Bones, brains, sleep and how your body works.
About this quiz
This Human Body Quiz is about the everyday mysteries of your own body: why your recorded voice sounds strange to you, when in the day you are tallest, what the funny bone really is and how ears keep themselves clean. It covers the senses, the brain, the heart, sleep and hunger, with a few things you can try out on yourself.
Some questions go further, into how babies develop before birth and the anatomists and scientists behind landmark discoveries about the body. Every round has 10 questions on a 20-second timer, and the short explanation after each answer is where most of the surprises are.
Try a few questions
Tap an answer to check it, or open the answer underneath.
Why does your own voice sound deeper to you than it does on a recording?
- Microphones cannot record low notes
- You also hear it through the bones of your skull
- Air inside your mouth muffles the high notes
- Your ears are tuned to ignore your own voice
Answer: You also hear it through the bones of your skull
Did you know? Everyone else hears your voice only through the air, but you also hear it as vibrations conducted through your jaw and skull, which carry the lower frequencies particularly well. A recording strips out that bone-conducted bass, which is why the played-back voice sounds thin and unfamiliar — that is what you actually sound like to others.
Most ear canals keep themselves clean without any help. How do they do it?
- Tiny hairs beat in waves to sweep wax out
- Their skin lining creeps slowly outwards
- The wax dissolves itself every few days
- The eardrum's vibrations shake dirt loose
Answer: Their skin lining creeps slowly outwards
Did you know? Skin cells grow outwards from the centre of the eardrum and then along the canal walls, carrying wax and dust towards the opening like a conveyor belt, while chewing and talking help to shake it loose. In ink-dot experiments of 1964, the skin was found to move about 0.05 mm a day.
You are measurably taller at one time of day than another. When are you tallest?
- At midday
- Height never changes
- In the morning
- In the evening
Answer: In the morning
Did you know? Overnight, the soft discs between your vertebrae soak up fluid and plump back up, so you can be up to a centimetre taller when you wake. A day of standing gently squashes them again.
Shine a torch into just one of someone's eyes. What does the pupil of the other, unlit eye do?
- Narrows as well
- Stays exactly the same
- Widens to compensate
- Twitches from side to side
Answer: Narrows as well
Did you know? Light falling on one retina sends signals to both sides of the brainstem, which tell both irises to tighten together. This is called the consensual light reflex. A pupil can shrink to about 2 millimetres in bright light and open to as much as 8 millimetres in the dark.