General Science Questions (MCQs) for Competitive Examinations

Notes:
Thrombin is a serine protease, an enzyme, that is at the centre of blood clotting process in human beings. It catalyzes the conversion of fibrinogen to fibrin and activates procoagulant factors V, VIII, XI, and XIII. Additionally, when bound to thrombo-modulin, it activates protein C, an anticoagulant zymogen.

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:
In general, liver is a good source of vitamin A, iron, zinc, copper and manganese, and a very good source of protein. There are twenty grams of protein in a single slice of liver.

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Vitamin K refers to a group of fat-soluble vitamins that play a role in blood clotting, bone metabolism, and regulating blood calcium levels. The body needs vitamin K to produce prothrombin, a protein and clotting factor that is important in blood clotting and bone metabolism.

Notes:
There are three types of heterotrophs: herbivores, carnivores and omnivores. Also referred to as consumers, heterotrophs are organisms that obtain their energy from organic compounds. In other words, they are organisms that are unable to produce their own food (unlike autotrophs) and therefore have to consume/ ingest organic compounds as a source of energy.

Notes:
The arteries (red) carry oxygen and nutrients away from your heart, to your body’s tissues. The veins (blue) take oxygen-poor blood back to theheart. Arteries begin with the aorta, the large artery leaving the heart. They carry oxygen-rich blood away from the heart to all of the body’s tissues.

Notes:
Ornithophily refers to the pollination of flowering plants by birds. Birds involved in ornithophily tend to be specialist nectarivores with brushy tongues and long bills, that are either capable of hovering flight or light enough to perch on the flower structures.

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:
Scurvy also once called ‘Sailor’s disease’ is a condition where an individual has a vitamin C (ascorbic acid) deficiency. Scurvy often presents itself initially as symptoms of malaise and lethargy, followed by formation of spots on the skin, spongy gums, and bleeding from the mucous membranes. Spots are most abundant on the thighs and legs, and a person with the ailment looks pale, feels depressed, and is partially immobilized. As scurvy advances, there can be open, suppurating wounds, loss of teeth, jaundice, fever, neuropathy and death.

Notes:
Poliomyelitis, often called polio or infantile paralysis, is an infectious disease caused by the poliovirus. The virus is transmitted by person-to-person spread mainly through the faecal-oral route or, less frequently, by a common vehicle (e.g. contaminated water or food) and multiplies in the intestine, from where it can invade the nervous system and can cause paralysis.