General Science Questions (MCQs) for Competitive Examinations

Notes:
There are three tiny bones in the middle ear of human. These are the malleus or hammer the incus or anvil and the stapes or stirrup. The femur is the only bone located within the human thigh. It is both the longest and the strongest bone in the human body.

Notes:
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.

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A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.

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The structure of B12 is based on a corrin ring, which is similar to the porphyrin ring found in heme, chlorophyll, and cytochrome. It contains the biochemically rare element cobalt sitting in the centre of the ring. Also called cobalamin, it is a water-soluble vitamin.

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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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Although sea stars (star fish) are benthoic i.e. live underwater and are commonly called “starfish,” yet they are not fish. They belong to phylum Echinodermata whose members are exclusively marine and benthsoc with great power of repeneration are characterized by water vascular system.

Notes:
In eukaryotic (with nucleus) cells, the vast majority of DNA is found in the nucleus as discrete bodies called chromosomes. The exception to this being the small amount of DNA found in organdies outside the nucleus (mitochondria and chloroplasts). In human cells, more than 99% of the total DNA is nuclear genomic DNA and the remainder mitochondrial.

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In order for the cell cytoplasm to communicate with the external environment, materials must be able to move through the plasma membrane. Osmosis is the movement of water from a region of higher concentration to one of lower concentration. Osmosis occurs across a membrane that is semipermeable.

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Triploblasty is a condition of the blastula in which there are three primary germ layers: the ectoderm, mesoderm, and endoderm. The germ layers form during gastrulation of the blastula. All “higher” and “intermediate animals” (from flat worms to humans), arise from a triploblastic ovum. Triploblastic organisms generally possess bilateral symmetry.

Notes:
Bariatric surgical procedures cause weight loss by restricting the amount of food the stomach can hold, causing malabsorption of nutrients, or by a combination of both gastric restriction and malabsorption. The most common bariatric surgery procedures are gastric bypass, sleeve gastrectomy, adjustable gastric band, and biliopancreatic diversion with duodenal switch. Gastric bypass and other weight-loss surgeries make changes to digestive system.