Medium Human Body Quiz Questions for Kids (with Answers)
Use this printable quiz list for classroom warm-ups, car trips, or revision. Tap any question to reveal the answer and a short explanation — then play the full human body quiz online with hints and stars.
Questions & answers
Tap a question to reveal the answer. 35 questions below.
1. How many neurons does the human brain contain?Show answer
- About 10 million
- About 100 million
- About 86 billion — correct
- About 1 trillion
The human brain contains approximately 86 billion neurons — each connected to thousands of others!
🧠 The number of connections in your brain is greater than the number of stars in the Milky Way galaxy!
2. What is the name of the process by which your body converts food into energy?Show answer
- Photosynthesis
- Digestion
- Metabolism — correct
- Respiration
Metabolism is the set of chemical processes that convert food into energy your body can use!
⚡ Your metabolism never stops — even when you sleep your body burns calories to keep your heart beating and brain working!
3. Which part of the brain controls balance and coordination?Show answer
- Cerebrum
- Cerebellum — correct
- Brainstem
- Hippocampus
The cerebellum coordinates movement and balance — it receives signals from your eyes, ears and muscles!
🧠 Despite being only about 10% of the brain's volume the cerebellum contains more than half of all the brain's neurons!
4. How long are all the blood vessels in the human body if stretched out?Show answer
- 5,000 km
- 25,000 km
- 100,000 km — correct
- 500,000 km
All your blood vessels stretched out would be about 100,000 km — enough to circle the Earth 2.5 times!
🩸 The tiny capillaries in your body are so small that red blood cells must travel through them in single file!
5. Your body replaces most of its cells every 7 to 10 years.Show answer
Answer: True
Most of your body's cells are replaced regularly — skin cells every few weeks, red blood cells every 4 months, and so on!
🧠 However some neurons in your brain last your entire lifetime — you were born with them and they never get replaced!
6. What is the name of the body's main artery that carries blood from the heart?Show answer
- Jugular vein
- Pulmonary artery
- Aorta — correct
- Vena cava
The aorta is the largest artery in the body — it carries oxygen-rich blood from the left ventricle of the heart to the rest of the body!
🩸 The aorta is about as wide as a garden hose — about 2 to 3 centimetres in diameter!
7. Which part of the brain is responsible for memory and learning?Show answer
- Amygdala
- Hippocampus — correct
- Thalamus
- Cortex
The hippocampus is crucial for forming new memories and spatial navigation — its name means seahorse in Greek because of its shape!
🚕 Studies of London taxi drivers showed their hippocampus grew larger from memorising thousands of streets — proving the brain can physically change with learning!
8. How much of your immune system is located in your gut?Show answer
- About 20%
- About 40%
- About 70% — correct
- About 90%
About 70% of your immune system is located in your gut — the trillions of bacteria there play a crucial role in immunity!
🦠 Your gut contains about 38 trillion bacteria — roughly equal to the total number of human cells in your body!
9. The human eye can distinguish about 10 million different colours.Show answer
Answer: True
The human eye can distinguish approximately 10 million different colours thanks to three types of colour receptors called cones!
👁️ Some women have four types of colour receptors instead of three — they can potentially see up to 100 million different colours!
10. What is the name of the protein that makes blood red?Show answer
- Keratin
- Collagen
- Haemoglobin — correct
- Myosin
Haemoglobin is the protein in red blood cells that binds to oxygen and carries it around your body — the iron in it makes blood red!
🩸 Each red blood cell contains about 270 million haemoglobin molecules — each one can carry 4 oxygen molecules!
11. How many times does the average person blink per day?Show answer
- About 2,000
- About 7,000
- About 15,000 — correct
- About 25,000
The average person blinks about 15,000 to 20,000 times per day — about 10 to 15 times per minute!
👁️ Blinking keeps your eyes moist and clear — if you stopped blinking your eyes would dry out and you would go blind!
12. What is the name of the chemical that makes you feel happy?Show answer
- Adrenaline
- Cortisol
- Dopamine — correct
- Melatonin
Dopamine is a neurotransmitter that creates feelings of pleasure and reward — it motivates you to repeat enjoyable activities!
