Nature gauntlet
Every question we've got in Nature, back to back. How far can you get?
- Question 1 of 12
Besides contentment, when else do cats purr?
Cats purr when stressed, injured, frightened, giving birth and even near death, which is why researchers think the purr functions partly as a self-soothing signal rather than a mood report.
Read the full answer → - Question 2 of 12
Why is it disputed whether obelisks are 'alive'?
Like viruses and viroids, obelisks cannot move, feed, or self-replicate on their own and must use a host cell, placing them on the disputed border between chemistry and life.
Read the full answer → - Question 3 of 12
How honestly can science explain the bird's magnetic receptor?
The actual receptor has never been conclusively found in a living bird; the field is often called a sense without a receptor, and the sensory molecule remains unconfirmed.
Read the full answer → - Question 4 of 12
That lovely fresh-cut-grass smell is actually the plant doing what?
The smell is a wound response. Cutting or crushing the blade ruptures its cells and triggers the lipoxygenase pathway, which throws off a burst of green leaf volatiles (dominated by cis-3-hexenal) within seconds. The signal primes nearby plants to arm their defences and summons predators of the bugs eating it. You're relaxing on the lawn while the grass is, in effect, screaming.
Read the full answer → - Question 5 of 12
In the original study, where were obelisks most often detected?
Obelisks turned up in roughly 7% of analysed stool samples and about 50% of oral samples; a later global survey catalogued nearly 30,000 distinct obelisks across many niches.
Read the full answer → - Question 6 of 12
How should the 2001 Hamilton and Brown aphid-signal hypothesis be described?
Hamilton and Brown proposed that bright autumn colour signals a tree's vigour and defences to aphids. It's elegant and has some correlational support, but other studies found aphids don't choose hosts by colour, and the sunscreen idea covers the same facts. Treat it as a contested maybe.
Read the full answer → - Question 7 of 12
Where is a wombat's cube-shaped dropping actually formed?
The corners are moulded in the last stretch of the intestine, well before the round exit. The wombat's rear opening is perfectly ordinary and round: the cube is already fully shaped by the time it gets there.
Read the full answer → - Question 8 of 12
So what actually keeps a woodpecker's brain safe?
What injures a brain is the pressure that builds inside the skull, and a smaller brain generates less pressure from the same jolt. A woodpecker brain is about one-seventh the length of ours, so the pressure during a peck stays two to three times below the human concussion threshold.
Read the full answer → - Question 9 of 12
Why are wombat droppings dry enough to hold a cube shape?
Wombats live on poor, dry grass and run one of the slowest guts of any mammal, so nearly all the water is reabsorbed. The near-solid material that is left can take an edge and keep it, instead of slumping into a blob.
Read the full answer → - Question 10 of 12
How much muscular effort does a flamingo use to hold its one-legged stance?
The leg locks into a passive gravitational stay, so the skeleton and gravity hold the body up and the muscles barely fire. That is why a flamingo can rest, and even sleep, in the pose for long stretches without tiring.
Read the full answer → - Question 11 of 12
When is a dog's head tilt a medical warning sign?
A tilt prompted by a sound that then relaxes is normal. A persistent tilt held constantly, even in silence, is a red flag for vestibular disease or an inner-ear infection, especially with stumbling, circling or flicking eyes, and warrants a vet.
Read the full answer → - Question 12 of 12
Is human blood ever actually blue?
Blood is never blue inside you. Deoxygenated venous blood is dark red, not blue, and it does not change colour on contact with air. The idea that it turns red only when it meets oxygen is a myth, reinforced by diagrams that colour veins blue.
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