Biology MCQs

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When cells are exposed to sunlight, radiant energy can damage the DNA. For example, ultraviolet irradiation causes covalent bond formation between adjacent thymines on the same strand of DNA.

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Parietal cells (also known as oxyntic cells), are the epithelial cells that secrete hydrochloric acid (HCl) and intrinsic factor. These cells are located in the gastric glands found in the stomach. They contain an extensive secretory network from which the HCl is secreted by active transport into the stomach.

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A respiratory pigment is a molecule, such as haemoglobin in humans, that increases the oxygen carrying capacity of the blood. The four most common invertebrate respiratory pigments are haemoglobin, haemocyanin, haemerythrin and chlorocruorin.

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Haptens are small molecules that react with a specific antibody but cannot induce the formation of antibodies unless bound to a carrier protein or other large antigenic molecule. They are incomplete or partial antigens.

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Micropropagation is the practice of rapidly multiplying stock plant material to produce a large number of progeny plants, using modern plant tissue culture methods. It leads to the production of plants that are clones of each other. It often produces more robust plants, leading to accelerated growth compared to similar plants produced by conventional methods– like cuttings.

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A vein is an elastic blood vessel that transports blood from various regions of the body to the heart. Veins are components of the cardiovascular system, which circulates blood to provide nutrients to the cells of the body. Veins can be categorized into four main types: pulmonary, systemic, superficial, and deep veins.

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A vector-borne disease is one in which the pathogenic microorganism is transmitted from an infected individual to healthy individual by an arthropod or other agent, sometimes with other animals serving as intermediary hosts. The transmission depends upon the attributes and requirements of at least three different living organisms: the pathogenic agent, either a virus, protozoa, bacteria, or helminth (worm); the vector, which are commonly arthropods such as ticks or mosquitoes; and the human host.

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The term Blattaria comes from the Latin blatta, which simply means cockroach. It is the scientific name of cockroaches and refer to an order of medium to large-sized broadly oval flattened cursorial cockroaches.

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Nitrogen is the most plentiful gas in the air. When we inhale, we take some amount of nitrogen into our lungs and exhale it. But plants need nitrogen for their survival. They cannot take nitrogen directly from the air. Bacteria, that live in the soil and roots of some plants, take nitrogen from the air and change its form so that plants can use it.

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The levels of thermal tolerance of different species determine to a large extent their geographical distribution. A few organisms that can tolerate and thrive in a wide range of temperatures are called eurythermal but, a vast majority of them are restricted to a narrow range of temperatures, such organisms are called stenothermal.