😊 Achieving goals — even small ones — releases dopamine! That is why ticking off a to-do list feels so satisfying!
13. Humans share about 60% of their DNA with bananas.Show answer
Answer: True
Humans share about 60% of their DNA with bananas — because all living things use the same basic genetic machinery!
🧬 Humans share 98.7% of DNA with chimpanzees and about 85% with mice — showing how closely related life on Earth is!
14. What is the name of the fluid that surrounds and protects your brain?Show answer
- Synovial fluid
- Lymph fluid
- Cerebrospinal fluid — correct
- Plasma
Cerebrospinal fluid surrounds your brain and spinal cord acting as a shock absorber and removing waste products!
🧠 Your body completely replaces its cerebrospinal fluid about 4 times per day — the old fluid is absorbed into the blood!
15. Which organ produces adrenaline?Show answer
- Thyroid gland
- Pituitary gland
- Adrenal glands — correct
- Pancreas
The adrenal glands sit on top of your kidneys and produce adrenaline which prepares your body for danger!
⚡ Adrenaline can give you superhuman strength in extreme situations — there are documented cases of people lifting cars to save lives!
16. How fast can nerve impulses travel in the human body?Show answer
- About 1 km/h
- About 30 km/h
- About 430 km/h — correct
- About 3000 km/h
The fastest nerve impulses travel at about 430 km/h — allowing your brain to react almost instantly to stimuli!
⚡ Pain signals travel more slowly than touch signals — that is why you feel the touch of something sharp before you feel the pain!
17. The human body generates enough heat in 30 minutes to boil a litre of water.Show answer
Answer: True
Your body generates significant heat as a byproduct of metabolism — in 30 minutes it produces enough to boil about half a litre of water!
🌡️ Your normal body temperature is 37°C — your body works constantly to maintain this exact temperature!
18. What is the name of the valve that prevents food from entering the lungs when you swallow?Show answer
- Trachea
- Epiglottis — correct
- Uvula
- Larynx
The epiglottis is a flap of cartilage that covers your windpipe when you swallow to prevent food from entering your lungs!
😂 When food goes down the wrong way it has passed your epiglottis into the trachea — coughing is your body's emergency response to clear it!
19. How many taste buds does the average human tongue have?Show answer
- About 500
- About 2,000
- About 10,000 — correct
- About 50,000
The average human tongue has about 10,000 taste buds — each one contains 50 to 150 receptor cells!
👅 Taste buds are not only on your tongue — you also have them on the roof of your mouth and in your throat!
20. What percentage of the human genome do all humans share?Show answer
- About 85%
- About 93%
- About 99.9% — correct
- About 100%
All humans share 99.9% of their DNA — the 0.1% difference accounts for all the variation in appearance, health and traits!
🧬 That tiny 0.1% difference amounts to about 3 million base pairs of DNA — enough to make each person completely unique!
21. Your stomach acid is strong enough to dissolve metal.Show answer
Answer: True
Stomach acid has a pH of 1 to 2 — strong enough to dissolve zinc and even some forms of iron!
🛡️ Your stomach lining produces a protective mucus layer to prevent the acid from digesting the stomach itself!
22. What is the name of the pigment that makes your hair black or brown?Show answer
- Keratin
- Melanin — correct
- Collagen
- Carotene
Melanin gives hair its colour — more eumelanin makes hair darker, more pheomelanin makes it red or blonde!
👴 Hair turns grey or white as you age because hair follicles gradually stop producing melanin!
23. How much saliva does your mouth produce each day?Show answer
- About 0.5 litres
- About 1.5 litres — correct
- About 3 litres
- About 5 litres
Your salivary glands produce about 1.5 litres of saliva every day — enough to fill 2 large glasses!
🦷 Saliva contains enzymes that start digesting your food before you even swallow — it also contains antibacterial compounds that protect your teeth!
