Biology MCQs

Notes:
Most cases of filariasis are caused by the parasite known as Wuchereria bancrofti. A wide range of mosquitoes can transmit this parasite, depending on the geographic area. In Africa, the most common vector is Anopheles while in the Americas, it is Culex quinquefasciatus. Aedes and Mansonia transmits transmit the infection in the Pacific and in Asia. Thus, Culex, Aedes and Anopheles mosquitoes serve as vector for W. bancrofti in transmission of the disease. Aedes mosquito causes dengue fever. Anopheles mosquito causes malaria. Culex mosquito causes filaria. A wide range of mosquitoes can transmit the parasite, depending on the geographic area. In Africa, the most common vector is Anopheles and in the Americas, it is Culex quinquefasciatus. [This question was wrongly framed in exam as “filaria is caused by__:”. GKtoday has edited it to make it correct.]

Notes:
The right pulmonary artery is longer and larger and runs horizontally outward in front of right main bronchus and behind the superior vena cava, to the base of the right lung where it divides in two branches. The left pulmonary artery is shorter and runs horizontally over the left upper division bronchus, to the base of the left hilum where it divides into two branches.

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The morphology of the chromosomes can be distinctly studied at metaphase stage of cell division because at this stage chromosomes are in highly condensed state (25 times of orginal size) and become thicker and well arranged.

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Both polio and chicken pox are caused by virus. Poliomyelitis, often called polio or infantile paralysis, is an infectious disease caused by the poliovirus; while, Chickenpox, also known as varicella, is a highly contagious disease caused by the initial infection with varicella zoster virus (VZV).

Notes:
The pigment that gives human skin, hair, and eyes their color. Dark-skinned people have more melanin in their skin than light-skinned people have. Melanin is produced by cells called melanocytes. Everyone has the same number of melanocytes, but some people make more melanin than others.

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Small intestine has three parts – duodenum, jejunum, and ileum. The maximum digestion of food takes place in the duodenum. While the digestion of food is completed in jejunum. The maximum absorption of food takes place in ileum.

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A biomass is total quantity of weight of the planet that can be classified according to the plants and animals that live in it. Temperature, soil, and the amount of light and water help determine what life exists in a biome.

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Oxygen is one of several dissolved gases important to aquatic systems. Dissolved oxygen is necessary to maintain aerobic conditions in surface waters and is considered a primary indicator when assessing the suitability of surface waters to support aquatic life. Dissolved oxygen can be measured in two ways: either in milligrams per litre (mg/L) or percent saturation (% sat). Water with an oxygen concentration of less than 3 mg/L will generally not support fish. When concentrations fall to about 3-4 mg/L, fish start gasping for air at the surface or huddle around the water fall (higher concentration points). Above 5 mg/L, almost all aquatic organisms can survive indefinitely, provided other environmental parameters are present within allowable limits.

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Vitamin A deficiency results in night blindness, the inability or reduced ability to see in dim light or darkness. Also known as nyctalopia, night blindness is due to a disorder of the cells in the retina that are responsible for vision in dim light which is caused by Vitamin A deficiency.

Notes:
Sea hares are molluscs. They belong to Phylum Mollusca and Class Gastropoda like snails. Like many other sea slugs (Subclass Opistobranchia), sea hares lack external shells as adults. Sea hares belong to Order Anaspidea.