General Science Questions (MCQs) for Competitive Examinations

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Branch roots are of two kinds: long-branching geotropic roots and short-branching apogeotropic roots, which are referred to as coralloid because of their irregular, beady appearance. The coralloid roots contain symbiotic cyanobacteria (blue-green algae), which fix nitrogen. It also collects water and soil nutrients and store carbohydrates.

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Green is the least effective color of light in driving photosynthesis, the process of converting light energy into chemical energy. Photosynthesis occurs in plants and algae using chlorophyll, and because chlorophyll reflects rather than absorbs green light, green light cannot be used in the photosynthetic process.

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The nephron is the basic structural and functional unit of the kidney. Its chief function is to regulate the concentration of water and soluble substances like sodium salts by filtering the blood, reabsorbing what is needed and excreting the rest as urine.

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Plague is caused by bacteria. It is a deadly infectious disease caused by the enterobacteria Yersinia pestis, named after the French-Swiss bacteriologist Alexander Yersin. It has led to death of million of people at one time.

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The richest sources of protein are animal foods such as chicken, meat, fish, cheese and eggs. However, plant proteins are believed to be healthier because of their lower fat content. Plant protein is found (e.g.) in beans (esp. soy beans), lentils, nuts, quorn and seeds. Fish and seafood are some of the richest sources of protein. Soybeans are legumes that provide a valuable protein-rich food option for vegetarians and non-vegetarians alike. One cup of boiled soybeans provides over 28g of protein.

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Capra Hircus is the scientific name of domestic goat or simply goat. It is a subspecies of C. aegagrus domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the animal family Bovidae and is closely related to the sheep; both are placed in the goat-antelope subfamily Caprinae.

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The guard cells in dicot plants are kidney shaped and dumbbell shaped in monocots. When guard cells expand on the outer edges of the stoma, but not on the inner side, they result in kidney-shaped cells, leading to an opening or pore between the two guard cells for gas exchange.

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Root hairs are tubular-shaped tip-growing cells that arise from epidermal cells known as trichoblasts, behind the tips of young roots. Like all tip-growing cells, root hairs grow by the addition of cell wall precursors to the tip delivered by vesicles from the endomembrane system.

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Chloroplast, found in plant cells, is the site of photosynthesis in plants to prepare food(glucose) for the plant with the use of energy. It is a green plastid that contains chlorophylls A and B that absorb visible light energy and convert it to usable chemical energy in photosynthesis.

Notes:
Breathing is the process in which air moves in and out of the lungs with the help of various respiratory organs. The process of taking in air rich in oxygen is called inhalation. Similarly, the process of giving out air rich in carbon dioxide is called exhalation. When we inhale, the ribs move up and outwards while the diaphragm moves down. An exact opposite movement occurs during exhalation when the ribs move down and inwards while the diaphragm moves up.