Flash Card

LAKSHYA-75 [Day-5] Static Flash Cards for IAS Prelims 2020

Ultrasound; Methods of irrigation; Structure of a flame; Biosphere reserves; Comparison of plant and animal cell; Electroplating; Thomson’s Model of an Atom; Cell organelles; Complex Permanent Tissue; Whittaker’s classification of living organisms;
By IASToppers
March 10, 2020



SONAR uses which waves in the Electromagnetic Spectrum?

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SONAR uses Ultrasound waves to measure the distance, direction and speed of underwater objects.

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  • Ultrasounds are high frequency waves.
  • Ultrasounds are able to travel along well-defined paths even in the presence of obstacles. Ultrasounds are used extensively in industries and for medical purposes.

Applications of Ultrasound:

  1. Clean parts:
  • Ultrasound is used to clean parts located in hard-to-reach places, for example, spiral tube, odd shaped parts, electronic components etc.
  • Objects to be cleaned are placed in a cleaning solution and ultrasonic waves are sent into the solution.
  • Due to the high frequency, the particles of dust, grease and dirt get detached and drop out.
  1. Detect cracks and flaws:
  • Ultrasounds can be used to detect cracks and flaws in metal blocks.
  • Metallic components are generally used in construction of big structures like buildings, bridges, machines and also scientific equipment.
  • The cracks or holes inside the metal blocks, which are invisible from outside reduces the strength of the structure.
  • Ultrasonic waves are allowed to pass through the metal block and detectors are used to detect the transmitted waves.
  • If there is even a small defect, the ultrasound gets reflected back indicating the presence of the flaw or defect.
  • Ordinary sound of longer wavelengths cannot be used for such purpose as it will bend around the corners of the defective location and enter the detector.
  1. Echocardiography:
  • Ultrasonic waves are made to reflect from various parts of the heart and form the image of the heart. This technique is called ‘echocardiography’.
  • Ultrasound scanner is an instrument which uses ultrasonic waves for getting images of internal organs of the human body.
  • A doctor may image the patient’s organs such as the liver, gall bladder, uterus, kidney, etc.
  1. Ultrasonography:
  • It helps the doctor to detect abnormalities, such as stones in the gall bladder and kidney or tumors in different organs.
  • In this technique the ultrasonic waves travel through the tissues of the body and get reflected from a region where there is a change of tissue density.
  • These waves are then converted into electrical signals that are used to generate images of the organ. These images are then displayed on a monitor or printed on a film. This technique is called ‘ultrasonography’.
  • Ultrasonography is also used for examination of the foetus during pregnancy to detect congenial defects and growth abnormalities.
  • Ultrasound may be employed to break small ‘stones’ formed in the kidneys into fine grains.
  1. SONAR:
  • The acronym SONAR stands for Sound Navigation and Ranging.
  • Sonar is a device that uses ultrasonic waves to measure the distance, direction and speed of underwater objects.

How does the sonar work?

  • Sonar consists of a transmitter and a detector and is installed in a boat or a ship.
  • The transmitter produces and transmits ultrasonic waves.
  • These waves travel through water and after striking the object on the seabed, get reflected back and are sensed by the detector.
  • The detector converts the ultrasonic waves into electrical signals which are appropriately interpreted.
  • The distance of the object that reflected the sound wave can be calculated by knowing the speed of sound in water and the time interval between transmission and reception of the ultrasound.
  • The sonar technique is used to determine the depth of the sea and to locate underwater hills, valleys, submarine, icebergs, sunken ship etc.



The organisms which use appendages or hair-like cilia for moving around are called?

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Protista use appendages, such as hair-like cilia or whip-like flagella for moving around.

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Whittaker’s classification of living organisms:

Whittaker proposed an elaborate five kingdom classification – Monera, Protista, Fungi, Plantae and Animalia. The main criteria of the five kingdom classification were cell structure, body organisation, mode of nutrition and reproduction, and phylogenetic relationships.


  • These organisms do not have a defined nucleus or organelles, nor do any of them show multi-cellular body designs.
  • On the other hand, they show diversity based on many other characteristics. Some of them have cell walls while some do not.
  • Of course, having or not having a cell wall has very different effects on body design here from having or not having a cell wall in multicellular organisms.
  • The mode of nutrition of organisms in this group can be either by synthesizing their own food (autotrophic) or getting it from the environment (heterotrophic).
  • Examples: Bacteria, blue-green algae or cyanobacteria, and mycoplasma.


  • This group includes many kinds of unicellular eukaryotic organisms.
  • Some of these organisms use appendages, such as hair-like cilia or whip-like flagella for moving around.
  • Their mode of nutrition can be autotrophic or heterotrophic.
  • Examples: Unicellular algae, diatoms and protozoans.


  • These are heterotrophic eukaryotic organisms.
  • Some of them use decaying organic material as food and are therefore called saprotrophs.
  • Others require a living protoplasm of a host organism for food.
  • They are called
  • Many of them have the capacity to become multicellular organisms at certain stages in their lives.
  • They have cell walls made of a tough complex sugar called
  • Examples: Yeasts, molds and mushrooms.
  • Some fungal species live in permanent mutually dependent relationships with blue-green algae (or cyanobacteria).
  • Such relationships are called
  • These symbiotic life forms are called
  • We have all seen lichens as the slow-growing large colored patches on the bark of trees.


