Class 3 Science Olympiad Practice Paper

 

Class 3 Science Olympiad practice paper-1 with 30 MCQs covering plants, animals, human body, food, materials, force, light, and space  plus a full answer key with explanations.

 

Section A: Plants & Animals (Q1–Q10)

Q1. Which part of the plant takes in water and minerals from the soil?

(A) Leaf     (B) Root     (C) Stem     (D) Flower

 

Q2. Seeds of which plant are dispersed by wind because of their light, feathery structure?

(A) Mango     (B) Dandelion     (C) Coconut     (D) Pea

 

Q3. A plant kept inside a dark cupboard for two weeks turns pale yellow. What is the most likely reason?

(A) Lack of water     (B) Lack of sunlight     (C) Too much water     (D) Lack of soil

 

Q4. Which of these is NOT a function of leaves?

(A) Making food     (B) Releasing oxygen     (C) Absorbing minerals from soil     (D) Transpiration (losing water vapour)

 

Q5. Camels store fat in their hump. This mainly helps them to:

(A) Swim faster     (B) Survive without food or water for long periods     (C) See better in the dark     (D) Run faster on sand

 

Q6. Which of these animals is a mammal even though it lives in water?

(A) Shark     (B) Dolphin     (C) Octopus     (D) Jellyfish

 

Q7. Animals that eat both plants and other animals are called:

(A) Herbivores     (B) Carnivores     (C) Omnivores     (D) Decomposers

 

Q8. Which of the following undergoes complete metamorphosis (egg → larva → pupa → adult)?

(A) Grasshopper     (B) Butterfly     (C) Cockroach     (D) Dragonfly

 

Q9. A group of lions living together is called a:

(A) Herd     (B) Pride     (C) Flock     (D) Pack

 

Q10. Which bird cannot fly but is an excellent swimmer, found mostly in cold regions?

(A) Ostrich     (B) Penguin     (C) Peacock     (D) Kiwi

 

Section B: Human Body & Food (Q11–Q20)

 

Q11. Which organ pumps blood to all parts of the body?

(A) Lungs     (B) Brain     (C) Heart     (D) Kidney

 

Q12. The gases we breathe IN and breathe OUT in larger amounts are, respectively:

(A) Oxygen, Nitrogen     (B) Oxygen, Carbon dioxide     (C) Carbon dioxide, Oxygen     (D) Nitrogen, Oxygen

 

Q13. Riya touches an ice cube and quickly pulls her hand back, saying, “It’s too cold!” Which sense organ helped her feel this?

(A) Eyes     (B) Nose     (C) Skin     (D) Tongue

 

Q14. Which of these food items is the richest source of protein?

(A) Rice     (B) Sugar     (C) Pulses (dal)     (D) Butter

 

Q15. Milk teeth in humans eventually fall out and are replaced by:

(A) Wisdom teeth     (B) Permanent teeth     (C) No new teeth grow     (D) Baby teeth grow back

 

Q16. Which vitamin do we mainly get from sunlight, and which is essential for strong bones?

(A) Vitamin A     (B) Vitamin C     (C) Vitamin D     (D) Vitamin K

 

Q17. The smallest bone in the human body is found in the:

(A) Finger     (B) Ear     (C) Nose     (D) Toe

 

Q18. Why do we need to chew food properly before swallowing it?

(A) To make it colorful     (B) To break it into smaller pieces for easy digestion     (C) To make it cold     (D) To add air to it

 

Q19. Which disease commonly spreads through the bite of an infected mosquito?

(A) Diabetes     (B) Malaria     (C) Asthma     (D) Arthritis

 

Q20. After playing outside on a hot day, Aman feels thirsty and his skin becomes sweaty. This is mainly the body’s way of:

(A) Cooling down and maintaining water balance     (B) Making him hungry     (C) Helping him sleep     (D) Making him taller

 

Section C: Materials, Force, Light, Water, Air & Space (Q21–Q30)

 

Q21. Which of these materials is a good conductor of heat?

(A) Wood     (B) Plastic     (C) Iron     (D) Rubber

 

Q22. Which of these objects will most likely float on water?

(A) Iron nail     (B) Stone     (C) An empty, closed plastic bottle     (D) Coin

 

Q23. The process by which water changes into water vapour is called:

(A) Condensation     (B) Evaporation     (C) Precipitation     (D) Freezing

 

Q24. Which of these is NOT a source of light?

