General Science Questions (MCQs) for Competitive Examinations

Notes:
Magnetite (Fe3O4) typically contains about 70% iron by weight. It is black in color and strongly magnetic. Hematite (Fe2O3) contains about 60–70% iron. Limonite contains 35–50% iron. Siderite (FeCO3) contains about 48% iron. Magnetite is widely mined due to its high iron concentration compared to other ores.

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Lysosomes are called the suicide bags of the cells they contain digestive enzymes, and break down food, cellular debris and foreign invaders like bacteria. When the cell is injured beyond repair, or becomes old, the lysosome digests the cell. So, it is called “suicide bag of the cell.”

Notes:
Insulin is central to regulating carbohydrate and fat metabolism in the body. It stops the use of fat as an energy source by inhibiting the release of glucagon. It removes excess glucose from the blood, which otherwise would be toxic. Insulin helps blood sugar enter the body’s cells so it can be used for energy. Insulin also signals the liver to store blood sugar for later use. Blood sugar enters cells, and levels in the bloodstream decrease, signaling insulin to decrease too.

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Cyanobacteria, also known as blue green algae, are single-celled and belong to the family of Prokaryotes. That means, they do not have a well defined cell nucleus. The ability of cyanobacteria to perform oxygenic photosynthesis is thought to have converted the early reducing atmosphere into an oxidizing one, which dramatically changed the composition of life forms on Earth by stimulating biodiversity and leading to the near-extinction of oxygen-intolerant organisms.

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Based on the dividing capacity of the tissues, various plant tissues can be classified as growing or meristematic tissue and permanent tissue. Meristem is a type of tissue system in plants, composed of a mass of undifferentiated cells and their primary function is to take part in the growth of plants. Permanent tissues are differentiated tissues doing specific functions such as conduction, providing mechanical support or carrying out photosynthesis etc.

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The three organelles that contain DNA are the nucleus, mitochondria and chloroplasts. Mitochondria are unlike most organelles (with an exception of plant chloroplasts) in that they have their own set of DNA and genes that encode proteins. They are specialized structures unique to the cells of animals, plants and fungi.

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Vermicomposting is the process of using worms also called red worms and micro-organisms to turn kitchen waste into black, earthy-smelling, nutrient-rich humus. Vermicompost is an excellent, nutrient-rich organic fertilizer and soil conditioner.

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Bacteria are the most abundant organisms which play important role in the decomposition of organic matter. Majority of bacteria involved in decomposition of organic matter are heterotrophs and autotrophs are least in proportion which are not directly involved in organic matter decomposition.

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The masseter is located in the jaw and is one of the muscles of mastication or chewing. ? The bite strength of an average man is between 117 to 265 pounds. ? This ability to exert a force on an external object is an example of absolute strength.

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Bharat Biotech, a vaccine company, in December 2017, received Pre-Qualification tag from the World Health Organisation (WHO) for Typbar TCV or Typhoid Conjugate Vaccine. The WHO tag would allow the firm to access global public vaccination programmes. Typbar TCV is the first typhoid vaccine, clinically proven to be administered to children from six months of age to adults and confers long term protection against typhoid fever.