General Science Questions (MCQs) for Competitive Examinations

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Endemic plants and animals are those that are unique to a specific geographic region. This makes them incredibly special and more vulnerable to extinction. Because they are only found in certain locations, they require special conservation efforts. Koalas, kangaroos, and emperor penguins are all endemic to Hawaii, Australia, and Antarctica.

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Starfish carry out movements with the help of tube feet that are part of the water vascular system. Apart from their function in locomotion, the tube feet act as accessory gills. The water vascular system serves to transport oxygen from, and carbon dioxide to, the tube feet and also nutrients from the gut to the muscles involved in locomotion.

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A pulmonary artery is an artery in the pulmonary circulation that carries deoxygenated blood from the right side of the heart to the lungs. The pulmonary arteries are unique in that unlike most arteries which carry oxygenated blood to other parts of the body, the pulmonary arteries carry de-oxygenated blood to the lungs. After picking up oxygen, the oxygen rich blood is returned to the heart via the pulmonary veins.

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Gambusia affinis, also known as Mosquito fish, is a species of freshwater fish that is introduced directly into ecosystems as a biocontrol to lower mosquito populations. The diet of this fish sometimes consists of large numbers of mosquito larvae. Gambusia affinis has turned out to be indispensable to modern Mosquito/Malaria control programs in countries such as Iran.

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The term xerophyte refers to a plant species that has evolved over time to adapt to dry and arid regions like deserts. Xerophytes have adapted to be able to keep extremely large amounts of water for a long period of time. Without this capability, the plant would die, as the desert region itself does not provide enough water to sustain life. They have thick cuticle, sunken stomata and leaves modified in form of spines such as in opuntia.

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Most of Earth’s oxygen comes from tiny ocean plants – called phytoplankton – that live near the water’s surface and drift with the currents. Like all plants, they photosynthesize – that is, they use sunlight and carbon dioxide to make food. Scientists believe that phytoplankton contribute between 50 to 85 percent of the oxygen in Earth’s atmosphere (National Geographic).

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Salt, fat and leavening agents such as yeast and baking soda are common ingredients, though bread may contain other ingredients also. Yeast plays an important role in bread-making. It ferments and grows when combined with “food” such as flour and/ or sugar, and warmed. Carbon dioxide is produced and trapped in the dough as tiny air bubbles which make the bread rise during cooking and give it its characteristic texture.

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The bamboo actually belongs to the grass family and is actually the tallest grass of all. There are kinds of bamboo which are said to grow as tall as 100 feet in height. The thickest bamboo can be 0.2m – 0.3m (8-12″) thick. Bamboo is a perennial grass with woody stems that are divided into sections by joints called nodes. One of the fastest-growing plants on the planet. However, they are known to die after flowering.

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Scurvy also once called ‘Sailor’s disease’ is a condition where an individual has a vitamin C (ascorbic acid) deficiency. Scurvy often presents itself initially as symptoms of malaise and lethargy, followed by formation of spots on the skin, spongy gums, and bleeding from the mucous membranes. Spots are most abundant on the thighs and legs, and a person with the ailment looks pale, feels depressed, and is partially immobilized. As scurvy advances, there can be open, suppurating wounds, loss of teeth, jaundice, fever, neuropathy and death.

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DNA, or deoxyribonucleic acid, is the hereditary material in humans and almost all other organisms. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA) . Mitochondria are structures within cells that convert the energy from food into a form that cells can use. The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T).