General Science Questions (MCQs) for Competitive Examinations

Notes:
Turner syndrome is a rare chromosomal disorder characterized by partial or complete loss (monosomy) of one of the X chromosomes that affects females. Individuals with Turner syndrome have only 45 chromosomes, including just a single X chromosome. This monosomic has a chromosome complement of 44 autosomes and one X chromosome (44+XO). The abnormal condition probably originates from exceptional egg or sperm with no X chromosome.

Notes:
The ear has three main parts: the outer, middle and inner ear. The outer ear consists of the pinna and the auditory canal. The middle ear is filled with air and contains three tiny bones called ossicles – the anvil, hammer and stirrup. The inner ear contains the semicircular canals and the cochlea. Eardrum is the membrane of middle ear. Snakes have fully developed inner ear structures but no eardrum.

Notes:
Calyptrogen is a layer of rapidly dividing cells at the tip of a plant root, from which the root cap is formed. It occurs in grasses and many other plants. The root cap is formed by several layers of cells that envelop the root tip externally. This covering of cells, of which the outermost ones are dead, envelops and protects the growing tip of root.

Notes:
The small intestine, the part of the gastrointestinal tract between the stomach and the large intestine, is the main digester and absorber of food. The small intestine has three distinct regions – the duodenum, jejunum, and ileum–that carry out the absorption of nutrients and minerals from food. It converts the food into a semi-solid mass.

Notes:
Abscisic acid also called plant stress hormone is responsible for responsible for dormancy of various types. It maintains dormancy in seeds and buds, stimulates the closing of stomata. Gibberellins are responsible for cell division and growth in cell size.

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Typhoid fever, also known simply as typhoid, is a bacterial infection due to Salmonella typhi, also known as Salmonella enterica serotype typhi, that grows in the intestines and blood. Typhoid is spread by eating or drinking food or water contaminated with the feces of an infected person.

Notes:
The word “protoplasm” comes from the Greek protos for first, and plasma for thing formed, and was originally used in religious contexts. It was first used for living cells by J. E. Purkinje, a Czech anatomist and physiologist, in 1839. He used protoplasm for the fluid substance of a cell.

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A biomass is total quantity of weight of the planet that can be classified according to the plants and animals that live in it. Temperature, soil, and the amount of light and water help determine what life exists in a biome.

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Strontium-90 is a radioactive isotope of strontium produced by nuclear fission. Used mostly in weapons and nuclear power plants, poisoning usually occurs through accidental ingestion. Studies have also linked strontium-90 to various forms of skin cancer.

Notes:
Vaccines containing antigens are introduced into the body, stimulating the immune system response by instructing B cells, with assistance from T cells, to produce antibodies. Antibodies are produced to fight the weakened or dead viruses in the vaccine. The immune system prepares to destroy real and stronger viruses in the future. When new antigens enter the body, white blood cells called macrophages engulf them; process the information contained in the antigens, and send it to the T cells to mobilise immune system. Hence, introduction of antigens in any form in body induces the production of antibodies to boost immunity.