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Type: Prelims Only

  • Innovations in Biotechnology and Medical Sciences

    TR1 Cells: The Hidden Warriors in Malaria Immunity

    Prelims Only | Science Tech | Mains Paper 3: Awareness in various sc and tech fields

    Why in the News?

    Scientists at Stanford University discovered that TR1 cells play a dominant role in fighting malaria reinfections.

    Understanding the Body’s Immune Response:

    • What is the Immune System? It’s the body’s defence system that protects us from infections like malaria.
    • First Defence: The skin and body surfaces block germs from entering.
    • Innate Immunity: If germs get in, the innate immune system reacts fast, like an emergency response team.
    • Adaptive Immunity: Then, the adaptive immune system kicks in, targeting germs specifically and remembering them for future protection.
    • B-Cells and T-Cells:
      • B-cells make antibodies to fight germs.
      • T-cells attack infected cells and guide other immune cells.
    • Helper T-Cells: A type called CD4+ T-cells helps organise the defence. Earlier, scientists thought TH1 cells were key in malaria, but a new study shows TR1 cells are more important, especially in repeat infections.

    What are TR1 Cells?

    • Role of TR1 Cells: These are special T-cells that help control the immune system and prevent overreaction.
    • Major Response in Malaria: Though small in number, during malaria, TR1 cells become the main helper cells.
    • Study in Uganda: In young children with repeated malaria, TR1 cells grew in number and improved the body’s ability to fight malaria without severe illness.
    • Memory and Immunity: TR1 cells remember the malaria parasite and return stronger with each infection.
    • Types of TR1 Cells:
      • Naïve TR1 – not yet active.
      • Effector TR1 – fighting infection.
      • Memory TR1 – remembering past infections.
    • Epigenetic Role: TR1 cells may respond by switching genes on or off, not by changing the genes themselves.

    Key Findings of the Study:

    • Research Team: Scientists from Stanford University studied people in Uganda over many months and years.
    • Tracking Infections: They followed individuals through multiple malaria infections to see how immune cells behaved.
    • Gene Scanning: A special technique was used to read the genes of each immune cell — like scanning a barcode.
    • Findings: TR1 cells were accurate, long-lasting, and clearly connected to malaria (not other infections).
    • Why it matters: This discovery can help in making better malaria vaccines, boosting long-term protection, and even improving treatments for other serious diseases.
    [UPSC 2025] With reference to monoclonal antibodies, consider the following:

    I. They are man-made proteins. II. They stimulate the patient’s immune system to fight the specific disease. III. They are produced using animal cells only.

    Which of the statements given above are correct?

    Options: (a) I and II only (b) II and III only (c) I and III only (d) All the three *

     

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  • Minimum Support Prices for Agricultural Produce

    Cabinet approves hike in MSP for Kharif Crops

    Prelims Only | Agriculture | Mains Paper 3: Issues Related To Farm Subsidies & Msp

    Why in the News?

    The Cabinet Committee on Economic Affairs chaired by Prime Minister has approved the increase in the Minimum Support Price (MSP) for 14 kharif crops for 2025-26.

    What is the Minimum Support Price (MSP)?

    • MSP in India originated in response to food shortages in the 1960s, notably during the Bihar famine of 1966–1967.
    • Agricultural Price Commission (APC) was established in 1965 to implement price policies like procurement at pre-decided prices and MSP.
    • Over time, the APC evolved into the Commission for Agricultural Costs and Prices (CACP) in 1985, with broader terms of reference.
    • Announcement: The government bases its announcement on the recommendations given by the Commission for Agricultural Costs & Prices (CACP).

    Steps involved in Fixing MSPs:

    • CACP sends its recommendations to the Government of India.
    • The reports are shared with state governments and concerned central ministries for comments.
    • After reviewing all inputs, the Cabinet Committee on Economic Affairs (CCEA) takes the final decision on MSPs.
    • Once approved, CACP publishes all its reports online, ensuring transparency and explaining the rationale behind its recommendations.

    How is MSP fixed?

