General Science Questions (MCQs) for Competitive Examinations

Notes:
Different fluids in the human body generally have a delicate range of acid-alkaline balance they maintain for optimal functioning. Human blood has a normal pH of about 7.41. The pH of urine has a wider range. Normal ranges for urine pH are from 4.5 to 8 and saliva has pH range of 6-8 to 7-0.

Notes:
Vitamins A, D, E, and K are the fat-soluble vitamins. Unlike water-soluble vitamins, these vitamins dissolve in fat and are stored in body tissues. Too much vitamin A, D, or K (Hypervitaminosis) can lead to increased levels that are unhealthy and can cause health consequences. For example, too much vitamin A can lead to birth defects.

Notes:
Mostly medicinal herbs grown from 30 to 90 cm in height. They reach up to 30 cm in diameter.

Notes:
The yolk sac is a membranous sac attached to an embryo, providing early nourishment. It functions as the developmental circulatory system of the human embryo, before internal circulation begins. It carries out transfer of nutrients in weeks 2 and 3 when the uteroplacental circulation is established

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During glycolysis, glucose is broken down in ten steps to two molecules of pyruvate in cytoplasm (in the cellular matrix called cytosol). It then enters the mitochondria where it is oxidised through the tricarboxylic acid cycle to carbon dioxide and water.

Notes:
The guard cells in dicot plants are kidney shaped and dumbbell shaped in monocots. When guard cells expand on the outer edges of the stoma, but not on the inner side, they result in kidney-shaped cells, leading to an opening or pore between the two guard cells for gas exchange.

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:
The term xerophyte refers to a plant species that has evolved over time to adapt to dry and arid regions like deserts. Xerophytes have adapted to be able to keep extremely large amounts of water for a long period of time. Without this capability, the plant would die, as the desert region itself does not provide enough water to sustain life. They have thick cuticle, sunken stomata and leaves modified in form of spines such as in opuntia.

Notes:
The activity of enzymes, which are generally globular proteins, is determined by their three-dimensional structure. This structure allows them to bind to a substrate and catalyze their involvement in a reaction. Enzymes vary in size, ranging from 62 amino acid residues for the monomer of 4-oxalocrotonate tautomerase, to over 2,500 residues in animal fatty acid synthase. Their specific ability to bind to substrates enables reactions to occur in the body, playing a crucial role in metabolism.

Notes:
Cell theory was first developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann. They stated that all organisms are composed of one or more cells, that cells are the fundamental unit of structure and function in all living organisms, and that all cells come from pre-existing cells.