Hard 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. 25 questions below.
1. What is the name of the process by which cells divide to create exact copies?Show answer
- Meiosis
- Mitosis — correct
- Osmosis
- Photosynthesis
Mitosis is cell division that produces two identical daughter cells — it is how your body grows repairs and replaces cells!
🔬 Your body undergoes about 25 million cell divisions every second through mitosis!
2. What is the name of the enzyme in saliva that begins carbohydrate digestion?Show answer
- Pepsin
- Lipase
- Amylase — correct
- Protease
Salivary amylase begins breaking down carbohydrates in your mouth before food even reaches your stomach!
🍞 If you hold a plain cracker in your mouth long enough it will start to taste sweet — amylase is converting the starch to sugar!
3. How many base pairs of DNA are in the human genome?Show answer
- About 300 million
- About 1 billion
- About 3 billion — correct
- About 30 billion
The human genome contains about 3 billion base pairs of DNA — encoding approximately 20,000 to 25,000 genes!
📚 If you typed out all your DNA it would fill about 1.5 million pages of text — or take 9.5 years to read aloud non-stop!
4. What is the name of the neurotransmitter that is deficient in Parkinson's disease?Show answer
- Serotonin
- Acetylcholine
- Dopamine — correct
- GABA
Parkinson's disease is caused by the loss of dopamine-producing neurons in the brain affecting movement and coordination!
🧠 The substantia nigra region of the brain — which produces dopamine — gets its name from its dark colour caused by the neuromelanin in dopamine neurons!
5. What is the name of the structure that connects muscle to bone?Show answer
- Ligament
- Cartilage
- Tendon — correct
- Fascia
Tendons connect muscles to bones — the Achilles tendon connecting your calf muscle to your heel is the largest in the body!
🏃 The Achilles tendon can withstand forces up to 12 times your body weight during running — making it one of the strongest tendons!
6. What is the normal pH of human blood?Show answer
- About 5.5
- About 6.8
- About 7.4 — correct
- About 8.2
Human blood has a pH of about 7.35 to 7.45 — slightly alkaline. Even small changes can be life threatening!
🩸 Your body has multiple systems to maintain blood pH — if it drops below 7.35 you have acidosis which is a medical emergency!
7. Which part of the brain is responsible for processing emotions?Show answer
- Hippocampus
- Amygdala — correct
- Thalamus
- Hypothalamus
The amygdala processes emotions especially fear and pleasure — it also plays a role in memory formation for emotional events!
😱 The amygdala can trigger a fear response before you are even consciously aware of the threat — it is your brain's alarm system!
8. What is the name of the protein that makes skin elastic?Show answer
- Keratin
- Melanin
- Elastin — correct
- Collagen
Elastin is the protein that gives skin its elasticity — it allows skin to stretch and spring back. Production decreases with age causing wrinkles!
🧴 Elastin fibres can be stretched to 150% of their length and still return to their original size — that is more elastic than a rubber band!
9. What is the name of the involuntary muscle movement that pushes food through your digestive system?Show answer
- Peristalsis — correct
- Osmosis
- Diffusion
- Absorption
Peristalsis is the wave-like muscle contractions that move food through your digestive system — it works even upside down!
🚀 Astronauts can eat and drink normally in space because peristalsis works regardless of gravity — not suction or gravity as many people think!
10. What is the name of the condition where the immune system attacks the body's own cells?Show answer
- Immunodeficiency
- Allergy
- Autoimmune disease — correct
- Inflammation
Autoimmune diseases occur when the immune system mistakenly attacks healthy cells — there are over 80 known autoimmune conditions!
🔬 About 1 in 13 people worldwide suffer from an autoimmune disease and women are about three times more likely to develop one than men!
11. What is the approximate surface area of the human small intestine?Show answer
- About 2 square metres
- About 10 square metres
- About 32 square metres — correct
- About 100 square metres
The small intestine has a surface area of about 32 square metres — the size of a small studio flat — due to millions of tiny villi!
🌀 The villi in your small intestine have even tinier microvilli on them called the brush border — together they maximise nutrient absorption!
12. The human body has more bacterial cells than human cells.Show answer
Answer: True
Current estimates suggest the human body contains roughly equal numbers of bacterial and human cells — about 38 trillion of each — with bacteria possibly slightly outnumbering human cells!
🦠 The bacteria in your gut weigh about 1 to 2 kg — roughly the same as your brain — and play crucial roles in digestion immunity and even mental health!
13. What is the name of the protein that gives bones their flexibility?Show answer
- Calcium
- Keratin
- Collagen — correct
- Elastin
Collagen provides bones with flexibility and resilience — calcium makes them hard but collagen prevents them from shattering on impact!