    • Formulae for Calculation:
      • A2: Costs incurred by the farmer in production of a particular crop. It includes several inputs such as expenditure on seeds, fertilisers, pesticides, leased-in land, hired labour, machinery and fuel
      • A2+FL: Costs incurred by the farmer and the value of family labour
      • C2: A comprehensive cost, which is A2+FL cost plus imputed rental value of owned land plus interest on fixed capital, rent paid for leased-in land
    • National Commission of Farmers also known as the Swaminathan Commission (2004) recommended that the MSP should at least be 50 per cent more than the weighted average Cost of Production (CoP), which it refers to as the C2 cost.
    • The government maintains that the MSP was fixed at a level of at least 1.5 times of the all-India weighted average CoP, but it calculates this cost as 1.5 times of A2+FL.
    • Crops covered are: CACP currently recommends MSPs for 23 key crops:
      • 7 Cereals: Paddy, Wheat, Maize, Sorghum (Jowar), Pearl Millet (Bajra), Barley, and Ragi
      • 5 Pulses: Gram (Chana), Tur (Arhar), Moong, Urad, and Lentil (Masur)
      • 7 Oilseeds: Groundnut, Rapeseed-Mustard, Soybean, Sesame, Sunflower, Safflower, and Nigerseed
      • 4 Commercial Crops: Copra, Cotton, Raw Jute and Sugarcane (Fair and Remunerative Price (FRP) is announced by CACP.)
    [UPSC 2020] Consider the following statements:

    1. In the case of all cereals, pulses and oil-seeds, the procurement at Minimum Support Price (MSP) is unlimited in any State/UT of India.

    2. In the case of cereals and pulses, the MSP is fixed in any State/UT at a level to which the market price will never rise.

    Which of the statements given above is/are correct?

    Options: (a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2*

     

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  • Judicial Appointments Conundrum Post-NJAC Verdict

    Supreme Court Collegium recommends transfer of HC CJs

    Prelims Only | Polity | Mains Paper 2: Executive & Judiciary

    Why in the News?

    The Supreme Court Collegium has recommended the transfer of 4 Chief Justices from the High Courts of Madras, Rajasthan, Tripura, and Jharkhand.

    About the Collegium System:

    • Definition: It is used in India for the appointment and transfer of judges to the Supreme Court and High Courts.
    • Non-Constitutional Origin: It is not mentioned in the Constitution or any law passed by Parliament. It developed through Supreme Court judgments to protect judicial independence.
    • Judicial Primacy: The system ensures that senior judges, not the government, have the main say in judicial appointments.
    • Evolution: It arose in response to executive interference during the 1970s, when the government tried to influence and supersede senior judges:
    • First Judges Case (1981) – S.P. Gupta v. Union of India:
      • Held that the Chief Justice’s opinion was only consultative.
      • Gave the executive primary control over appointments and transfers.
    • Second Judges Case (1993) – Advocates-on-Record Association v. Union of India:
      • Overruled the First Judges Case.
      • Declared that “consultation” with the CJI means “concurrence”, making the CJI’s view binding.
      • Introduced the Collegium system, involving the CJI and two senior-most judges.
      • Affirmed that judicial independence requires judicial primacy in appointments.
    • Third Judges Case (1998) – Re: Presidential Reference:
      • Expanded the Collegium to include the CJI and four senior-most Supreme Court judges.
      • Emphasised institutional decision-making, not personal preferences of individual judges.

    How does the Collegium System works?

    • For Supreme Court Judges:
      • The Collegium includes the CJI and four senior-most SC judges.
      • It recommends names for appointments to the SC and appointments/transfers of High Court judges and Chief Justices.
      • The Law Ministry processes these names and sends them to the Prime Minister, who advises the President for final approval.
    • For Appointing the Chief Justice of India:
      • The sitting CJI recommends the senior-most SC judge.
      • This practice has been followed since the 1970s supersession controversy.
    • For High Court Judges:
      • Recommendations start from the Chief Justice of the High Court, who consults two senior colleagues.
      • The proposal goes to the state government, then to the Supreme Court Collegium (CJI and two senior-most SC judges), and finally to the President.
    • For Transfers of Judges:
      • Article 222 of the Constitution allows transfer of High Court judges.
      • The Collegium recommends transfers, often for administrative needs or public interest.
      • Consent is not needed, but the CJI must consult the Chief Justice of the concerned High Court and other senior judges.
      • No High Court can have an Acting Chief Justice for more than a month, so transfers and new appointments are usually done together.

    Tap to know more about the Appointment and Removal of HC Judges.

    [UPSC 2012] What is the provision to safeguard the autonomy of the Supreme Court of India?

    1. While appointing the Supreme Court Judges, the President of India has to consult the Chief Justice of India. 2. The Supreme Court Judges can be removed by the Chief Justice of India only. 3. The salaries of the Judges are charged on the Consolidated Fund of India to which the legislature does not have to vote. 4. All appointments of officers and staff of the Supreme Court of India are made by the Government only after consulting the Chief Justice of India. Which of the statements given above is/are correct?

    Options: (a) 1 and 3 only * (b) 3 and 4 only (c) 4 only (d) 1, 2, 3 and 4

     

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  • Monsoon Updates

    Bow Echo Storms

    Prelims Only | Geography | Mains Paper 1: Salient Features Of World’S Physical Geography

    Why in the News?

    New Delhi recently faced a severe thunderstorm with winds up to 100 kmph, forming a bow echo — a crescent-shaped pattern seen on weather radar.

