General Science Questions (MCQs) for Competitive Examinations

Notes:
Swine influenza, also called pig influenza, swine flu, hog flu and pig flu, is an infection caused by any one of several types of swine influenza viruses. Swine flu, also known as the H1N1 virus, is a relatively new strain of an influenza virus that causes symptoms similar to the regular flu. It originated in pigs, but is now known to spread primarily from person to person.

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White blood cells (WBCs) are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. They are also called leukocytes. WBCs are found throughout the body, including the blood and lymphatic system.

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The reason why bacteria does not grow in high concentration of sugar is because of sugar’s high osmotic and dehydrating effects. Sugar, in aqueous form, attempts to reach equilibrium with the sugar content of the food product with which it is in contact. This has the effect of drawing available water from within the food to the outside and inserting sugar molecules into the food interior. The result is a reduction of the so-called product water activity, a measure of unbound, free water molecules in the food that is necessary for microbial survival and growth. Sugar’s other antimicrobial mechanisms include interference with a microbe’s enzyme activity.

Notes:
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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Hydrogen peroxide (H2O2) is a water molecule with an extra oxygen atom hence, also called oxygenated water. It is very unstable and breaks down readily into water and a single oxygen molecule. So in nutshell, when Hydrogen peroxide readily loses active oxygen, Water is formed.
2H2O2 —> 2H2O + O2

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In citrus fruits such as oranges, the nucleus cells that surround the embryo start dividing and protrude into the embryo sac. These develop into embryos; thus resulting in the presence of more than one embryo inside each ovule. This condition is known as polyembryony.

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Fertilization is the process of fusion of the male and the female gametes. This can occur either inside (internal fertilization) or outside (external fertilization) the body of the female. Humans provide an example of the former whereas seahorse reproduction is an example of the latter.

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Algae are chlorophyll (green pigment) containing thallophytes. They prepare their own food and are thus autotrophic in their mode of nutrition. Even liverworts among Bryophytes such as Riccia and Marchantia have thaloid structure.

Notes:
Bird and snake excretory product is uric acid. Nitrogenous waste is excreted in form of ammonia. In birds and reptiles, uric acid is the major end-product of protein metabolism. It is produced by the liver and excreted by kidney tubules; impaired elimination is an indication of renal disease.

Notes:
Water is transported through the plant in Xylem vessels, these begin in the roots and end in the leaves of the plant. Water is transported through a combination of “Transpirational pull” and capillary action that produces root pressure.