cells is transferred from the blood into the lungs and removed from the body during exhalation.

Inside the lungs, gas exchange mainly takes place in tiny air sacs called alveoli. Their thin walls and rich blood supply allow oxygen and carbon dioxide to move efficiently between the air and the blood.

Additional Information

• Humans have two lungs located in the chest cavity.
• The right lung is slightly larger than the left lung because the heart occupies space on the left side.
• Alveoli are the main sites of gaseous exchange in the lungs.
• The diaphragm is an important muscle that helps in breathing.
• Oxygen is transported from the lungs to body tissues mainly by haemoglobin in red blood cells.
• Carbon dioxide is carried back to the lungs and removed during exhalation.

Q3. Which vitamin helps in blood clotting?

Answer: Vitamin K

Explanation

Vitamin K is essential for normal blood clotting. It helps the liver produce several proteins known as clotting factors, which are involved in the process of forming a blood clot when a blood vessel is injured. Without sufficient vitamin K, the blood may take longer to clot, which can increase the risk of excessive bleeding.

Vitamin K is a fat-soluble vitamin and is obtained from the diet. Green leafy vegetables are important dietary sources, and certain bacteria in the intestine can also produce forms of vitamin K.

Additional Information

• Vitamin K is mainly associated with the normal blood-clotting process.
• Vitamin K₁ is also called phylloquinone and is commonly found in green leafy vegetables.
• Vitamin K₂ includes several forms called menaquinones.
• The liver uses vitamin K to produce several important clotting factors.
• Vitamin K also has a role in maintaining normal bone health.
• Severe vitamin K deficiency can interfere with normal blood clotting.

Q4. At standard atmospheric pressure, the boiling point of water is:

Answer: 100°C

Explanation

At standard atmospheric pressure, water boils at 100°C. Boiling occurs when the vapour pressure of water becomes equal to the pressure exerted by the surrounding atmosphere. At this temperature, water changes from its liquid state into water vapour.

The boiling point is affected by atmospheric pressure. At higher altitudes, atmospheric pressure is lower, so water boils at a temperature below 100°C. This is why the boiling point of water is not exactly the same everywhere.

Additional Information

• The standard boiling point of water is 100°C at 1 atmosphere of pressure.
• The same temperature is 373.15 K on the Kelvin scale.
• It is 212°F on the Fahrenheit scale.
• The boiling point decreases when atmospheric pressure decreases.
• Water boils at a lower temperature at high altitudes.
• A pressure cooker increases pressure inside the vessel, allowing water to reach a temperature above 100°C.

Q5. Which part of plant absorbs water?

Answer: Root

Explanation

The root is the main part of a plant responsible for absorbing water and mineral nutrients from the soil. Water enters the root mainly through tiny structures called root hairs, which provide a large surface area for absorption. From the root, water moves into the plant’s vascular tissue and is transported upward to the stem and leaves.

Water absorption is essential because plants need water for photosynthesis, transport of dissolved minerals, maintenance of cell structure and other physiological activities.

Additional Information

• Root hairs are extensions of specialised epidermal cells of the root.
• Water generally enters root hairs by osmosis because of differences in water concentration.
• The xylem transports absorbed water and minerals from the roots to the stem and leaves.
• Roots also anchor the plant firmly in the soil.
• Some roots, such as those of carrot and sweet potato, are modified for storing food.
• Root systems are broadly classified as taproot systems and fibrous root systems.

Q6. The hardest substance in the human body is:

Answer: Tooth enamel

Explanation

Tooth enamel is the hardest substance in the human body. It is the thin, outermost layer that covers the crown of a tooth and protects the underlying dentin and pulp from mechanical wear and damage. Enamel is extremely hard because it contains a very high proportion of mineral, mainly in the form of hydroxyapatite, a calcium phosphate compound.

Unlike bone, tooth enamel does not contain living cells and cannot naturally repair itself once it is significantly damaged. This is why maintaining good oral hygiene is important for preventing enamel erosion and tooth decay.

Additional Information

• Tooth enamel is composed mainly of minerals, particularly hydroxyapatite.
• Enamel protects the tooth from the forces involved in biting and chewing.
• Dentin lies beneath the enamel and is softer than enamel.
• Bone is strong and living tissue, but it is not as hard as tooth enamel.
• Enamel cannot regenerate naturally because it does not contain living cells.
• Fluoride can help strengthen tooth enamel and make it more resistant to acid attacks.

Q7. Electricity is measured using:

Answer: Ammeter

Explanation

An ammeter is an instrument used to measure electric current in a circuit. Electric current refers to the flow of electric charge through a conducting path, and its SI unit is the ampere (A). An ammeter is connected in series with the circuit so that the current flowing through the circuit passes through the instrument.

