General Science Questions (MCQs) for Competitive Examinations

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Fermentation is an anaerobic chemical process that breaks down glucose molecules. In baking, yeast consumes sugar and converts it into carbon dioxide and alcohol, making the dough rise. This gas gets trapped in the strands of gluten, resulting in air pockets that cause the dough to rise and form the characteristic spongy texture of bread and cakes. Further, the creation of lactic and acetic acids during fermentation augments this dough handling process, improves flavor, enhances the texture, and extends the shelf-life of the baked products.

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Sublimation describes a phase transition where a substance changes from a solid directly to a gas, bypassing the liquid state. This physical transformation is distinct from chemical changes like oxidation or reduction. Sublimation happens under certain combinations of pressure and temperature. Examples include dry ice (solid CO2), which sublimates at room temperature, and solid water, or ice, which sublimates under low pressure conditions.

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Edible seaweed products have been consumed in many Asian countries. Edible seaweeds accumulate iodine from seawater and are therefore a good dietary source of iodine. Adequate consumption of seaweed can eliminate iodine deficiency disorders, but excessive iodine intake is not good for health. The recommended dietary reference intake of 0.15 mg/d and 0.14 mg/d for iodine has been established in the United States and Taiwan, respectively. Seaweed is an excellent source of iodine. However, the amount it contains depends on the species. Kombu kelp offers the highest amount of iodine, with some varieties containing nearly 2,000% of the daily value in one gram. Seaweed is a source of iodine, necessary for thyroid function and to prevent goitre. However, an excess of iodine is suspected in the heightened cancer risk in Japanese who consume a lot of the plant, and even bigger risks in post-menopausal women.

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Pituitary gland, called Master Gland, is the smallest endocrine gland. It controls the general growth of the body coordinating the functioning of other endo crime glands and stimulates the primary sex hormones, i.e. ovaries and testes.

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Plants obtain nitrogen through their roots. In the soil, nitrifying bacteria change ammonia into nitrite (NO2 –) and then into nitrate (NO3 –), this process is known as nitrification. Furthermore, plants also absorb nitrogen in an organic form. Several organic compounds (compounds containing carbon) constitute the organic fraction of nitrogen in the soil. The organic matter in the soil exists as decomposing plant and animal residues, relatively stable decomposition-resistant compounds, and humus. The abundance of various forms of nitrogen can be altered by plant roots through the change in pH and secretion of organic compounds or oxygen.

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The small intestine, the part of the gastrointestinal tract between the stomach and the large intestine, is the main digester and absorber of food. The small intestine has three distinct regions – the duodenum, jejunum, and ileum–that carry out the absorption of nutrients and minerals from food. It converts the food into a semi-solid mass.

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The average adult has a blood volume of roughly 4-5 to 5 litres, which is composed of plasma and several kinds of cells. By volume, the red blood cells constitute about 45% of whole blood, the plasma about 54.3%, and white cells about 0.7%.

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The three organelles that contain DNA are the nucleus, mitochondria and chloroplasts. Mitochondria are unlike most organelles (with an exception of plant chloroplasts) in that they have their own set of DNA and genes that encode proteins. They are specialized structures unique to the cells of animals, plants and fungi.

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Conduction is the process by which vital nutrients are transported to the different parts of a plant. This process is independent of the light factor. Respiration process in plants is the intake of carbon-dioxide and exhales oxygen during the day as the plants gets energy through the photosynthesis process in which the carbon-dioxide is converted into sugars using the sun light energy, as this process uses carbon-dioxide and water, the resulting gas oxygen is given out as a waste product. During the night, as the photosynthesis process does not take place it exhales the carbon-dioxide itself.

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The pulmonary veins are a set of veins that deliver clean oxygenated blood from the lungs to the heart. It brings oxygen-rich blood to the left atrium. Systemic veins deliver deoxygenated blood to the heart.