General Science Questions (MCQs) for Competitive Examinations

Notes:
Bulbs are modified stems of some plants. The stem is modified to be a storage organ where the plant stores its reserve materials which it would use in times of need. It has a modified flower bud or other growth point that is surrounded by modified, fleshy leaves that are referred to as scales. Onion is the best example of bulb.

Notes:
Grasshoppers are a group of insects belonging to the suborder Caelifera. They have three main body parts, the head, the thorax and the abdomen. They breathe through a series of holes called ‘spiracles’ which are located along the sides of the body. On grasshoppers, there is a large round disc on the first segment next to the thorax. It is called a tympanum and is the grass-hopper’s ear.

Notes:
Chloroplast, found in plant cells, is the site of photosynthesis in plants to prepare food(glucose) for the plant with the use of energy. It is a green plastid that contains chlorophylls A and B that absorb visible light energy and convert it to usable chemical energy in photosynthesis.

Notes:
Water is transported through the plant in Xylem vessels, these begin in the roots and end in the leaves of the plant. Water is transported through a combination of “Transpirational pull” and capillary action that produces root pressure.

Notes:
Aflatoxin are naturally occurring mycotoxins that are produced by Aspergillus flavus and Aspergillus parasiticus, species of fungi. They have been associated with various diseases, such as aflatoxicosis, in livestock, domestic animals and humans throughout the world.

Notes:
The Widal test is used to help make a presumptive diagnosis of enteric fever, also known as typhoid fever. Typhid is the other test used to ascertain the diagnosis of typhoid fever.

Notes:
The nucleoplasm is the liquid or semi-liquid substance of the nucleus filling the space around the DNA and the nucleoli. It is a type of protoplasm that is made up mostly of water, a mixture of various molecules, and dissolved ions. It is completely enclosed within the nuclear membrane or nuclear envelope.

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:
Birds excrete their nitrogenous wastes as uric acid in the form of a paste. This involves a complex metabolic pathway that is energetically costly in comparison to processing of other nitrogenous wastes such as urea or ammonia, but has the advantages of reducing water loss and preventing dehydration. Uric acid is also excreted by terrestrial reptiles (snakes and lizards).

Notes:
DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA) . Mitochondria are structures within cells that convert the energy from food into a form that cells can use. The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T).