Biology MCQs

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A hormone, which is released by the posterior pituitary is Oxytocin. The posterior pituitary does not synthesize hormones, but it is able to store and release the two hormones.

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A polymerase chain reaction is a chemical reaction used by molecular biologists to amplify fragments of DNA.

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Order is an assemblage of families which exhibit a few similar characters. The similar characters are less in number as compared to different genera included in a family. A class includes one or more orders.

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The principal chemical component of vegetable fibres is cellulose, with varying amounts of lignin and hemicelluloses also usually present; thus, the fibres are also referred to as cellulosic or lignocellulosic. Examples include cotton, hemp, jute, flax, ramie, sisal, bagasse, and banana. Vegetable fibres are usually stiffer but less tough than synthetic fibres.

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The term fish is most strictly used to describe any animal with a backbone that has gills throughout life and has limbs, if any, in the shape of fins. Many types of aquatic animals commonly referred to as fish are not fish in this strict sense; examples include shellfish, cuttlefish, starfish, crayfish and jellyfish.

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Interferons (IFNs) are a group of signaling proteins made and released by host cells in response to the presence of pathogens, such as viruses, bacteria, parasites, or tumor cells. Interferon synthesis occurs primarily in response to viral single-stranded or double stranded RNA that are either the genetic material of RNA viruses or a product of viral transcription. Interferons are named for their ability to “interfere” with viral replication by protecting cells from virus infections.

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Carbon monoxide (CO) reduces the oxygen carrying capacity of blood. This is because it has a larger affinity towards haemoglobin than oxygen. Haemoglobin is responsible for circulating oxygen. Hence, in the presence of carbon monoxide the haemoglobin bonds with it to form carboxy-haemoglobin rather than the oxygen and hence reduces the oxygen carrying capacity of blood.

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Brailing is the practice of preventing a bird from flying by tying the wing so that it is impossible for the bird to open wings fully and fly. The brail is a clear plastic strap, fastened by rivets, which will be used to restrain his wing. Brailing the birds helps prevent injuries during shipment.

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An allosome is a sex chromosome that differs from an ordinary autosome in form, size, or behaviour. The human sex chromosomes are a typical pair of allosomes. In typical ovum, there is a pair of X-chromosomes while sperm has X and Y chromosome each.

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Robert Hooke, a scientist, was the first person to discover the existence of cells with the help of a microscope in 1665. Anton van Leeuwenhoek, in 1674 with the improved microscope, discovered freeliving cells of algae Spirogyra in pond water for the first time. He described the algae Spirogyra and also saw bacteria.