  • These are multicellular eukaryotes with cell walls.
  • They are autotrophs and use chlorophyll for photosynthesis.
  • Thus, all plants are included in this group.


  • These include all organisms which are multicellular eukaryotes without cell walls.
  • They are



Which complex Permanent tissue transports food from leaves to other parts of the plant?

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Phloem transports food from leaves to other parts of the plant.

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Complex Permanent Tissue:

  • Complex tissues are made of more than one type of cells.
  • All these cells coordinate to perform a common function.
  • Xylem and phloem are examples of such complex tissues.
  • They are both conducting tissues and constitute a vascular bundle.
  • Vascular tissue is a distinctive feature of the complex plants, one that has made possible their survival in the terrestrial environment.


  • Xylem consists of tracheids, vessels, xylem parenchyma and xylem fibers.
  • Tracheids and vessels have thick walls, and many are dead cells when mature. Tracheids and vessels are tubular structures.
  • This allows them to transport water and minerals vertically.
  • The parenchyma stores food.
  • Xylem fibers are mainly supportive in function.


  • Phloem is made up of five types of cells: sieve cells, sieve tubes, companion cells, phloem fibers and the phloem parenchyma.
  • Sieve tubes are tubular cells with perforated walls.
  • Phloem transports food from leaves to other parts of the plant.
  • Except phloem fibers, other phloem cells are living cells.



Which cell organelle serves as the channel for the transport of proteins between various regions of the cytoplasm?

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Endoplasmic reticulum serves as the channel for the transport of proteins between various regions of the cytoplasm.

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Cell organelles:

An organelle is a membrane bound structure found within a cell with distinctive functions. The important cell organelles are:

Endoplasmic Reticulum:

  • The endoplasmic reticulum (ER) is a large network of membrane-bound tubes and sheets.
  • It looks like long tubules or round or oblong bags (vesicles).
  • The ER membrane is similar in structure to the plasma membrane.
  • There are two types of ER– rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER).

Rough endoplasmic reticulum:

  • RER looks rough under a microscope because it has particles called ribosomes attached to its surface.
  • The ribosomes are the sites of protein manufacture.
  • The manufactured proteins are then sent to various places in the cell depending on need, using the ER.

Smooth endoplasmic reticulum:

  • The SER helps in the manufacture of fat molecules, or lipids, important for cell function.
  • Some of these proteins and lipids help in building the cell membrane.
  • This process is known as membrane biogenesis.
  • Some other proteins and lipids function as enzymes and hormones.
  • Although the ER varies greatly in appearance in different cells, it always forms a network system.
  • Thus, one function of the ER is to serve as channels for the transport of materials (especially proteins) between various regions of the cytoplasm or between the cytoplasm and the nucleus.
  • The ER also functions as a cytoplasmic framework providing a surface or some of the biochemical activities of the cell.
  • In the liver cells of the group of animals called vertebrates, SER plays a crucial role in detoxifying many poisons and drugs.

Golgi Apparatus:

  • The Golgi apparatus, first described by Camillo Golgi, consists of a system of membrane-bound vesicles (flattened sacs) arranged approximately parallel to each other in stacks called cisterns.
  • These membranes often have connections with the membranes of ER and therefore constitute another portion of a complex cellular membrane system.
  • The material synthesized near the ER is packaged and dispatched to various targets inside and outside the cell through the Golgi apparatus.
  • Its functions include the storage, modification and packaging of products in vesicles.
  • In some cases, complex sugars may be made from simple sugars in the Golgi apparatus.
  • The Golgi apparatus is also involved in the formation of lysosomes.



Christmas pudding or watermelon model of atom was suggested by?

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  1. J. Thomson suggested Christmas pudding or watermelon model of an atom.

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Thomson’s Model of an Atom:

  • Thomson proposed the model of an atom to be similar to that of a Christmas pudding.
  • The electrons, in a sphere of positive charge, were like dry fruits in a spherical Christmas pudding.
  • We can also think of a watermelon, the positive charge in the atom is spread all over like the red edible part of the watermelon, while the electrons are studded in the positively charged sphere, like the seeds in the watermelon.

Thomson proposed that:
(i) An atom consists of a positively charged sphere and the electrons are embedded in it.

(ii) The negative and positive charges are equal in magnitude. So, the atom as a whole is electrically neutral.

Although Thomson’s model explained that atoms are electrically neutral, but the model could not be verified experimentally.



What is electroplating?

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The process of depositing a layer of any desired metal on another material, by means of electricity is called electroplating.

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  • The process of depositing a layer of any desired metal on another material, by means of electricity, is called electroplating.
  • The process involves passing electric current through a solution called an electrolyte.
  • Two terminals called electrodes are dipped into the electrolyte and connected into a circuit with a battery or other power supply.
  • The electrodes and electrolyte are carefully chosen elements.
  • When the electricity flows through the circuit, the electrolyte splits up and some of the metal atoms it contains are deposited in a thin layer on top of one of the electrodes and it becomes electroplated.
  • The process can be used to electroplate all kinds of metals including gold, silver, tin, zinc, copper, cadmium, chromium, nickel, platinum, and lead.



