Biology MCQs

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Lymphocytes are a type of white blood cell that are part of the immune system. Their main function is to produce antibodies that protect the body from foreign invaders, such as viruses, bacteria, and toxins. These antibodies help the body respond to and eliminate foreign invaders, which provides protection against infectious diseases.
Lymphocytes also help the body’s immune system remember every antigen it comes in contact with. After an encounter, some lymphocytes turn into memory cells.
There are two main types of lymphocytes: B cells and T cells. B cells produce antibodies that attack invading bacteria, viruses, and toxins. T cells destroy the body’s own cells that have been taken over.
If you have low numbers of lymphocytes (lymphopenia), you are at higher risk of infection. Symptoms can range from mild to serious and are correlated to the severity of the lymphopenia as well as its duration. Some people have no symptoms.

Notes:
When red blood cells are placed in distilled water, the water molecules move into the cells by osmosis because the cells have a higher solute concentration than the distilled water. This influx of water causes the red blood cells to swell and eventually burst in a process known as hemolysis. This demonstrates how osmosis, a vital biological process, can result in cell damage when the external conditions are not balanced.

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Oleic Acid is not a vitamin. It is a fatty acid which occurs naturally in various animal and vegetable fats and oils. It is an odorless, colorless oil, however commercial samples may be yellowish.

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Lysosomes are membrane-bound cell organelles that contains digestive enzymes and are involved with various cell processes. They break down excess or worn-out cell parts and may be used to destroy invading viruses and bacteria.

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Cornea does not have blood vessels. It is the transparent part of the eye that covers the front portion of the eye. It covers the pupil, iris, and anterior chamber.

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Thymine is the nitrogenous base that is present in DNA but not in RNA. Thymine is a pyrimidine base that pairs with adenine through hydrogen bonding in DNA. In RNA, thymine is replaced with uracil, which pairs with adenine.
The four nitrogenous bases in DNA are adenine, guanine, cytosine, and thymine. The four nitrogenous bases in RNA are adenine, cytosine, guanine, and uracil.

Notes:
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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Cleviceps purpurea is an important ascomycete that grows on the grains of rye grass cereals. It produces the drug ergot, which is both a severe poison and a useful medicinal drug. It affects the central nervous system as well as causes the contraction of involuntary muscle. Ergotism, caused by eating infected rye bread, was common in the Middle Ages, when it was known as “St. Anthony’s Fire.

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Actinobiolgy is the branch of biology which studies the effects of radiation on organisms.  Cryobiology involves study of life at Low temperatures; Cytogenetics involves  Cytological basis of inheritance and Aerobiology deals with the studies of spores and micro organisms in air.