• This is very brief revision note for S&T portion of CSAT GS Paper I.
  • I’m running out of time so the content is not properly classified and sentences are incomplete.
  • Message to those feeling extremely stressed for 20th May :  Heroes may not be braver than anyone else. They’re just brave five minutes longer.
  1. Carburettor
  2. Biodiversity
  3. Muscle
  4. Artic vs Antarctic
  5. Radioactive food
  6. Bats n bees
  7. Evaporation
  8. Hydrogen fuel
  9. Mobile switched off in airplane
  10. Probiotics, prebiotics
  11. E.Coli
  12. Diesel engine
  13. Dish TV
  14. Euthanasia
  15. Burning flame


  • Carburettor gives air and petrol mixture and fuel injection pump gives a spray form of diesel using a nozzle to the engine input side.
  • When we press the accelerator, a small plate like opening allows the carburettor to draw more air from atmosphere, and also this action draws more fuel(petrol) from the fuel tank
  • Venturi action means a fluid or gas flowing through a constricted section of a tube undergoes a decrease in pressure, so due to pressure difference fuel comes from the tank
  • When we use the choke option in the vehicle during starting problem, it is qualitatively changing the ratio of air and fuel for easy starting during winter or cold condition of the engine.


  • Cactus is getting attention in every continent as vital crop for increasing plant cover, carbon sequestration, livestock feeding, conserving wildlife, medicinal and cosmetic uses
  • Goa-based National Centre for Antarctic and Ocean Research (NCAOR).


  • What enables the ants to carry heavier objects is their relatively smaller body size
  • Larger animals like humans need to put most of the muscles in use to carry their own mass. In other words, larger animals have to carry their own weight, besides the heavier objects; so they are able to carry only slightly heavier objects.
  • Thus, ants could use more muscles to carry bigger loads than their own mass, which not only applies to ants, but also holds good for most of the insects.
  • ^ this is because of the square – cube law
  • Ants and termites perform the same ecosystem service functions in dryland agriculture that earthworms perform in cooler and wetter areas and have a significant positive impact on crop yields in dryland agriculture

Artic vs Antarctic

  • Two regions, the Arctic and the Antarctica, are located around the north and the south poles of the earth, respectively.
  • Rotation at the (Antarctic) south pole is opposite to that at (Arctic) north pole.  This is manifest in the nature of wind circulation and in the water whirlpools. Also, being in the two opposite hemispheres, there exists a complementarity in the seasonal changes.
  • Winter period at the Arctic happens to be the summer in the Antarctica and vice versa.
  • Arctic is an ocean with frozen ice cover. It is surrounded and partly contributed by the edges of land masses, while the Antarctica is an ice covered land mass (continent) surrounded by oceans.  This leads to differences in the temperature patterns in the two regions.
  • Much of arctic zone is surrounded by relatively warmer ocean water with minimum temperature above -2 degree Celsius. In the Antarctica the interior regions do not benefit from the moderating influence of the ocean waters.

Radioactive food

  • Brazil nut is probably the most radioactive food. Scientists have measured 700Bq of radium per kg of Brazil nut.
  • Roots of the Brazil nut tree pass through acres of land; They have a tendency to concentrate barium; along with barium, the roots collect radium as well. Radium appears in the nuts. Many vegetables like brinjal, carrot etc.  Also contain the radioactive isotope

Bats n bees

  • Fruit bats use biosonar to =see’ their surroundings
  • Wet bat needs more energy to fly because damp fur provides less protection than when dry. Wet fur also affects the bat’s aerodynamics, which in turn also costs energy
  • Raindrops affected the bat’s echo-finding capability.
  • India ranks second to China in the global map in vegetable production
  • Average beehive produces as much as 45-50 kg of bee dung a year, neatly deposited around the beehive as high nitrogenous manure. ?When it rains, this pollen dung gets washed into the soil, breaks down and provides an excellent natural fertilizer.
  • Hence, to a farmer rearing bees in a field to pollinate the crop, he gets an additional bonus in the form of manure
  • Bionic eye =A microchip packed with 1,500 light sensors is implanted to the back of the eye.
  • Sensors convert light to electrical signals, which stimulate nerves in the retina to pass down signals to optic nerve which would gap into the brain to form an image.
  • Blue Brain Project =Blue here symbolizing supercomputers. Project aims to build brain models.


