Ask Mr Brain . . . all will be explained
Do aeroplanes have ignition keys?
Small planes that seat a few people have locks on the doors and ignition keys to start the engine.
Small planes are often parked in areas where security is not very high and they need keys and locks for the same reasons that cars sitting in car parks do.
However, commercial airliners do not have locks on the door or any ignition keys. Anyone could, in theory, jump into the pilot's seat in the cockpit, flick a few switches and fly away - if they knew how.
Airliners do not need locks because they are usually kept at airports when they are not flying. And busy flight schedules means they often do not spend a lot of time on the ground at airports.
Airports also have high security which has made the locking up of planes unnecessary as yet.
How are seedless grapes grown if they have no seeds?
They are grown from cuttings. Most commercially produced fruit today, such as blueberries, apples and cherries, are not grown from seeds but from cuttings.
For grapes, a piece of the vine is cut off and put into a solution that makes it sprout roots. Once roots develop, it is planted in soil and leaves and fruit eventually form. The new plant is genetically the same as the original.
Is chocolate poisonous for dogs?
There is a chemical in chocolate called theobromine that can cause problems for dogs if eaten in large quantities.
The chemical is toxic to a dog if it eats between 100 and 150 milligrams of it for each kilogram of the dog's body weight.
Different types of chocolate contain different amounts of theobromine. So more concentrated dark chocolate would be more dangerous than milk chocolate, for example.
Is it better to wear white or light- coloured clothes in hot weather?
Light-coloured clothing reflects the most heat, while black material absorbs infrared heat faster. So when you are in the sun, it is better to wear white or light-coloured clothing.
Black clothing absorbs so much more sunlight than white to the extent that its temperature can be five degrees Celsius higher.
The reason why people like the Bedouins of the Sinai desert wear black is that the heat absorbed by their clothes warms the air next to the skin. This air rises and leaves through the porous fabric, drawing in external air through the bottom of the clothing. This creates a draught and the wearer feels more comfortable as a continuous breeze blows past the body.
Graphic: SPBRAIGLO
