General Science Questions (MCQs) for Competitive Examinations

Notes:
The inner walls of the small intestine have thousands of finger-like outgrowths called villi (singular villus). The villi increases the absorption of the digested food. Each villus has a network of thin and small blood vessels close to its surface. The surface of the villi absorbs the digested food materials.

Notes:
Oils are unsaturated carbon compounds that have double or triple bonds. Double and triple bonds are easy to be digested or to be broken down into simpler substances. But if a saturated compounds like Vanaspati Ghee are used, it becomes difficult for our body to digest the food as single bonds are not easily broken down into simpler substances by the acids present in our body. Animal fat is a saturated fat in which the fatty acid chains have all or predominantly single bonds. It is made of long chains of carbon (C) atoms. Saturated fatty acids are straight-chain organic acids with an even number of carbon atoms. They raise the serum LDL cholesterol concentration when they are consumed in the diet. So, they are harmful for our health.

Notes:
A vector-borne disease is one in which the pathogenic microorganism is transmitted from an infected individual to healthy individual by an arthropod or other agent, sometimes with other animals serving as intermediary hosts. The transmission depends upon the attributes and requirements of at least three different living organisms: the pathogenic agent, either a virus, protozoa, bacteria, or helminth (worm); the vector, which are commonly arthropods such as ticks or mosquitoes; and the human host.

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Bacillus Calmette Guerin is a vaccine against tuberculosis. BCG vaccine can be implemented after the birth intradermally within 2-3 days.

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Water stomata, also known as hydathodes, are structurally modified portions of leaf which are meant to send out excess amount of water in liquid form. They are present usually at the rip or margins of leaves of those plants that grow in moist places. They secrete water through pores in the epidermis or leaf margin, typically at the tip of a marginal tooth or serration. Hydathodes are commonly seen in water lettuce, water hyacinth, rose, balsam, etc.

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The smallest objects that can be seen with unaided eye are about 0.1 mm long, which is equal to 100 micrometres. Micron (u) is an alternate name of micrometre.

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The abundant enzyme in the living world is Rubisco. It is a key regulator of non-steady state of photosynthesis. Ribulose-1,5-bisphosphate carboxylase oxygenase, most commonly known by the shorter name RuBisCO, is an enzyme that catalyses the first major step of carbon fixation, a process by which atmospheric carbon dioxide and water are converted to energy-rich molecules such as glucose, using sunlight.

Notes:
The molar mass is the mass of a given chemical element or chemical compound (g) divided by the amount of substance (mol). The molar mass of the given noble gases are as follows:

• Argon (Ar): 39.9480 g/mol;
• Neon (Ne): 50.1858 g/mol;
• Krypton (Kr): 83.7980 g/mol;
• Xenon (Xe): 131.2930 g/mol.

Notes:
Cement (e.g., Portland cement) hardens because of hydration a chemical reaction that occurs independently with the mixture’s water content; they can harden even underwater or when constantly exposed to wet weather. The chemical reaction that results when the anhydrous cement powder is mixed with water produces hydrates that are not water-soluble.

Notes:
Ethylene glycol (IUPAC name: ethane-1,2-diol) is an organic compound widely used as an automotive antifreeze and a precursor to polymers. In its pure form, it is an odorless, colourless, syrupy, sweet-tasting liquid. Due to its low freezing point ethylene glycol resists freezing. A mixture of 60% ethylene glycol and 40% water freezes at -45 degree C (-49 degree F).