The term “electricity” can refer to several electrical quantities, so different instruments are used for different measurements. For example, a voltmeter measures potential difference, while an ammeter measures electric current.

Additional Information

• An ammeter measures electric current in amperes.
• The SI unit of electric current is ampere (A).
• An ammeter is connected in series in an electrical circuit.
• A voltmeter is used to measure potential difference or voltage.
• An ohmmeter is used to measure electrical resistance.
• A multimeter can measure several electrical quantities, including current, voltage and resistance.

Q8. Which gas is released during photosynthesis?

Answer: Oxygen

Explanation

Oxygen is released as a by-product during photosynthesis. Green plants use light energy to convert carbon dioxide and water into glucose. During this process, water molecules are split as part of the light-dependent reactions, and oxygen is released and eventually diffuses out of the leaf through the stomata.

The oxygen released by plants enters the atmosphere and becomes available for respiration in animals and other organisms. Photosynthesis therefore plays an important role in maintaining the oxygen supply in Earth’s atmosphere.

Additional Information

• Oxygen released during photosynthesis comes from water molecules, not directly from carbon dioxide.
• Carbon dioxide enters the leaf mainly through stomata.
• Chlorophyll absorbs the light energy required for photosynthesis.
• Glucose produced during photosynthesis stores chemical energy that the plant can use.
• Photosynthesis mainly occurs in the chloroplasts of green plant cells.
• Photosynthesis contributes to the continuous exchange of oxygen and carbon dioxide between living organisms and the atmosphere.

Q9. The centre of an atom is called:

Answer: Nucleus

Explanation

The nucleus is the small, dense central region of an atom. It contains positively charged protons and electrically neutral neutrons. Almost all of the mass of an atom is concentrated in the nucleus, while electrons occupy the space around it.

The number of protons in the nucleus determines the atomic number and therefore identifies the element. For example, every hydrogen atom has one proton, while every carbon atom has six protons.

Additional Information

• Protons have a positive electric charge.
• Neutrons have no electric charge.
• Electrons have a negative electric charge and are found outside the nucleus.
• The atomic number of an element is equal to the number of protons in its nucleus.
• The total number of protons and neutrons gives the mass number of an atom.
• Most of the volume of an atom is the space occupied by the electron cloud.

Q10. Sound travels fastest in:

Answer: Solid

Explanation

Sound is a mechanical wave, so it needs a material medium to travel. It moves through a medium by causing its particles to vibrate and transfer the disturbance from one particle to another. In general, sound travels fastest through solids because their particles are closely packed and the bonds between them allow vibrations to be transmitted efficiently.

Sound travels more slowly through liquids and even more slowly through gases. It cannot travel through a vacuum because there are no particles available to transmit the vibrations.

Additional Information

• Sound generally travels fastest in solids, followed by liquids and gases.
• Sound cannot travel through a vacuum.
• The speed of sound in air is approximately 343 m/s at 20°C.
• The speed of sound changes with the properties and temperature of the medium.
• Steel and other solids can transmit sound at speeds of several kilometres per second.
• Sound is a mechanical wave because it requires a medium for its propagation.

Quick Q&A Revision

• Basic unit of life? → Cell
• Organ for breathing? → Lungs
• Vitamin for clotting? → Vitamin K
• Boiling point measured in? → Celsius
• Water absorbed by? → Roots
• Hardest substance in body? → Enamel
• Electricity measured by? → Ammeter
• Gas released in photosynthesis? → Oxygen
• Centre of atom? → Nucleus
• Sound travels fastest in? → Solids

Quick Revision

Easy Memory Check

• Life → Cell
• Breathing → Lungs
• Blood clotting → Vitamin K
• Water boiling → 100°C
• Water absorption → Root
• Hardest body substance → Enamel
• Current → Ammeter
• Photosynthesis → Oxygen released
• Atom centre → Nucleus
• Sound fastest → Solid

Further Reading:

Want to explore these General Science topics in more detail? You can refer to the NCERT Science textbooks for clear explanations of fundamental concepts in Physics, Chemistry and Biology. Reading the relevant chapters can help you strengthen your basics, understand the concepts behind these MCQs and prepare more confidently for TNPSC General Science questions. The official NCERT textbooks are available online for different classes and subjects. For detailed science concepts and clear explanations, refer to the official NCERT Science textbooks available on the NCERT website:

👉 NCERT Official Website – 10th Science Textbooks

Keep practising General Science MCQ questions regularly to build a strong foundation for TNPSC preparation. Try this free online test again after revision and check whether you can improve your score. Practising science MCQ questions from Physics, Chemistry and Biology can help you become more confident with important General Science topics and prepare better for the TNPSC exam.