(A) Sun     (B) Candle     (C) Moon     (D) Bulb

 

Q25. A shadow is formed when:

(A) Light passes completely through an object     (B) An opaque object blocks the path of light     (C) Light bends around an object     (D) Sound waves are blocked

 

Q26. Which force pulls all objects towards the ground?

(A) Magnetic force     (B) Gravitational force     (C) Muscular force     (D) Frictional force

 

Q27. A ball rolling on the ground eventually slows down and stops. Which force is mainly responsible for this?

(A) Gravity     (B) Friction     (C) Magnetism     (D) Push

 

Q28. Which of these is a renewable source of energy?

(A) Coal     (B) Petrol     (C) Sunlight     (D) Natural gas

 

Q29. The Earth takes approximately how long to complete one full spin on its axis?

(A) 1 hour     (B) 24 hours     (C) 1 month     (D) 1 year

 

Q30. If the Moon appears as a thin, curved shape in the night sky, this shape is called a:

(A) Full moon     (B) New moon     (C) Crescent moon     (D) Half moon

 

 

Answer Key & Explanations

Q#	Ans	Explanation
1	B	Root — Roots have tiny root hairs that absorb water and minerals from the soil and anchor the plant firmly.
2	B	Dandelion — Dandelion seeds have a fluffy, parachute-like structure that lets the wind carry them far away.
3	B	Lack of sunlight — Without sunlight, a plant cannot make chlorophyll (the green pigment), so its leaves turn pale yellow.
4	C	Absorbing minerals from soil — Absorbing minerals from the soil is the job of the roots, not the leaves.
5	B	Survive without food or water for long periods — The fat stored in the hump can be broken down for energy and water, helping camels survive long desert journeys.
6	B	Dolphin — Dolphins breathe air through lungs and feed their young milk, which makes them mammals, unlike fish.
7	C	Omnivores — Omnivores, such as bears and humans, eat a mixed diet of both plant and animal food.
8	B	Butterfly — A butterfly changes completely through four stages, including a resting pupa (chrysalis) stage.
9	B	Pride — A group of lions is called a ‘pride’, while wolves form ‘packs’ and sheep form ‘herds’.
10	B	Penguin — Penguins have flipper-like wings suited for swimming, not flying, and are adapted to cold climates.
11	C	Heart — The heart continuously pumps blood through blood vessels to every part of the body.
12	B	Oxygen, Carbon dioxide — We inhale air rich in oxygen and exhale air with more carbon dioxide, produced when our body uses oxygen.
13	C	Skin — The skin contains nerve endings that detect touch, temperature, and pain.
14	C	Pulses (dal) — Pulses like dal are rich in protein, which helps in the growth and repair of our body.
15	B	Permanent teeth — Milk (temporary) teeth are naturally replaced by permanent teeth as a child grows older.
16	C	Vitamin D — Our skin produces Vitamin D when exposed to sunlight, and it helps the body absorb calcium for strong bones.
17	B	Ear — The stapes, the smallest bone in the human body, is located in the middle ear.
18	B	To break it into smaller pieces for easy digestion — Chewing breaks food into smaller pieces and mixes it with saliva, making it easier for the stomach to digest.
19	B	Malaria — Malaria is caused by a parasite that spreads to humans through the bite of infected female Anopheles mosquitoes.
20	A	Cooling down and maintaining water balance — Sweating helps cool the body down, and thirst signals the body to replace the water lost.
21	C	Iron — Metals like iron allow heat to pass through them easily, which is why cooking utensils are often made of metal.
22	C	An empty, closed plastic bottle — An empty, closed plastic bottle is filled mostly with air and is light for its size, so it floats easily.
23	B	Evaporation — Evaporation is the process where liquid water absorbs heat and changes into water vapour.
24	C	Moon — The Moon does not produce its own light; it only reflects sunlight falling on it.
25	B	An opaque object blocks the path of light — Opaque objects do not let light pass through them, so they block light and form a dark shadow behind them.
26	B	Gravitational force — The Earth’s gravitational force pulls every object towards its centre, which is why things fall downward.
27	B	Friction — Friction between the ball and the ground opposes its motion, gradually slowing it down until it stops.
28	C	Sunlight — Sunlight is available in unlimited supply every day and does not get used up, unlike coal or petrol.
29	B	24 hours — One complete rotation of the Earth on its axis takes about 24 hours, giving us day and night.
30	C	Crescent moon — A thin, curved sliver of the Moon that we see is called a crescent moon, one of the phases of the Moon.