General Science Questions (MCQs) for Competitive Examinations

Notes:
Sublimation describes a phase transition where a substance changes from a solid directly to a gas, bypassing the liquid state. This physical transformation is distinct from chemical changes like oxidation or reduction. Sublimation happens under certain combinations of pressure and temperature. Examples include dry ice (solid CO2), which sublimates at room temperature, and solid water, or ice, which sublimates under low pressure conditions.

Notes:
The brain’s limbic system controls emotional expression through the hypothalamus, which has control over the body’s emotional responses systems. The hypothalamus is responsible for regulating hunger, thirst, response to pain, levels of pleasure, sexual satisfaction, anger and aggressive behavior, etc. It also regulates pulse, blood pressure, breathing, and arousal in response to emotional circumstances.

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:
Newton’s Law of Cooling states that the rate of temperature of the body is proportional to the difference between the temperature of the body and that of the surrounding medium. When a body cools by radiation, then rate of cooling depends on: Nature of the radiating surface, that is, emissivity; Area of the radiating surface; Mass of the radiating surface; Specific heat of the radiating body; Temperature of radiating body and Temperature of the surrounding.

Notes:
Vitamin C is quite unstable when cooked or stored improperly. It is very liable and easily destroyed during cooking as well as storage. It is a water-soluble and temperature-sensitive vitamin, so is easily degraded during cooking, and elevated temperatures and long cooking times have been found to cause particularly severe losses of vitamin C.

Notes:
An osteocyte, a star shaped cell, is the most commonly found cell in mature bone, and can live as long as the organism itself. Osteocytes are networked to each other via long cytoplasmic extensions that occupy tiny canals called canaliculi, which are used for exchange of nutrients and waste through gap junctions. The space that an osteocyte occupies is called a lacuna.

Notes:
The swim bladder is an internal gas-filled organ that contributes to the ability of a fish to control its buoyancy, and thus to stay at the current water depth without having to waste energy in swimming. The cartilaginous fish (e.g. sharks and rays) split from the other fishes about 420 million years ago and lack both lungs and swim bladders, suggesting that these structures evolved after that split.

Notes:
Bacteria are the most abundant organisms which play important role in the decomposition of organic matter. Majority of bacteria involved in decomposition of organic matter are heterotrophs and autotrophs are least in proportion which are not directly involved in organic matter decomposition.

Notes:
Persons with AIDS, Hepatitis B and C, Rabies, Septicaemia, Acute leukemia (Blood cancer), Tetanus, Cholera, and infectious diseases like Meningitis and Encephalitis cannot donate eyes. Even people with diabetes, asthma, hypertension, or persons wearing spectacles and who had undergone cataract surgery can also donate eyes.

Notes:
The open circulatory system is a system in which fluid in a cavity called the hemocoel bathes the organs directly with oxygen and nutrients and there is no distinction between blood and interstitial fluid; this combined fluid is called hemolymph. Arthropods and mollusks have an open circulatory system.