General Science Questions (MCQs) for Competitive Examinations

Notes:
Thyroxine is the main hormone secreted into the bloodstream by the thyroid gland. It plays vital roles in digestion, heart and muscle function, brain development and maintenance of bones. It increases heart rate, cardiac contractility and cardiac output and also promotes vasodilation, which leads to enhanced blood flow to many organs.

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.

Notes:
Pasteurisation is a process of heating milk for 30 minutes at 62° C and cooling rapidly to kill harmful bacteria and prevent their further proliferaction. Because of the nature of the heat treatment it sometimes referred to as the ‘High Temperature Short Time’ (HTST) process. Once the milk has been heated, it is then cooled very quickly to less than 3°C.

Notes:
A pulmonary artery is an artery in the pulmonary circulation that carries deoxygenated blood from the right side of the heart to the lungs. The pulmonary arteries are unique in that unlike most arteries which carry oxygenated blood to other parts of the body, the pulmonary arteries carry de-oxygenated blood to the lungs. After picking up oxygen, the oxygen rich blood is returned to the heart via the pulmonary veins.

Notes:
Vegetable and fruits should be a part of our diet because they stimulate peristalsis. Dietary fiber found in whole fresh fruits and vegetables and whole grains stimulates peristalsis, flushing out fats and waste. Gas-producing foods like broccoli and cabbage also stimulate peristalsis. Drinking plenty of fluids is important because it keeps stools soft and easy to pass.

Notes:
Animals that ingest bulk food unavoidably take in some matter that they are incapable of using. Substances that cannot be digested, such as cellulose, pass into the colon, or large intestine. Egestion is the passing out of undigested food as faeces, through the anus.

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The International Commission on Zoological Nomenclature (ICZN) was founded in 1895. It provides and regulates a uniform system of zoological nomenclature ensuring that every animal has a unique and universally accepted scientific name.

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Chlorophyll, a photo-receptive pigment, allows plants to absorb sunlight. Chlorophyll is a chlorine pigment, which is structurally similar to and produced through the same metabolic pathway as other porphyrin pigments such as heme. At the center of the chlorine ring is a magnesium ion. The molecular formula of C55H70O6N4 Mg. Hence, chlorophyll as a pigment lacks calcium.

Notes:
Lysosomes are membrane-enclosed organelles that are known as suicidal bags of the cell. They contain digestive enzymes, and break down food, cellular debris and foreign invaders like bacteria. In the event that the cell is injured beyond repair, or becomes old, the lysosome digests the cell, hence the name ‘suicide bag of the cell’.

Notes:
Dengue virus is the cause of dengue fever. Dengue virus is transmitted by female mosquitoes mainly of the species Aedes aegypti and, to a lesser extent, Ae. albopictus. This mosquito also transmits chikungunya, yellow fever and Zika infection. Dengue is widespread throughout the tropics, with local variations in risk influenced by rainfall, temperature and unplanned rapid urbanization.