General Science Questions (MCQs) for Competitive Examinations

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The mitochondria is called the powerhouse of the cell because it is responsible for producing most of the cell’s energy, or adenosine tri-phosphate (ATP). In addition to supplying cellular energy, mitochondria are involved in other tasks, such as signaling, cellular differentiation, and cell death, as well as maintaining control of the cell cycle and cell growth.

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The red, orange and yellow colours of leaf are due to carotenoids contained in chromoplasts. When the green chlorophyll in leaves diminishes, the yellow pigments that already exist become dominant and give their color to the leaves.

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Heart rate is the speed of the heartbeat measured by the number of contractions of the heart per minute (bpm). Conventionally, a normal adult has a heartbeat rate of 72 per minute. However, the heart rate can vary according to the body’s physical needs, including the need to absorb oxygen and excrete carbon dioxide.

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Virology is the branch of science that deals with the study of viruses. It focuses on the following aspects of viruses: their structure, classification and evolution, their ways to infect and exploit host cells for reproduction, their interaction with host organism physiology and immunity, the diseases they cause, and their use in research and therapy.

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HIV’s enzyme for inserting the DNA version of its genome into the host cell DNA is called its “integrase”. HIV-1 integrase catalyzes the “cut-and-paste” action of clipping the host DNA and joining the proviral genome to the clipped ends. It is also produced by viruses containing double-stranded DNAs for the same purpose.

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Conglobate gland is a leaf like, median, unbranched gland of male cockroach. It lies below the ejaculatory duct and open into the genital pouch close to the male genital aperture.

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Leishmaniasis (Kala azar) is a disease spread by the bite of the female sandfly. The disease is the second-largest parasitic killer in the world (after malaria). The parasite migrates to the internal organs such as liver, spleen (hence ‘visceral’), and bone marrow, and, if left untreated, will almost always result in the death of the host.

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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.

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Glycolysis is the first of the main metabolic pathways of cellular respiration to produce energy in the form of ATP. Through two distinct phases, the six-carbon ring of glucose is cleaved into two three-carbon sugars of pyruvate through a series of enzymatic reactions. Overall, the process of glycolysis produces a net gain of two pyruvate molecules, two ATP molecules, and two NADH molecules for the cell to use for energy.

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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.