24. What is the name of the tiny air sacs in the lungs where gas exchange occurs?Show answer
- Bronchi
- Capillaries
- Alveoli — correct
- Bronchioles
Alveoli are tiny air sacs in the lungs where oxygen enters the blood and carbon dioxide leaves — you have about 480 million of them!
🫁 If all your alveoli were spread flat they would cover an area the size of a tennis court!
25. Humans are the only animals that cry emotional tears.Show answer
Answer: True
While all mammals produce tears for lubrication crying as an emotional response appears to be uniquely human!
😢 Emotional tears contain stress hormones — some scientists believe crying actually helps your body remove these chemicals and feel better!
26. What is the medical term for your collarbone?Show answer
- Scapula
- Sternum
- Clavicle — correct
- Coracoid
The clavicle or collarbone connects your shoulder blade to your breastbone and is one of the most frequently broken bones in the body!
🦴 The clavicle is the only long bone in the body that lies horizontally — and it is often the first bone to break in a fall because we instinctively reach out our arms!
27. How many words can the average person speak per minute?Show answer
- About 80
- About 130 — correct
- About 200
- About 300
The average person speaks about 130 words per minute in conversation — though some people can speak over 300 words per minute!
🗣️ The fastest talkers in the world can speak over 600 words per minute — but they become very hard to understand!
28. What is the function of platelets in your blood?Show answer
- Carry oxygen
- Fight infection
- Form blood clots — correct
- Produce hormones
Platelets are tiny blood cells that clump together at a wound site to form a clot and stop bleeding!
🩸 A single drop of blood contains about 15 million platelets — your body produces about 100 billion new platelets every day!
29. Your brain shrinks slightly as you age.Show answer
Answer: True
The brain does slowly shrink from about age 30 to 40 — it loses about 5% of its volume per decade after 40!
🧠 Regular exercise mental stimulation and social interaction can slow brain shrinkage — another reason to stay active and keep learning!
30. What is the name of the hormone that regulates sleep?Show answer
- Serotonin
- Cortisol
- Melatonin — correct
- Dopamine
Melatonin is produced by the pineal gland in your brain — levels rise at night to make you sleepy and fall in the morning to wake you up!
📱 Blue light from phone screens suppresses melatonin production — that is why using your phone before bed makes it harder to fall asleep!
31. How much does the human brain weigh on average?Show answer
- About 0.5 kg
- About 1.4 kg — correct
- About 2.5 kg
- About 4 kg
The average adult human brain weighs about 1.4 kg — roughly 2% of body weight but uses 20% of energy!
🧠 Albert Einstein's brain weighed 1.23 kg — slightly below average — but had an unusually large inferior parietal lobe associated with mathematical thinking!
32. What is the name of the transparent layer at the front of the eye?Show answer
- Retina
- Iris
- Cornea — correct
- Sclera
The cornea is the transparent dome covering the front of your eye — it provides about 65% of your eye's focusing power!
👁️ The cornea is the only tissue in the body with no blood vessels — it gets oxygen directly from the air through tears!
33. You lose about 50 to 100 hairs per day naturally.Show answer
Answer: True
Losing 50 to 100 hairs per day is completely normal — each hair goes through a growth cycle of growing resting and shedding!
💇 You have about 100,000 hairs on your head — at 100 per day loss it would take about 1,000 days to lose them all if they weren't replaced!
34. What is the name of the largest vein in the human body?Show answer
- Aorta
- Jugular vein
- Vena cava — correct
- Pulmonary vein
The vena cava is the largest vein in the body — it carries deoxygenated blood from the body back to the right side of the heart!
🩸 There are actually two vena cavae — the superior carries blood from the upper body and the inferior from the lower body!
35. How many times does your heart beat in an average lifetime?Show answer
- About 500 million
- About 1 billion
- About 2.5 billion — correct
- About 5 billion
Over an average lifetime of 80 years your heart beats approximately 2.5 billion times — without ever stopping to rest!
❤️ The heart is so good at its job that it can keep beating even when removed from the body as long as it has an oxygen supply!
Medium Human Body Quiz Questions for Kids (with Answers)