Daily Quiz: UPSC Prelims Marathon – December 27, 2018

Air is a homogeneous mixture. However, the Earth’s atmosphere as a whole is a heterogeneous mixture.

Clouds are mixture of air and water molecules. That’s evidence the composition is not uniform. Alloys are made when two or more metals are mixed together. They usually are homogeneous mixtures.

Examples include brass, bronze, steel, and sterling silver. Sometimes multiple phases exist in alloys. In these cases, they are heterogeneous mixtures. The two types of mixtures are distinguished by the size of the crystals that are present. A homogeneous mixture can be a component of a heterogeneous mixture. For example, bitumen (a homogeneous mixture) is a component of asphalt (a heterogeneous mixture).

Statement 3 is incorrect. In photosynthesis, sugar is made by using carbon dioxide and water. Statement 1 and 2 are correct. Photosynthesis is the process by which plants, some bacteria and some protistans use the energy from sunlight to produce glucose from carbon dioxide and water. This glucose can be converted into pyruvate which releases adenosine triphosphate (ATP) by cellular respiration. Oxygen is also formed. For most plants, rate of photosynthesis does not increase at higher temperatures. Fall in rate of photosynthesis takes place when temperature rises above 40 degree.

The organisms, which depend on other organisms for their food, are called heterotrophs and their mode of nutrition is heterotrophic nutrition. Heterotrophic nutrition is of various types

(i) Holozoic nutrition: Holozoic nutrition includes ingestion, digestion and absorption of food as in Amoeba, frogs and human beings.

(ii) Parasitic nutrition: Have you ever been bitten by a head louse or a bed bug or had worms inside the body? These organisms that live on or inside other living organisms, and derive their food from them are called parasites and the nutrition is called parasitic nutrition. Cuscuta or Dodder plant (Amar bel) is a parasite on green plants.

(iii) Saprotrophic nutrition: You must have seen a white cottony growth developing on your wet leather shoes or belts especially when they get wet during rainy days. This is a fungus. The fungus grows and feeds on substances, which were once part of the living organisms, such as stored food, wood, leather and rotten plant products. Some common examples are mushrooms, bread mould, yeast, etc. Organisms that derive their food from dead and decaying organisms are called saprotrophs. Saprotrophs help in cleaning the environment by decomposing the dead and decaying organic matter.

Both the statement are correct. Important note: The United States believes the Syrian government employed a sarin-like nerve agent in recent deadly attack in the country’s northwest. The name sarin comes from the chemists who discovered it by chance: Schrader, Ambros, Ruediger et Van der Linde. Originally conceived as a pesticide, sarin was used by Iraqi dictator Saddam Hussein’s regime to gas thousands of Kurds in the northern town of Halabja in 1988. Inhaled or absorbed through the skin, the gas kills by crippling the respiratory center of the central nervous system and paralysing the muscles around the lungs. The combination results in death by suffocation, and sarin can contaminate food or water supplies, according to the US Centers for Disease Control and Prevention (CDC). Symptoms of exposure to the agent include nausea and violent headaches, blurred vision, drooling, muscle convulsions, respiratory arrest and loss of consciousness. Sarin is 26 times more deadly than cyanide gas. Even when it does not kill, sarin’s effects can cause permanent harm —damaging a victim’s lungs, eyes and central nervous system.

All are correctly matched

• An asteroid is a celestial body – composed of rock, metal or a mixture of both – that is orbiting the Sun. Most of them are in the asteroid belt between Mars and Jupiter. Even though there are millions of asteroids with sizes up to more than 500 km (like Pallas and Vesta) they are of no danger to the planet Earth. The biggest body in the asteroid belt – Ceres – is officially not called an asteroid anymore but a dwarf planet.
• Comet- A smaller celestial body mainly composed of ice and dust. If a comet approaches the Sun it can generate a tail of gas and/or dust.
• Meteor- A bright tail of light caused by a meteoroid during its atmospheric flight, also called a shooting star or falling star.

India is collaborating with Russia to build Rooppur nuclear power plant in Bangladesh. It will be first initiative under an India-Russia nuclear deal to undertake atomic energy projects in third countries. It will also be India’s first atomic energy venture abroad. Rooppur Nuclear project (capacity of 2*1200 MWs) is Bangladesh’s first atomic energy project. It is being built with Russia’s help near Dhaka. After commissioning of two units each with capacity of 1200 MWs, Bangladesh will be third South Asian country after India and Pakistan to harness atomic energy for energy purpose.

Asteroids are composed mainly of rock and metals, while comets are made of ice, dust and small rocks. An object becomes a meteor if it enters Earth’s atmosphere. Since meteors leave visible streaks across the sky, they are often known as shooting stars. The term “meteorite” refers to solid debris that survives entry and impact with the ground.