General Science Questions (MCQs) for Competitive Examinations

Notes:
The carat is the common unit used to describe the mass of a gem. A 1-carat diamond, for example, has a mass of 0.20 g. The karat is the common unit used to describe the purity of a precious metal, such as gold. A 24-karat gold ring is as pure as can be. A gold ring that is 50 % pure is 12 karat.

Notes:
Radium is a chemical element with the symbol Ra and atomic number 88. Radium was discovered by Marie Sklodowska Curie, a Polish chemist, and Pierre Curie, a French chemist, in 1898.

Notes:
Radon, a radioactive noble gas with atomic number 86, is used in radiotherapy. Created by disintegration of radium, its one of the heaviest gases and a health hazard. Radon gas, chemically inert yet radioactive, can accumulate in buildings and drinking water causing lung cancer. Furthermore, radon is noted for brilliant phosphorescence when cooled below its freezing point. Its most stable isotope, 222Rn, has a half-life of 3.8 days. Groundwater often has a higher 222Rn concentration than surface water due to less exposure to atmosphere.

Notes:
Lysosomes are called the suicide bags of the cells they contain digestive enzymes, and break down food, cellular debris and foreign invaders like bacteria. When the cell is injured beyond repair, or becomes old, the lysosome digests the cell. So, it is called “suicide bag of the cell.”

Notes:
Mitochondria is an organelle found in large numbers in most cells, in which the biochemical processes of respiration and energy production occur. It is for this reason that mitochondria are often referred to as the powerhouses of the cell mitochondria also play a key role in the ageing process as well as in the onset of degenerative disease.

Notes:
Land snails, insects, birds, and some reptiles excrete uric acid as the major nitrogenous waste. The white, crystalline substance seen in a typical bird or lizard “poop” is actually urine: a little pool of uric acid crystals in a very small amount of water.

Notes:
Solitary cymose inflorescence refers to a determinate inflorescence composed of a single flower. Examples include poppy, gardenia (ornamental plant), tulip, etc. Flowers are said to be solitary when the plant bears only one, or when single flowers appear on the ends of lateral branches that are remote from one another.

Notes:
Mould is a member of the fungi kingdom. Fungi can be defined as a plant without chlorophyll, so it cannot get energy directly from the sun. This means that fungi must use other plants and animals as its food source. This is why bread mould is so common because of the ingredients in bread, it is an excellent source of nutrition for many moulds to grow and thrive.

Notes:
Sharks possess a heterocercal caudal fin in which the dorsal portion is usually noticeably larger than the ventral portion. This is because the shark’s vertebral column extends into the dorsal portion, providing a greater surface area for muscle attachment.

Notes:
Smallpox was an infectious disease caused by either of two virus variants, Variola major and Variola minor. After vaccination campaigns throughout the 19th and 20th centuries, the WHO certified the global eradication of smallpox in 1979. Smallpox is one of two infectious diseases to have been eradicated, the other being Rinderpest.