General Science Questions (MCQs) for Competitive Examinations

Notes:
As per the Mohs scale of mineral hardness, the soft metals are: Lead, gold, silver, tin, zinc, aluminium, thorium, copper, brass and bronze. Diamond is one of the hardest known metals on earth.

Notes:
Land snails, insects, birds, and some reptiles excrete uric acid as the major nitrogenous waste. The white, crystalline substance seen in a typical bird or lizard “poop” is actually urine: a little pool of uric acid crystals in a very small amount of water.

Notes:
Female gametes are also called eggs or ova. They are created during the cellular reproduction process known as meiosis. The resulting gamete cell is a haploid cell. When the two haploid cells, the egg and sperm, fuse together during fertilization, the result is a diploid cell called a zygote.

Notes:
Bacteriophage refers to any of a group of viruses that infect bacteria. Bacteriophages were discovered independently by Frederick W. Twort in Great Britain (1915) and Felix d’Herelle in France (1917). D’Herelle coined the term Bacteriophage, meaning “bacteria eater”.

Notes:
Swedish naturalist Carlous Linnaeus established the binomial system of naming living organisms, setting a format and a structured process for classifying the interrelationships between plants (among which he included all fungi), and between animals. The binomial system that Linnaeus devised enables an author to refer to a species confident that it will mean the same thing to informed readers anywhere else in the world.

Notes:
The best-known and most common chromosome abnormality in humans is Down’s syndrome, (Trisomy of 21st pair of chromosome). Down’s syndrome individuals also almost invariably develop Alzheimer’s disease, a form of dementia that is fairly common among the elderly people. People with Down’s syndrome develop this disease in their fourth or fifth decade of life, much sooner than other people. These people are also characterized by presence of webbed neck, Plamers crease, very broad forehead, round face and forked tongue.

Notes:
Photosynthesis is the process by which plants, some bacteria and some protistans use the energy from sunlight to produce glucose from carbon dioxide and water. This glucose can be converted into pyruvate which releases adenosine triphosphate (ATP) by cellular respiration. Oxy-gen is released through the stomata on the underside of the leaf; glucose is transported around the plant in the phloem vessels.

Notes:
Cecum is a pouch connected to the junction of the small and large intestines. It is a large tube-like structure in the lower abdominal cavity that receives undigested food material from the small intestine and is considered the first region of the large intestine. It is separated from the ileum (the final portion of the small intestine) by the ileocecal valve (also called Bauhin valve). The main functions of the cecum are to absorb fluids and salts that remain after completion of intestinal digestion and absorption and to mix its contents with a lubricating substance, mucus.

Notes:
Plants which either obtain readymade organic food prepared by other plants or absorb water and minerals from other plants to prepare their own organic food are called parasitic plants. Cuscuta (Doddar) is a total stem parasite.

Notes:
The chromosomes which determine the sex (maleness or femaleness) of an individual in sexually producing organisms are called sex chromosomes or allosomes. In humans an individual whose cells contain XX chromosomes (homo or isogametic) becomes a female, while one whose cells contains XY chromosomes (heterogametic) becomes a male.