QandA

Q&A Tabs

Phlegm is the mucous secretion of the respiratory passages. The cilia cells that line these passages are continually driving the phlegm upward to the throat, where it triggers the swallow reflex...

Astronomer Fred Hoyle was the first to point out that if you could drive a car upwards at 95km/h (60mph), it would only take about an hour to get into space. To get to the Moon would take a little...

It is a widely held belief that cows and horses cannot walk down stairs. These animals can't easily see the ground right at their feet and the design of their hips and knees makes it hard to shift...

Mammals remove excess nitrogen from their bodies by converting it to a dilute solution of urea, stored in the bladder. Birds convert nitrogen to uric acid instead: this is metabolically more...

The strongest teeth are natural, healthy ones and these teeth are not white. At least, not white like the colour of paper, or even the colour of piano keys. They are a couple of shades darker than...

All female mammals have a clitoris, the sole purpose of which is to react to sexual stimulation, and presumably this stimulation has evolved to be pleasurable for most species. But establishing...

To create a sound, we have to set matter - whether it's a gas like air, a liquid or even a solid material - in regular motion, creating a wave of specific frequencies, which we hear as a sound of...

Mirrors don’t reverse left and right either – that’s just our interpretation of what happens. Your reflection in the mirror is actually reversed front to back – if you have...

Discovered by an American student named Gary Flandro in the mid-1960s, the slingshot manoeuvre usually involves spacecraft briefly 'coat-tailing' a planet orbiting the Sun, extracting some of the...

The ice disappears because the wind blows away water molecules that have evaporated or 'sublimed' from the ice, so the ice slowly shrinks in size. The molecules that escape are those with the...

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Empathy builds on the ability to see things from another person’s point of view, which most children acquire at around four or five years. But being fully empathic also means being able to...

Our skin contains lots of nerve endings that respond to different stimuli. There are receptors for touch, vibration, heat, cold and pain – but not for wetness. Water is such a ubiquitous...

It’s all down to the method of delivery. Venoms must be injected to be effective, whereas poisons can come into contact with skin, or be inhaled, eaten or touched. So the puffer fish is...

Reading is a complex, multi-layered process, starting with detecting letters, recognising words and groups of words, then analysing sentence structure and meaning.

Different areas of the...

Men grow beards because the hair follicles on their jaw are stimulated by the hormone dihydrotestosterone (DHT), which is produced from testosterone. Women have the same number of follicle cells...

Studies using functional magnetic resonance imaging (fMRI) have shown that scratching causes patterns of brain activity that are associated with pleasure and reward. This effect is strongest when...

Diet definitely affects the flavour of the milk of all mammals. A 2008 study at Copenhagen University gave flavour capsules to nursing mothers and found that the taste made its way into their...

Yes. When you wash your hands, you transfer a thin film of bacteria, skin flakes and oils to the bar of soap. A 2006 study of 32 dental clinics found bacteria growing on the soap in all of them...

Nickel-based batteries were blighted by the ‘memory effect’, and would lose capacity unless regularly discharged completely. Most phones nowadays have lithium batteries, and these do...

The ingredients required to make a rainbow are sunlight and raindrops. Currently, there is no other planet known to have liquid water on its surface or in sufficient quantities in the atmosphere...

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