  • Evaporation is the physical process by which molecules of a liquid leave the liquid surface into the vapour phase. This takes place at all temperatures
  • Evaporation rate is proportional to the area of the exposed surface.  Hence, in large water bodies like ponds, lakes and oceans, the amount of water transforming into vapour phase is considerably large even at ambient temperatures,
  • This water vapour which saturates the air just above the water body, gets swept
  • Away by wind which replaces the saturated air by fresh air containing less of water vapour. And, water vapour is lighter than the air and so, the water vapour floats up.
  • This leads to further evaporation of water from the water body.
  • Accumulation of water vapour forms the cloud mass.

Hydrogen fuel

  • Hydrogen makes a great fuel because of it can easily be converted to electricity in a fuel cell and because it is carbon free.
  • Downside of hydrogen is that, because it is a gas, it can only be stored in high Pressure or cryogenic tanks.
  • Biofortification = effort to increase the amounts of available micronutrients in staple crops such as cassava
  • NASA’s Cassini spacecraft – studying Saturn planet.

Mobile switched off in airplane

  • At high altitudes, the pilots have to largely depend on the avionics and computer-assisted coded signal communications.  All the wireless signal trafficking is accomplished by modulated radio and microwave transmissions which type the cell phones also owe their functioning to.
  • If there are any mobile phones on board in the cabin of the flight in = on’ mode during takeoff, flight and landing, the microwave transmission between the mobile phone towers and the mobile phones might interfere with the communications the flights are busily engaged in (between the cockpit and the control towers).
  • That’s why we are asked to switch off our mobile or keep in flight mode when we are travelling in a flight.
  • Anyway, the cell phones cannot serve as phones on board the flights because the cell phone towers on the ground cannot connect themselves to the phones at such high altitudes and such high flight speeds.
  • Nanopatch, having 20,000 micro projections per square centimetre, is designed to directly place vaccine into the human skin, which is rich in immune cells. And unlike the needle and syringe, which places vaccine into the muscle — which has very few immune cells
  • In 2003, China became the third country to send an astronaut into space on its own, four decades after the United States and Russia.
  • China plans to send a drilling machine on board its fifth lunar probe, Chang’e-5, in 2017 to drill the moon surface deep and bring back rock samples to the earth
  • Primary function of the clutch is to disconnect the engine from the remaining parts of the power transmission system at the will of the driver by the use of a suitable lever thereby permitting the engine to run without driving the vehicl
  • We start the vehicle from a stand-still position, the force that the engine has to overcome to get the vehicle moving is the friction between the tyres and the road surface and it is proportional to the weight of the vehicle and the contact surface area of the tyres.
  • To get the vehicle moving, the driver engages the clutch and then shifts to the primary gear whose gear ratio is such that when engaged, the final drive moves at a considerably lesser speed when compared to the engine.
  • Lovejoy =recently discovered Comet.
  • Indian poultry breed, called Kadaknath is native to Jhabua district of Madhya Pradesh. Breed is famous for its black meat known for its quality, texture and flavour. An attempt was therefore made for conservation and promotion of this high value Indian poultry race under National Agriculture Innovation Project (NAIP)
  • Computed tomography (CT) as the best way to detect cocaine in the body of a =mule.’

Probiotics, prebiotics

  • We call these organisms, and/or their molecules, as probiotics and prebiotics.  The microbes are called probiotics, and the indigestible (to us) material that they feed on is the prebiotic.  Prebiotics are nonliving material such as starch or husk, while probiotics are live organisms. (And biotic means relating to, produced by, or caused by living organisms).
  • Without them, we cannot make some essential nutrients such as vitamin K, or metabolize bile acids, cholesterol and some short chain fatty acids. They also help us in fighting pathogenic bacteria and viruses — a case of internal colonizers acting as defending soldiers against alien invaders.