🦴 Collagen is the most abundant protein in the human body making up about 30% of total protein — it is also found in skin tendons and cartilage!
14. What is the name of the chemical that transmits signals across synapses between neurons?Show answer
- Hormone
- Enzyme
- Neurotransmitter — correct
- Antibody
Neurotransmitters are chemicals that carry signals across the synaptic gap between neurons — they include dopamine serotonin and acetylcholine!
⚡ The gap between neurons at a synapse is only 20 to 40 nanometres wide — about 1,000 times thinner than a human hair!
15. What is the name of the layer of tissue that lines the inside of blood vessels?Show answer
- Epithelium
- Endothelium — correct
- Myocardium
- Periosteum
The endothelium is a single layer of cells lining all blood vessels — it controls blood clotting inflammation and passage of substances!
🩸 If you spread out all the endothelial cells in your body they would cover about 6 tennis courts!
16. What is the name of the part of the brain that regulates body temperature and hunger?Show answer
- Thalamus
- Hypothalamus — correct
- Cerebellum
- Medulla
The hypothalamus regulates body temperature hunger thirst sleep and hormone production — it is your body's master control centre!
🌡️ Your hypothalamus maintains your body temperature within a tiny range of 36.1 to 37.8°C regardless of whether you are in the Arctic or a desert!
17. Which cells in the eye are responsible for colour vision?Show answer
- Rods
- Cones — correct
- Bipolar cells
- Ganglion cells
Cone cells in the retina detect colour — there are three types detecting red green and blue light which combine to create all colours you see!
👁️ You have about 6 million cone cells but 120 million rod cells — rods are much more sensitive and work in dim light but cannot detect colour!
18. The human appendix has no known function.Show answer
Answer: False
The appendix may serve as a safe house for beneficial gut bacteria helping to repopulate the gut after illness — it is not completely without function!
🔬 The appendix is more common in mammals that eat plant material suggesting it may have played a role in digesting tough plant fibres in our ancestors!
19. What is the name of the process by which the body maintains a stable internal environment?Show answer
- Metabolism
- Homeostasis — correct
- Catabolism
- Anabolism
Homeostasis is the process by which the body maintains stable internal conditions despite changes in the external environment!
⚖️ Your body performs thousands of homeostatic adjustments every second — from adjusting blood pressure to controlling body temperature!
20. What is the name of the longest nerve in the human body?Show answer
- Femoral nerve
- Vagus nerve
- Sciatic nerve — correct
- Tibial nerve
The sciatic nerve is the longest nerve in the body running from the lower spine through the buttock and down each leg to the foot!
🦵 The sciatic nerve can be as wide as your thumb in some places — it is the widest nerve as well as the longest!
21. What percentage of oxygen does the brain use despite being only 2% of body weight?Show answer
- About 5%
- About 10%
- About 20% — correct
- About 40%
The brain uses about 20% of the body's oxygen and energy despite being only 2% of body weight — it is the most metabolically active organ!
🧠 Even during sleep your brain continues to use almost as much energy as when you are awake — it is never truly off!
22. What is the name of the type of joint found in your knee?Show answer
- Ball and socket joint
- Pivot joint
- Hinge joint — correct
- Saddle joint
The knee is a hinge joint allowing movement in one plane — bending and straightening like a door hinge!
🦵 Your hip is a ball and socket joint allowing movement in all directions — that is why you can swing your leg forward backward and sideways!
23. Your eyes are the same size from birth to adulthood.Show answer
Answer: False
Eyeballs do grow — they are about 16.5mm at birth reaching the adult size of about 24mm by early adulthood. However they grow much less proportionally than other organs!
👁️ Baby eyes look proportionally large because the eyeball grows less than the face — that is why babies have that wide-eyed appearance!
24. What is the name of the substance that coats nerve fibres to speed up signal transmission?Show answer
- Collagen
- Keratin
- Myelin — correct
- Elastin
Myelin is a fatty substance that wraps around nerve fibres like insulation on a wire — it speeds up nerve signals up to 100 times faster!
⚡ Multiple sclerosis is a disease where the immune system attacks myelin — this disrupts nerve signals causing the wide range of MS symptoms!
25. What is the name of the master gland that controls most other hormone-producing glands?Show answer
- Thyroid gland
- Adrenal gland
- Pituitary gland — correct
- Pineal gland
The pituitary gland is only the size of a pea but controls growth reproduction thyroid function and many other vital processes!
👑 The pituitary gland produces growth hormone — too much causes gigantism and too little causes dwarfism showing how powerful this tiny gland is!
Hard Human Body Quiz Questions for Kids (with Answers)