General Science Questions (MCQs) for Competitive Examinations

Notes:
Vitamin D is a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, and multiple other biological effects. It is usually produced in the skin of human and animals under the influence of solar or ultraviolet radiation. In plants it can be produced from provitamin ergosterol.

Notes:
In molybdenum-deficient plants grown in the presence of nitrate, molybdenum is required for the synthesis of nitrate reductase. Molybdenum deficiency results in the decrease of free amino acids in the plants in comparison to normal plants.

Notes:
In biology, a pathogen or germ is anything that can produce disease. Typically, the term is used to describe an infectious agent such as a virus, bacterium, protozoa, prion, a fungus, or other microorganism. The scientific study of pathogens is called Pathology.

Notes:
Curcumin is the principal curcuminoid of the popular Indian spice turmeric, a member of the ginger family. The curcuminoids are natural phenols that are responsible for the yellow color of turmeric.

Notes:
The gizzard is an organ that grinds food in the gastric mill similar to the way humans use teeth. It is present in certain animals like archosaurs (includes dinosaurs, birds and crocodiles), some types of fish, and some crustaceans. In birds, it is often aided by bits of grit or stone that the animal has swallowed. It is not present in mammals, including primates and giraffes.

Notes:
Argon is produced industrially by the fractional distillation of liquid air. Argon is mostly used as an inert shielding gas in welding and other high-temperature industrial processes where ordinarily non-reactive substances become reactive; for example, an argon atmosphere is used in graphite electric furnaces to prevent the graphite from burning.

Notes:
Carbon particles in air are colloidal in nature and carry negative charge. The removal of carbon particles from air involves the principle of electrophoresis. Carbon particles get precipitated by losing their charge and, thus, the air which finally comes out is free from them.

Notes:
Chloroform can be used as Anaesthetic. Chloroform (CHCl3) on heating with silver powder undergoes dehalogenation to form Ethyne. It is also an important source for producing foxic phosgene gas.

Notes:
Vinegar is a liquid consisting of about 5–20% acetic acid (CH3COOH), water, and other trace chemicals. Acetic acid is the major characterizing component of vinegar. Its concentration determines the stren-gth of the vinegar, a value termed ‘grain strength,’ which is equal to 10 times the acetic acid concentration.

Notes:
Esters are sweet-smelling substances.

• It is used to make perfumes.
• Ammonia had unpleasant smell.
• Methanol has pungent odor.
• Ethanol had a sweet smell.