General Science Questions (MCQs) for Competitive Examinations

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Interbreeding destroys the genetic integrity of a species, causing it to become progressively infertile or extinct, evolutionary changes in anatomy and biology developed to prevent interbreeding between species. The specific term is Reproductive Isolation, which acts to prevent some, any, or all stages of reproduction from occurring. Reproductive Isolation is very important in keeping animal species separated.

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Sex determination in human beings depends on the particular pair of sex chromosomes an individual inherits. The homogametic sex, females, usually possess two identical sex chromosomes (XX). On the other hand, males, who are the heterogametic sex, typically present a pair of different sex chromosomes (XY). This distinct pair forms the blueprint that directs male physical and biological characteristics development.

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The yolk sac is a membranous sac attached to an embryo, providing early nourishment. It functions as the developmental circulatory system of the human embryo, before internal circulation begins. It carries out transfer of nutrients in weeks 2 and 3 when the uteroplacental circulation is established

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An insect is an organism having three pairs of jointed legs. Insects are small, land-dwelling arthropods. It has three distinct body sections : the head, thorax and abdomen. It has one pair of antennae (comprising the scapele, pedicel and flagellum), compound eyes and often one or two pairs of wings.

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Beriberi is a disease caused by a vitamin B1 (thiamine) deficiency. There are two types of the disease: wet beriberi and dry beriberi. Wet beriberi affects the heart and circulatory system. In extreme cases, wet beriberi can cause heart failure. Dry beriberi damages the nerves and can lead to a loss of muscle strength and eventually, muscle paralysis.

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Swine flu is a disease of pigs that can, in rare cases, be passed to humans. It is a highly contagious respiratory disease caused by one of many Influenza A viruses. The disease is spread among pigs by direct and indirect contact, aerosols, and from pigs that are infected but do not have symptoms.

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The Cell theory, first developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann, states that all organisms are composed of one or more cells, that cells are the fundamental unit of structure and function in all living organisms, and that all cells come from pre-existing cells. Cells are called the ‘Building Blocks of Life’ or the ‘Basic units of Life’.

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Glaucoma is a condition that causes damage to the eye’s optic nerve and gets worse over time. People with glaucoma can lose nerve tissue, resulting in vision loss. In the most common form of glaucoma, primary open angle glaucoma, the fluid pressure inside the eye increases and causes progressive damage to the optic nerve and loss of nerve fibres.

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Dolly was the world’s first cloned sheep. It was born on 5 July 1996. It was a female domestic sheep, and the first mammal cloned from an adult somatic cell, using the process of nuclear transfer. Dolly was cloned by Ian Wilmut, Keith Campbell and colleagues at the Roslin Institute, part of the University of Edinburgh, Scotland.

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Salt, fat and leavening agents such as yeast and baking soda are common ingredients, though bread may contain other ingredients also. Yeast plays an important role in bread-making. It ferments and grows when combined with “food” such as flour and/ or sugar, and warmed. Carbon dioxide is produced and trapped in the dough as tiny air bubbles which make the bread rise during cooking and give it its characteristic texture.