Can starfish grow arms? Starfish can grow arms. They can have as many as 40 arms which are called rays. In case a crab or other animal grabs its arm, the starfish abandons it and uses the others to escape. Later, it grows a new...
Which animals care for their young for the longest period? Most of the animals do not take care of their young for a long period of time. Gorillas and elephants however, are some of the animals which take care of their young for a long...
How is nuclear power used? Nuclear fusion is a process that is hard to control. We use only nuclear fission to produce nuclear power. Power stations have pressurized water reactors in which a radioactive substance like uranium is bombarded with neutrons. The atoms split, releasing...
What is carbon dating? Carbon-14 is an isotope which has a half-life of 5730 years. Every living thing on earth has this isotope but stops absorbing it when it dies. By examining ancient substances, we can make out how much the carbon in them has...
Why do people blink their eyes? The blinking of the eyes can be compared to the effect of windscreen wipers in cars. Eyelids are made of folds of skin which are raised and lowered by certain muscles. The eyelids work automatically. We blink our eyes...
What is semaphore? Semaphore is a signalling system which uses pairs of flags. Different flag positions represent different letters and numbers. In the days before ships communicated via radio, it was used between shins sailing in close proximity to each other.
What is the tundra? Tundra is the name given to the land of the arctic which is only covered by ice and snow in winter. During the summer season many species of plants grow there but because of the extreme cold their roots do not...
Where were the pyramids built? The Egyptians built the pyramids on the west bank of the Nile River. This place, where the sun set, was believed to be the land of the dead. Their homes came up on the east bank, which was believed to...
Why is the jelly fish transparent? It is rather rare for animals to have transparent or see-through bodies. But the jelly fish is an excellent example of one such creature. Their see-through bodies help them avoid detection as it is hard to see them when...
What is half-life? When we talk of the half-life of a radioactive substance we mean the rate at which the nuclei of its atoms are decaying. It is the time taken for half of the atoms in a sample of the substance to decay. It...