  • Escherichia coli, a bacterium that is found in the gut, spreads easily through faecal contamination of food and water. It is a common cause of urinary infections, and can also produce pneumonia and life-threatening bloodstream infections in hospitalised patients
  • Disease-causing strains of E. Coli, K. Pneumoniae and other Gram-negative bacteria have emerged with special genes that produce enzymes and make the bacteria immune to the effects of a wide range of antibiotics. (related: TB resistance and DOTs)
  • NASA’s Dawn spacecraft To study the asteroid Vesta.

Diesel engine

  • Why do diesel internal combustion engines require no spark plug to ignite the fuel unlike petrol engines?
  • Spark plugs are used in the petrol engines to ignite the air fuel mixture whereas in diesel engines the presence of spark plugs is not necessary.
  • Technically petrol engines are Called as spark ignition engines ( SI ) and diesel engines are called as compression ignition engines (CI )
  • In SI engines air and fuel (petrol) get mixed in the carburettor and then it is supplied to the engine through inlet manifold, then the air fuel mixture is compressed inside the cylinder.
  • At the end of compression the spark is ignited and then combustion takes place
  • The air from the atmosphere is sucked into the cylinder of the engine and then the air is compressed to high pressure which eventually leads to the increase of temperature, so when the diesel is supplied at end of compression stroke, the temperature developed is more enough to ignite the diesel, this makes the fuel to burn and then expansion of gases takes place from where the power stroke is obtained.
  • In petrol engines spark plugs will be present but in the case of diesel engines fuel pump will be present.

Dish TV

  • During rains, the TV programs telecast by dish TV providers are disrupted or blocked. Why?
  • Loss or weakening of satellite signal during bad weather is called =rain fade’ or =rain attenuation.’
  • Rain fade occurs due to the presence of moisture in the air between the transmitting satellite and the receiver site.  Moisture interferes with the satellite signal. The raindrops weaken the transmission by absorbing and scattering the electromagnetic signals.
  • Earlier satellite television was broadcast in C-band – radio in the 3.4-gigahertz (ghz) to 7-ghz frequency range. Currently, digital satellite TV is transmitted in the Ku frequency range (10 ghz to 14 ghz )
  • Longer wavelengths of C-band are less susceptible to rain attenuation than the shorter Ku and Ka wavelengths.
  • Destructive tsunami generated by the March 2011 Japan earthquake was a =merging tsunami’ that doubled in intensity over rugged ocean ridges, amplifying its destructive power before reaching shore.


  • Assisted dying or assisted suicide is not illegal in Switzerland
  • Other countries excluding Switzerland have legalised assisted dying — Belgium, Luxembourg and the Netherlands.
  • Epigenetic memory enables plants to remember the length of the cold winter period in order to time flowering so that pollination, seed dispersal and germination can all happen at the appropriate time.
  • Radiation typically kills many bone marrow cells, which can lead to a compromised immune system in patients, leaving them vulnerable to infections and other health problems.
  • Hibernating animals provide good example for utilizing fat reserve as fuel.  For instance, polar bears go on hibernation for about seven months and, during this entire period, the energy is derived from the degradation of stored fat.
  • Fats can also support the body’s energy needs for long periods of food deprivation.

Burning flame

  • All fuels get oxidised by burning; but, all oxidation reactions do not constitute burning.
  • Flame is quite an accidental feature.  Thus, iron burning in oxygen gives no perceptible flame. The intense light is due to the incandescent solid. On the other hand, phosphorus, sulphur, wax, etc., burn with a flame because these solids are volatilized at the temperature of combustion.
  • The colour of the flame depends upon the material undergoing the reaction and the temperature.