Why do tidal waves occur? Tidal waves or tsunamis are caused by sudden movements of the earth under the se Such waves occur during an earthquake. Initially water is sucked away from the coast as if by a giant vaccum cleaner, followed by the tsunami...
What is the nitrogen cycle? Nitrogen is very important for the survival of plants, animals and humans. Plants take simple nitrogen compounds from the soil. Animals get nitrogen by eating plants. Nitrogen returns to the soil as waste. Bacteria convert the waste into simple nitrogen...
Why do plants make starch? Human beings get starch from plants where it is found as small grains. Plants make starch which serves as food for seedlings and new shoots until they are able to make their own food materials. Sunlight and chlorophyll, as well...
Can a porcupine shoot its quills? Porcupine quills are loosely fastened to the body of the porcupine. When an enemy attacks a porcupine, the latter swings its tail into the attacker’s face. This makes the quills fly out making it seem as if the quills...
What is cataract of the eye? In the old days, people believed that cataract of the eye was caused by an opaque film that came down like a cataract or waterfall over the lens of the eye. Cataracts are cloudy or opaque discolourations within the...
Why don’t women have beards? Hair has different uses in different mammals. Development of hair in adult human beings is regulated by sex glands. In males, the sex hormone causes hair growth on the face like the beard and moustache. But in women, sex hormones...
What makes the planet Saturn special? Saturn has two special features. One is that it is surrounded by a set of bright, shining rings. This makes it a beautiful sight to behold. Another factor is that Saturn is the lightest of all the planets. It...
Why is Neptune blue? The presence of methane gas in the atmosphere gives Neptune its blue colour. Methane absorbs the red colour in sunlight. Because of this, the light coming from Neptune’s atmosphere appears blue. Like Neptune, earth also has a blue colour.
How does the seismograph measure an earthquake? Seismographs record the vibrations of the earth. It is a delicately hung weight which remains still when an earthquake occurs. But the post which holds it, moves. There is a chart which is attached to the post under...
Which dinosaur had the largest feet? Many dinosaurs had large feet. Sauropods like Brachiosaurus had huge front feet which measured one metre in length. Some of the fossilized footprints of sauropods were so big that one can sit in them. A dinosaur’s feet had to...
