Biology MCQs

Notes:
Blood Pressure is expressed in two numbers. The higher number is known as Systolic Pressure, or the amount of force (as measured in millimetres of mercury) that is exerted against the artery walls during a heartbeat (contraction). The lower number in the Diastolic pressure, which does the force exist while the heart is resting between beats.

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Pearls are composed primarily of calcium carbonate, which is what gives them their unique luster. They are formed within the shell of certain mollusks as a defense mechanism against a potentially threatening irritant, such as a parasite. Over time, the mollusk continually deposits layers of calcium carbonate, which eventually forms a smooth, hard pearl. This process can take up to eight years.

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The colonization of an area that has not been previously occupied by an ecological community is called primary succession. Examples are: newly exposed rock or sand surfaces, lava flows, newly exposed glacial tills, etc.

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The radiations used in Radiotherapy for the treatment of Cancer destroys the Cancer tumour mainly by Destroying the DNA of the Cancerous Cells. It uses high doses of radiation to kill cancer cells and shrink tumors.

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Azolla, also known as mosquito fern, is used as a biofertilizer because it has a symbiotic relationship with nitrogen-fixing cyanobacteria. The cyanobacteria, Anabaena azollae, lives on the leaves of Azolla and can fix atmospheric nitrogen. This nitrogen-fixing ability increases the fertility of the soil and enhances crop yields.
Azolla is a small aquatic fern that grows on the surface of water or moist soil. It is used as a biofertilizer for rice in Asia. Azolla can be grown as a green manure before transplanting rice or as an intercrop with the rice. Both practices are reported to increase the growth and yield of rice.
Azolla is also used as animal feed, human food, medicine, and water purifier.

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Sexual reproduction in flowering plants involves the production of male and female gametes, the transfer of the male gametes to the female ovules in a process called pollination. After pollination occurs, fertilization happens and the ovules grow into seeds within a fruit.

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Stigma of the plant is used in making the saffron spices. In making the saffron spice, stigma of the plant is used. Stigma is the top of the centre part of a flower. It receives the pollen that allows it to form new seeds.

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The connective tissues include several types of fibrous tissue that vary only in their density and cellularity, as well as the more specialized and recognizable variants—bone, ligaments, tendons, cartilage, and adipose tissue. Skin is not a connective tissue. It is the body’s largest organ and consists of multiple layers, including the epidermis (outermost layer) and the dermis (deeper layer). Skin primarily serves as a protective barrier and regulates temperature, but it is mainly classified as an epithelial tissue due to its structure and function.

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There are two types of bone marrow: red marrow (also known as myeloid tissue) and yellow marrow. Red blood cells, platelets and most white blood cells arise in red marrow; some white blood cells develop in yellow marrow.

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Alpha-keratin, or α-keratin, is a type of keratin found in vertebrates. This protein is the primary component in hair, horns, mammalian claws, nails and the epidermis layer of the skin. α-keratin is a fibrous structural protein, meaning it is made up of amino acids that form a repeating secondary structure.