Man has only one X-chromosome that is inherited to his daughter. Therefore, a hereditary disease, which is X-chromosomal linked, is never passed on from father to son.

Amount of Co, in expired air is 4.4%. The air we breathe in contains about 0.04% CO,. The air we breathe out contains about 4% CO,. In other words, exhaled air contains about 100 times the concentration of CO, that inhaled air does.

The Devonian Perioid is known as 'the age of fishes'. It is famous for the thousands of species of fish that developed in Devonian sea. The Devonian Period of Palacozonic Era lasted from 417 million years ago to 354 million years ago.

In genetic engineering DNA technology is applied to several biotechnological processes for obtaining particular biochemical improvement of the genetic makeup of an organism and fighting genetic defects.

In RNA the thymine of DNA is replaced by uracil. Codon and anticodon both found on RNA and are complementary to each other so, the codon for anticodon 3-UUUA-5' will be 5-AAUU-3.

Baccillus Calmette Guerin (BCG) is the vaccine for tuberculosis. It was first used in 1921. BCG is the only vaccine available today for protection against tuberculosis. It is most effective in protecting children from the disease. BCG contains a live attenuated (weakened) strain of Mycobacterium bovis. This vaccine was developed by Calmette and Guerin at Pasteur Institute, Paris.

Sir Godfrey Newbold Hounsfield, an English electrical engineer who shared th 1979 Nobel Prize for Physiology or Medicine with Allan MacLeod Cormak for his part in developing diagnostic technique of X-ray computed tomogrpahy (CT) scanning. He died in August 2004.

In water, mercury gets changed into water-soluble dimethyl form and enters the food chain accompanied by biological amplification. It develops a crippling deformity called Minamata disease.

The first biotic community which develops in a bare area is called the pioneer community. The climax community is the stable, self-perpetuating and final biotic community that develops at the end of biotic succession. The various biotic communities that develop during biotic succession are termed as seral or transitional communities.

Alcoholism is a chronic, often progressive disease in which a person craves alcohol and drinks despite repeated alcohol related problems. It involves a physical dependence on alcohol. It may lead to liver cirrhosis. Cirrhosis is build up of scar tissue that changes the structure of the liver and blocks blood flow. Cirrhosis can cause varicose veins, which can rupture and potentially triggering internal bleeding.