* Why do doctors heat the syringe before injecting?

-- S Khiani, Nasik

There are minute organisms in the air, on the objects around us and even on our body. These organisms are responsible for the fermentation of sugar cane juice or even the juice of grapes.

Some of these micro-organisms are helpful to man. But some can cause infections and fever. Heating the syringe destroys the micro-organisms.

* How long will it take us to reach the sun from the earth?

-- Vinod D Nair, Vasai (West)

The distance between the earth and the sun is approximately 93 million miles (or 150 million kilometres). Light travels at the speed of approximately 1,82,000 miles (3,00,000 kilometres) per second. Divide the distance by speed and you will know that it takes a little more than eight minutes. But of course, no life can survive on the sun. The temperature deep inside is more than 15 million degrees celsius. Even the surface temperature is 6,000 degrees celsius.

* Why is blood important for survival?

-- R K Joshi, Borivli (West)

Blood is the name given to specialised cells of various kinds, which are suspended in a liquid medium, called plasma. The main constituents of the blood are plasma, red blood cells, white blood cells and platelets. Blood does the job of transporting many important substances to and from the various organs of the human body.

Oxygen is absolutely vital for all actions and for proper functioning of the various organs of the human body, including the brain. The red blood cells in the blood contain haemoglobin, which carries oxygen. When the blood circulation is good, all the organs of the body receive the required oxygen through it. Oxygen is consumed during human activities and carbon-di-oxide is given out. The body gives out carbon di-oxide through lungs. Even carrying the carbon di-oxide to the lungs is done by the blood vessels. The food we eat is broken down into simpler constituents like glucose, amino acids, fatty acids during the process of digestion. The blood vessels in the intestines absorb these nutrients and carry them to various parts of the body.

* My father pours kerosene oil on the stagnant water near our house. He says it prevents the breeding of mosquitoes. How does this happen?

-- Vandana G Kenny, Goa

Mosquitoes lay eggs on the surface of stagnant water. Soon these eggs turn into larvae. These are called wrigglers. If kerosene oil is spread over the surface of the water, it clogs the breathing tubes of the wrigglers and kills them. This helps control malaria that is spread by a kind of mosquito, called Anopheles.

* Why are the eyes of all newborn babies closed?

-- Shobha, Bangalore

Inside the mother's womb, the baby lies curled up, with its eyes closed and its fists clenched. Birth exposes the baby to light. The baby takes time to open its eyes in bright light. Till it adjusts, its eyes remain closed for some time.

Copyright © 1997 Indian Express Newspapers (Bombay) Ltd.