FC-for-IAS-Prelims-2018-revision-Day-38
70 Days WAR Plan

DAY#38 Static Flash Cards General Science [70 Days WAR Plan]

Quasars; ‘Photoperiodism’, ‘Chronobiology’, ‘Bioluminescence’ and ‘Scotobiology’; Tooth decay; Potential applications of Graphene; Microwave ovens; Liver; Disorders of the circulatory system; Parkinson’s disease; Generation and conduction of nerve impulse; Aqua regia;
By IT's Core Team
April 28, 2019

 

 

 

What are Quasars? and which is the most powerful Quasars?

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Answer & Enrich Your Learning:

  • Quasars are so bright and can be seen all the way across the universe. This makes them the ideal objects to use to make the biggest map yet.
  • The most powerful quasars have luminosities exceeding 1041 W, thousands of times greater than the luminosity of a large galaxy such as the Milky Way.
  • These are the bright and distant points of light powered by super-massive black holes.
  • The brightness of quasars is due to the supermassive black holes found at their centres.
  • Visible light, ultraviolet rays, infrared waves, X-rays, and gamma-rays are emitted by these objects.
  • Astronomers have created the first map of the large-scale structure of the universe based entirely on the positions of quasars.
  • Quasars are believed to produce their energy from massive black holes in the center of the galaxies in which the quasars are located.
  • A pulsar (short for pulsating radio star) is a highly magnetized, rotating neutron star that emits a beam of electromagnetic radiation.
  • Brown dwarfs are objects which are too large to be called planets and too small to be stars. They have masses that range between twice the mass of Jupiter and the lower mass limit for nuclear reactions (0.08 times the mass of our sun).
  • Dark nebulae are interstellar clouds that contain a very high concentration of dust. This allows them to scatter and absorb all incident optical light, making them completely opaque at visible wavelengths.

 

 

 

With reference to chemistry, what does the term Aqua regia refer to?

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Answer & Enrich Your Learning:

  • Aqua regia is a freshly prepared mixture of concentrated hydrochloric acid and nitric acid in the ratio of 3:1.
  • It is a highly corrosive, fuming liquid, which can dissolve gold, even though neither of the acids can do so alone.
  • It is one of the few reagents that is able to dissolve gold and platinum. But, it can’t dissolve all metal; such as, iridium and tantalum.
  • Chloroauric acid may be made by using aqua regia to produce electrolytes for the Wohlwill process. This process refines gold to extremely high purity (99.999%).
  • A similar process is used to produce high-purity platinum.
  • Aqua regia is used to etch metals and for analytic chemical analysis. The acid is used to clean metals and organics from machines and laboratory glassware.

 

 

 

Which ions are responsible for generation and conduction of nerve impulse?

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Answer & Enrich Your Learning:

  • Neurons are excitable cells because their membranes are in a polarised state. Different types of ion channels are present on the neural membrane. These ion channels are selectively permeable to different ions.
  • When a neuron is not conducting any impulse, i.e., resting, the axonal membrane is comparatively more permeable to potassium ions (K+) and nearly impermeable to sodium ions (Na+).
  • The membrane is impermeable to negatively charged proteins present in the axoplasm. Consequently, the axoplasm inside the axon contains high concentration of K+and negatively charged proteins and low concentration of Na+.
  • In contrast, the fluid outside the axon contains a low concentration of K+, a high concentration of Na+ and thus form a concentration gradient.
  • Sodium ions are tenfold higher in concentration outside than inside the membrane surface, whereas potassium ions are twenty times more concentrated inside than outside.
  • All the neurons have very active sodium and potassium pumps located in their cell membranes.
  • Driven by the splitting of ATP, these pumps transport Na+out and K+ into the cell, both against their respective concentration gradients.
  • For every two K+ions that are actively transported, inward, three Na+ ions are pumped out. So inside becomes more negative than outside of the cell membrane of neurons. 
  • Charges that occur along the length of neuron till the impulse reaches synapse. Soon after the passage of the impulse, the resting membrane potential is restored by the movement of a small number of ions especially K+ moving out. This neuron is ready to conduct another impulse.
  • It may be added that in myelinated neurons the impulse jumps from node to node (node of Ranvier). This is called Saltatory impulse.

