General Science Questions (MCQs) for Competitive Examinations

Notes:
Tusks are elongated, continuously growing front teeth, usually but not always in pairs, that protrude well beyond the mouth of certain mammal species. They are most commonly canines, as with warthogs, pig, and walruses, or, in the case of elephants, elongated incisors. The tusks are actually upper incisors, not canines. They are the only incisors the elephant has. Elephants, mastodons, and mammoths all have upper incisor teeth that emerge from the skull as tusks.

Notes:
The pattern of arrangement of leaves on the stem is called Phyllotaxy. As a stem grows at its apex, new leaf buds form along the stem by a highly controlled developmental process. Leaf arrangement along the plant stem depends on the species and is an important identifying characteristic. There are four basic types of phyllotaxy: alternate, spiral, opposite and whorled.

Notes:
Vitamin K is a group of structurally similar, fat-soluble vitamins that are needed for the post translational modification of certain proteins required for blood coagulation i.e. conversion of fibrinogen into fibrin, the blood clot. and in metabolic pathways in bone and other tissue. They are 2-methyl-1,4- naphthoquinone (3-)derivatives. This group of vitamins includes two natural vitamins: vitamin K1 and vitamin K2. Vitamin K1, also known as phylloquinone, phytomenadione, or phytonadione, is synthesized by plants, and is found in highest amounts in green leafy vegetables because it is directly involved in photosynthesis. It may be thought of as the “plant form” of vitamin K. It is active in animals since animals can easily convert it to vitamin K2.

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Haptens are small molecules that react with a specific antibody but cannot induce the formation of antibodies unless bound to a carrier protein or other large antigenic molecule. They are incomplete or partial antigens.

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Keratin is a family of fibrous structural proteins that is the key structural material making up hair, horns, claws, hooves, and the outer layer of human skin. Keratin is also the protein that protects epithelial cells from damage or stress. Some keratins have also been found to regulate key cellular activities, such as cell growth and protein synthesis.

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Transport of soluble products of photosynthesis is called translocation. Translocation of soluble products of photosynthesis occurs in the part of the vascular tissue known as the phloem. The phloem is the principle food conducting tissue associated with xylem in the vascular system.

Notes:
Keratin is one of a family of fibrous structural proteins that is the key structural material making up hair, nails, horns, claws, hooves, and the outer layer of human skin. Keratin is also the protein that protects epithelial cells from damage or stress.

Notes:
The carrot gets its characteristic and bright orange colour from ?-carotene, which is partly metabolised into vitamin A in liver of humans. Carotene is responsible for the orange colour of carrots and many other fruits and vegetables. Carotene is an orange photosynthetic pigment important for photosynthesis.

Notes:
Damping off is a horticultural disease or condition, caused by a number of different pathogens that kill or weaken seeds or seedlings before or after they germinate. Pythium, a genus of parasitic oomycete, are most often responsible for damping-off. Along with Rhizoctonia solani, attacks by Pythium are most associated with producing roughly circular patches of dead seedlings.

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Measles is an infectious disease caused by the rubeola virus. It is transmitted via droplets from the nose, mouth or throat of infected persons. It remains an important cause of death among young children globally, despite the availability of a safe and effective vaccine.