General Science Questions (MCQs) for Competitive Examinations

Notes:
Carbon monoxide (CO) is considered a pollutant since it is toxic to haemoglobic animals (including humans) when encountered in concentrations above about 35 ppm. It combines with haemoglobin to produce carboxy-haemoglobin, which usurps the space in haemoglobin that normally carries oxygen, but is ineffective for delivering oxygen to bodily tissues. HGB with 250 times attinity to carbon monoxides as compared to oxygen is toxic. A level of 50% carboxy-haemoglobin may result in seizure, coma, and fatality.

Notes:
Bariatric surgical procedures cause weight loss by restricting the amount of food the stomach can hold, causing malabsorption of nutrients, or by a combination of both gastric restriction and malabsorption. The most common bariatric surgery procedures are gastric bypass, sleeve gastrectomy, adjustable gastric band, and biliopancreatic diversion with duodenal switch. Gastric bypass and other weight-loss surgeries make changes to digestive system.

Notes:
Starfish carry out movements with the help of tube feet that are part of the water vascular system. Apart from their function in locomotion, the tube feet act as accessory gills. The water vascular system serves to transport oxygen from, and carbon dioxide to, the tube feet and also nutrients from the gut to the muscles involved in locomotion.

Notes:
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.

Notes:
Red Blood Corpuscles (RBCs) do not contain mitochondria when matured. These are the site of aerobic respiration. They they also lack the oxidative enzymes that are required for aerobic respiration. For this reason, Embden-Meyerhof pathway is used to process glucose and thus obtain energy. This is an anaerobic energy producing process that has been shown to use glycogen in the absence of glucose.

Notes:
An analgesic or painkiller is any member of the group of drugs used to achieve analgesia, relief from pain. Analgesic drugs act in various ways on the peripheral and central nervous systems. They are distinct from anaesthetics, which temporarily affect, and in some instances completely eliminate, sensation.

Notes:
Methane (CH4) is a greenhouse gas and causes warming the same way that CO2 does. It absorbs radiation emitted from the surface and re-emits that radiation in all directions with some of the radiation returning to the surface where it is absorbed and converted to heat. In the first two decades after its release, methane is 84 times more potent than carbon dioxide.

Notes:
The main source of atmospheric free oxygen is photosynthesis, which produces sugars and free oxygen from carbon dioxide and water. The organisms that carry out photosynthesis include the plant life of the land areas as well as the phytoplankton of the oceans.
6CO2 + 6H2O + energy —> C6H12O6 + 6O2

Notes:
Bird and snake excretory product is uric acid. Nitrogenous waste is excreted in form of ammonia. In birds and reptiles, uric acid is the major end-product of protein metabolism. It is produced by the liver and excreted by kidney tubules; impaired elimination is an indication of renal disease.

Notes:
The majority of the upper respiratory epithelium is lined with cilia, small hair-like structures that move together like oars to push the mucus and its trapped contents to the throat, where it is swallowed. Each cell has about 300 cilia.