Plastids are absent in Animal cells. True OR False.

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Comparison of plant and animal cell:



Plant Cell

Animal Cell


Cell wall




Cell shape


Round or Irregular



Large central vacuole 

One or more small vacuoles











Usually absent



Plasma Membrane

Cell wall and cell membrane

Only cell membrane







How many biosphere reserves are there in India?

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India has 18 biosphere reserves presently (March 2020).

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Biosphere reserves:

  • The Indian government has established 18 biosphere reserves in India which protect larger areas of natural habitat than a typical national park or animal sanctuary, and often include one or more national parks or preserves, along with buffer zones that are open to some economic uses.
  • Protection is granted not only to the flora and fauna of the protected region, but also to the human communities who inhabit these regions, and their ways of life.

Biosphere reserves in India:

There are 18 biosphere reserves in India:

  1. Cold Desert, Himachal Pradesh
  2. Nanda Devi, Uttarakhand
  3. Khangchendzonga, Sikkim
  4. Dehang-Debang, Arunachal Pradesh
  5. Manas, Assam
  6. Dibru-Saikhowa, Assam
  7. Nokrek, Meghalaya
  8. Panna, Madhya Pradesh
  9. Pachmarhi, Madhya Pradesh
  10. Achanakmar-Amarkantak, Madhya Pradesh-Chhattisgarh
  11. Kachchh, Gujarat
  12. Similipal, Odisha
  13. Sundarban, West Bengal
  14. Seshachalam, Andhra Pradesh
  15. Agasthyamalai, Karnataka-Tamil Nadu-Kerala
  16. Nilgiri, Tamil Nadu-Kerala (First to be Included)
  17. Gulf of Mannar, Tamil Nadu
  18. Great Nicobar, Andaman & Nicobar Island

UNESCO World Network of Biosphere Reserves:

  • The UNESCO World Network of Biosphere Reserves (WNBR) covers internationally designated protected areas, each known as biosphere reserves.
  • It works to foster the harmonious integration of people and nature for sustainable development through participatory dialogue, knowledge sharing, poverty reduction, human well-being improvements, respect for cultural values and by improving society’s ability to cope with climate change.
  • It promotes North-South and South-South collaboration and represents a unique tool for international cooperation through the exchange of experiences and know-how, capacity-building and the promotion of best practices.
  • As of 2019 total membership had reached 686 biosphere reserves in 122 countries (including 20 transboundary sites) occurring in all regions of the world.



The hottest part of a flame is: a) Outermost part OR b) Innermost part?

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The Outermost part of a flame is the hottest.

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Structure of a flame:

A flame has three distinct colors:

  1. Inner Part:
  • This is the innermost part of the flame.
  • The part is closest to the wick.
  • It is assumed to be the hottest part of the flame. However, it is the least hot.
  • This is the black part of the flames that contains unburnt particles of the carbon from the wick i.e. unburnt fuel.
  1. Middle Part:
  • This is the biggest part of the flame.
  • The colors in this are varying shades of yellow and orange.
  • This is the luminous flame because it emits light.
  • This part gets a limited supply of oxygen and is not extremely hot.
  • Incomplete combustion takes place here, so it burns orange and is luminous.
  1. Outer Part:
  • It is the hottest part of the flame.
  • It has an unlimited supply of oxygen. So complete combustion takes place here. Hence it is the hottest part of the flame.
  • The part of the flame burns with a blue colour.
  • It is the non-luminous, i.e. does not emit light.



Dhekli and Rahat are the soil management techniques followed primarily in north-eastern parts of India. True OR False.

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Correct statement:

  • Dhekli and Rahat are the traditional methods of irrigation systems.

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Methods of irrigation:

Traditional Methods of Irrigation:

  • The water available in wells, lakes and canals is lifted up by different methods in different regions, for taking it to the fields.
  • Cattle or human labour is used in these methods. So these methods are cheaper, but less efficient.
  • The various traditional ways are:

(i) Moat (pulley-system)

(ii) Chain pump

(iii) Dhekli, and

(iv) Rahat (Lever system)

  • Pumps are commonly used for lifting water. Diesel, biogas, electricity and solar energy is used to run these pumps.

Modern Methods of Irrigation:

Sprinkler System:

  • This system is more useful on the uneven land where sufficient water is not available.
  • The perpendicular pipes, having rotating nozzles on top, are joined to the main pipeline at regular intervals.
  • When water is allowed to flow through the main pipe under pressure with the help of a pump, it escapes from the rotating nozzles.
  • It gets sprinkled on the crop as if it is raining.
  • Sprinkler is very useful for lawns, coffee plantation and several other crops.

Drip system:

  • In this system, the water falls drop by drop directly near the roots. So it is called drip system.
  • It is the best technique for watering fruit plants, gardens and trees.
  • Water is not wasted at all. It is a boon in regions where availability of water is poor.
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