Biology MCQs

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Animal cells do not have cell walls. Cell walls are found in plant cells. Other given organelles like Mitochondria, Ribosome and Cytoplasm are present in animal cells.

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Amnesia refers to a loss of memory due to illness, injury, drug abuse or other causes.

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Thrombin is a naturally occurring enzyme that converts fibrinogen into fibrin, which is an integral step in clot formation. Ca2+ is essential for both activation and action of thrombin.

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Sucralose is an artificial sweetener. The majority of ingested sucralose is not broken down by the body and therefore it is non-caloric. Sucralose is approximately 600 times as sweet as sucrose (table sugar), twice as sweet as saccharin, and 3 times as sweet as aspartame. It is stable under heat and over a broad range of pH conditions. Therefore, it can be used in baking or in products that require a longer shelf life. The commercial success of sucralose-based products stems from its favorable comparison to other low-calorie sweeteners in terms of taste, stability, and safety. It is used because it is a no-calorie sweetener, and does not promote dental cavities, is safe for consumption by diabetics, and does not affect insulin levels.

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The breathing rate is controlled by the medulla in the brain, which is primarily sensitive to CO₂ levels in the blood.

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Urea is a nitrogenous waste that is produced in the liver; urine is produced in the kidney. We note here that Uric acid is excreted as a crystal to conserve water by many terrestrial animals. However, humans and earthworms release nitrogenous waste in the form of urea.

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The Plasmodium parasite that causes malaria is neither a virus nor a bacterium – it is a single-celled parasite that multiplies in red blood cells of humans as well as in the mosquito intestine. When the female mosquito feeds on an infected person, male and female forms of the parasite are ingested from human blood.

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Withering is used to remove excess water from the leaves and allows a very slight amount of oxidation. The process is also important in promoting the breakdown of leaf proteins into free amino acids and increase the availability of freed caffeine, both which change the taste of the tea.

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The theory of origin of life on earth is proposed by Haldane. Further this theory was confirmed by the experiments conducted by Stanley L. Miller and Harold C. Urey.

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Cereals which are made with puffed or powdered rice and refined wheat typically contain starch. Starch is the most common form of carbohydrate and typically found in staple grains like rice, wheat, and corn.