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:
Chemical weapons are called “poorman’s bomb”. These cause catastrophic damage, and are easy to produce. Sarin is a colorless and odourless agent, and is extremely potent. It was used in Damascus in 2013. Mustard Gas is possibly the most commonly used chemical agent and gets its name from the distinctive odour of rotten mustard. It is less potent and usually only 5 to 10 percent people exposed to it usually die. It was widely used during Second World War. VX is a nerve agent which is odourless and appears as brownish oily substance.

Notes:
Nickel, Platinum and Darmstadtium belongs to Group number 10 whereas element Roentgenium is placed in group number 11.

Notes:
Edible seaweed products have been consumed in many Asian countries. Edible seaweeds accumulate iodine from seawater and are therefore a good dietary source of iodine. Adequate consumption of seaweed can eliminate iodine deficiency disorders, but excessive iodine intake is not good for health. The recommended dietary reference intake of 0.15 mg/d and 0.14 mg/d for iodine has been established in the United States and Taiwan, respectively. Seaweed is an excellent source of iodine. However, the amount it contains depends on the species. Kombu kelp offers the highest amount of iodine, with some varieties containing nearly 2,000% of the daily value in one gram. Seaweed is a source of iodine, necessary for thyroid function and to prevent goitre. However, an excess of iodine is suspected in the heightened cancer risk in Japanese who consume a lot of the plant, and even bigger risks in post-menopausal women.

Notes:
During hibernation in winter, toads or frogs spend the time tucked away deep in the soil, in the mud underwater or hidden amidst foliage or rotting plants. Outside of times of hibernation, they usually take in oxygen via the air, employing their lungs. However, during hibernation, they receive their necessary oxygen through their permeable skin. This is referred to as cutaneous gas exchange.

Notes:
Infection is the invasion of an organism’s body tissues by disease-causing agents, their multiplication, and the reaction of host tissues to the infectious agents and the toxins they produce. Infectious diseases can be spread from one person to another, for example through contact with bodily fluids, by aerosols (through coughing and sneezing), or via a vector, for example a mosquito.

Notes:
While fertilization is necessary for organisms that reproduce sexually, individuals that reproduce asexually?do so without the need for fertilization. These organisms produce genetically identical copies of themselves through?binary fission, budding, fragmentation, parthenogenesis, or other forms of asexual reproduction.

Notes:
Chameleons have specialized cells, chromatophores, which contain pigments in their cytoplasm, in three layers below their transparent outer skin. Dispersion of the pigment granules in the chromatophores sets the intensity of each color. Chromatophores contain pigments and reflect light, which are responsible for creating coloration. In chameleons, there are four types of chromatophores: xanthophores, erythrophores, iridiophores, and melanophores (Cooper and Greenberg, 1992).

Notes:
A typical adult human stomach will secrete about 1.5 liters of gastric acid daily. The best-known component of gastric juice is hydrochloric acid, the secretory product of the parietal, or oxyntic cell. It is known that the capacity of the stomach to secrete HCl is almost linearly related to parietal cell numbers.

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.