 

 

 

What is Parkinson’s disease?

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Answer & Enrich Your Learning:

  • Potential graphene applications include lightweight, thin, flexible, yet durable display screens, electric/photonics circuits, solar cells, and various medical, chemical and industrial processes enhanced or enabled by the use of new graphene materials.
  • The potential applications of grapheme also include water filtration and purification, renewable energy, sensors, personalised healthcare and medicine, to name a few.
  • Because of its strength, electrical conductivity and elasticity, Graphene been seen as an alternative to lithium-ion batteries since its discovery in 2004.
  • It is a form of carbon that can be used to develop smaller, slimmer batteries but with higher capacity. Graphene is a carbon material that is one atom thick. Its thin composition and high conductivity means it is used in applications ranging from miniaturized electronics to biomedical devices.
  • These properties also enable thinner wire connections; providing extensive benefits for computers, solar panels, batteries, sensors and other devices.
  • Graphene has excellent electronic, mechanical, thermal and optical properties as well. Its uses range from improving battery performance in energy devices, to cheaper solar panels.
  • Graphene produced by exfoliation was one of the most expensive materials on Earth, with a sample the area of a cross section of a human hair costing more than $1,000 as of April 2008.

 

 

 

What are the disorders of the circulatory system?

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Answer & Enrich Your Learning:

  • The circulatory system includes the heart, arteries, veins and capillaries. Also known as the cardiovascular system, this network carries oxygen and nutrients to the body.
  • It also transports waste products to the kidneys, liver and lungs for elimination. Cardiovascular disease is the leading cause of death in the United States, according to the Centers for Disease Control and Prevention (CDC).
  • Circulatory system diseases cover a vast array of different abnormalities and disorders that affect the way the body circulates blood. Circulatory system disorders can lead to decreased perfusion of blood throughout the body, threatening the healthy function of tissue and organs.
  • High blood pressure: Also going by the term hypertension, this is a condition that is defined by the increased force required to pump blood through your arteries.
  • The following points highlight the major disorders of circulatory system: 1. Hypertension 2. Coronary Artery Disease 3. Arteriosclerosis 4. Heart Block 5. Cerebro Vascular Accident 6. Rheumatic Heart Disease 7. Congenital Heart Diseases 8. Oedema 9. Ebstein’s Disease 10. Fibrillation 11. Tachycardia 12. Bradycardia 13. Cardiac arrest 14. Heart failure 15. Heart attack.

 

 

 

How does Liver function?

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Answer & Enrich Your Learning:

  • The liver regulates most chemical levels in the blood and excretes a product called bile. This helps carry away waste products from the liver.
  • All the blood leaving the stomach and intestines passes through the liver. The liver processes this blood and breaks down, balances, and creates the nutrients and also metabolizes drugs into forms that are easier to use for the rest of the body or that are nontoxic.
  • More than 500 vital functions have been identified with the liver.

Some of the more well-known functions include the following:

  1. Production of bile, which helps carry away waste and break down fats in the small intestine during digestion
  2. Production of certain proteins for blood plasma
  3. Production of cholesterol and special proteins to help carry fats through the body
  4. Conversion of excess glucose into glycogen for storage (glycogen can later be converted back to glucose for energy) and to balance and make glucose as needed
  5. Regulation of blood levels of amino acids, which form the building blocks of proteins
  6. Processing of hemoglobin for use of its iron content (the liver stores iron)
  7. Conversion of poisonous ammonia to urea (urea is an end product of protein metabolism and is excreted in the urine)
  8. Clearing the blood of drugs and other poisonous substances
  9. Regulating blood clotting
  10. Resisting infections by making immune factors and removing bacteria from the bloodstream
  11. Clearance of bilirubin, also from red blood cells.

If there is an accumulation of bilirubin, the skin and eyes turn yellow. The hormone insulin is a main regulator of the glucose (sugar) levels in the blood. Insulin is produced by the beta cells in the islets of Langerhans in the pancreas.

 

 

 

Why metal utensils do not work in microwave ovens?

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Answer & Enrich Your Learning:

  • Microwaves are a form of electromagnetic radiation, like radio waves. They are generated by a device called a magnetron, and they pulse back and forth rapidly inside an oven at a carefully calibrated frequency.
  • Microwaves bounce off the oven‘s interior metal walls, pass through paper, glass, and plastic, but they get absorbed by food more specifically, by the food‘s water content.
  • This absorption makes the molecules oscillate back and forth, creating heat and cooking the food from the inside out, the outside in, or uniformly, depending on where the water lies.
  • A metal object placed inside the oven deflects these waves away from the food. It sends them jumping around erratically, possibly damaging the interior of the oven.
  • Sometimes the electromagnetic field within the microwave can get a little mixed up and generate small arcs of electrical discharge.
  • This can be caused by innocuous items like carrots (when grown in mineral rich soil) and hot dogs (when the salt and additives aren’t properly mixed).

 

 

 

What are the potential applications of Graphene?

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Answer & Enrich Your Learning:

  • Potential graphene applications include lightweight, thin, flexible, yet durable display screens, electric/photonics circuits, solar cells, and various medical, chemical and industrial processes enhanced or enabled by the use of new graphene materials.
  • The potential applications of grapheme also include water filtration and purification, renewable energy, sensors, personalised healthcare and medicine, to name a few.
  • Because of its strength, electrical conductivity and elasticity, Graphene been seen as an alternative to lithium-ion batteries since its discovery in 2004.
  • It is a form of carbon that can be used to develop smaller, slimmer batteries but with higher capacity. Graphene is a carbon material that is one atom thick. Its thin composition and high conductivity means it is used in applications ranging from miniaturized electronics to biomedical devices.
  • These properties also enable thinner wire connections; providing extensive benefits for computers, solar panels, batteries, sensors and other devices.
  • Graphene has excellent electronic, mechanical, thermal and optical properties as well. Its uses range from improving battery performance in energy devices, to cheaper solar panels.
  • Graphene produced by exfoliation was one of the most expensive materials on Earth, with a sample the area of a cross section of a human hair costing more than $1,000 as of April 2008.

 

 

 

How Toothpastes help in preventing tooth decay?

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Answer & Enrich Your Learning:

  • Tooth decay starts when pH of the mouth is lower than 5.5 (acidic).
  • Tooth enamel does not dissolve in water, but is corroded when the pH in the mouth is below 5.5.
  • Bacteria present in the mouth produce acids by degradation of sugar and food particles remaining in the mouth after eating food.
  • Using toothpastes, which are generally basic, for cleaning the teeth can neutralize the excess acid and prevent tooth decay.

 

 

 

Define the terms: ‘Photoperiodism’, ‘Chronobiology’, ‘Bioluminescence’ and ‘Scotobiology’.

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Answer & Enrich Your Learning:

Photoperiodism

  • Photoperiodism is the physiological reaction of organisms to the length of day or night. It occurs both in plants and animals.
  • Photoperiodism can also be defined as the developmental responses of plants to the relative lengths of light and dark periods.

Chronobiology

  • Chronobiology is a field of biology that examines periodic phenomena in living organisms and their adaptation to solar- and lunar-related rhythms. These cycles are known as biological rhythms.
  • Chronobiology comes from the ancient Greek, and biology, which pertains to the study, or science, of life.
  • The related terms chronomics and chronome have been used in some cases to describe either the molecular mechanisms involved in chronobiological phenomena or the more quantitative aspects of chronobiology, particularly where comparison of cycles between organisms is required.

Scotobiology

  • Scotobiology describes the study of biology as directly and specifically affected by darkness.
  • This includes work on the effects of darkness on the behavior and metabolism of animals, plants, and microbes.
  • Scotobiology studies the positive responses of biological systems to the presence of darkness, and not merely the negative effects caused by the absence of light.

Bioluminescence

  • Bioluminescence is the production and emission of light by a living organism. It is a form of chemiluminescence.
  • Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some bioluminescent bacteria and terrestrial invertebrates such as fireflies.
  • In some animals, the light is bacteriogenic, produced by symbiotic organisms such as Vibrio bacteria; in others, it is autogenic, produced by the animals themselves.
  • The principal chemical reaction in bioluminescence involves some light-emitting molecule and an enzyme, generally called the luciferin and the luciferase.
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70 Days Prelims Flash Cards 2019
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