    About Bow Echo:

    • What is it: A bow echo is a storm pattern on radar that looks like a curved bow, similar to an archer’s bow.
    • Storm Type: It forms inside a mesoscale convective system (MCS) — a large group of organised thunderstorms.
    • Origin of Term: The term was first used by Ted Fujita, who also created the Fujita scale for tornadoes.
    • How It Forms:
      • Heavy rain causes cool air to sink and spread out near the ground.
      • This cool air forms a gust front, which pushes warm, moist air upward, creating new storms.
      • A rear inflow jet — strong mid-level winds — pushes the storm forward, bending it into a bow shape.
      • Bookend vortices may form at both ends of the bow, and the northern end can sometimes generate tornadoes.

    Size, Impact, and Dangers:

    • Size and Duration: Bow echoes usually span 20 to 200 km and last 3 to 6 hours.
    • Wind Strength: They often produce straight-line winds over 100 km/h, like those seen in Delhi’s recent storm.
    • Derechos: In severe cases, bow echoes can grow into derechos, which are long-lasting and widespread windstorms.
    • Impacts:
      • Damaging Winds: Knock down trees, power lines, and damage buildings.
      • Brief Tornadoes: May form at the storm’s edges, especially at the northern end.
      • Microbursts and Downbursts: Intense short-lived wind blasts within the storm that cause local destruction.
    [UPSC 2013] During a thunderstorm, the thunder in the skies is produced by the-

    1. Meeting of cumulonimbus clouds in the sky 2. Lightning that separates the nimbus clouds 3. Violent upward movement of air and water particles.

    Select the correct answer using the codes given below.

    Options: (a) 1 only (b) 2 and 3 (c) 1 and 3 (d) None of the above produces the thunder*

     

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  • Monsoon Updates

    What is Madden-Julian Oscillation (MJO)?

    Prelims Only | Geography | Mains Paper 1: Geographical Features & Their Location

    Why in the News?

    Mumbai got heavy monsoon rains two weeks early because of a strong Madden-Julian Oscillation (MJO) — a weather pattern that boosts rainfall in the region.

    About the Madden-Julian Oscillation (MJO):

    • Definition: The MJO is a moving weather system of clouds, wind, rain, and pressure that travels eastward around the tropics.
    • Cycle Time: It takes 30 to 60 days to complete a full loop around the globe.
    • Discovery: It was discovered in the 1970s by Roland Madden and Paul Julian.
    • Two Phases:
      1. The enhanced convective phase brings heavy rain, storms, and clouds.
      2. The suppressed convective phase brings dry, clear weather.
    • Global Pattern: These phases move together — when one area gets rain, another gets dry weather.
    • MJO vs ENSO: Unlike El Niño, which lasts for months, the MJO changes every few weeks and affects short-term weather patterns.
    • Wider Impact: It influences monsoons, cyclones, jet streams, and weather in both tropical and non-tropical regions.
    • Phases: Scientists divide its movement into 8 phases, each showing where rain or dry weather will occur.

    MJO and the Early Monsoon of 2025:

    • Early Monsoon Trigger: The early arrival of the monsoon in May 2025 was largely due to a very active MJO.
    • IMD Observation: The India Meteorological Department noted that the MJO was in Phase 4 with high amplitude, which strongly affects Indian rainfall.
    • Rapid Monsoon Progress: It helped push extra moisture and clouds from the Indian Ocean, making the monsoon move from Kerala to Maharashtra in just two days.
    • Other Contributing Factors:
      • A strong cross-equatorial flow brought warm, moist air from the south.
      • A low-pressure system in the Arabian Sea brought pre-monsoon rains to Mumbai.
    • Record Rainfall: This resulted in Mumbai’s wettest May in over 100 years.
    • Why It Matters: The event showed how a tropical system like the MJO can suddenly change monsoon timing and rainfall patterns in India.
    [UPSC 2017] With reference to ‘Indian Ocean Dipole (IOD)’ sometimes mentioned in the news while forecasting Indian monsoon, which of the following statements is/are correct?

    1. IOD phenomenon is characterized by a difference in sea surface temperature between tropical Western Indian Ocean and tropical Eastern Pacific Ocean.

    2. An IOD phenomenon can influence an El Nino’s impact on the monsoon.

    Options: (a) 1 only (b) 2 only* (c) Both 1 and 2 (d) Neither 1 nor 2

     

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  • Trade Sector Updates – Falling Exports, TIES, MEIS, Foreign Trade Policy, etc.

    Centre restores RoDTEP Scheme

    Prelims OnlySchemes | Economics | Mains Paper 3: Effects Of Liberalization On The Economy, Changes In Industrial Policy and their effects on Industrial Growth

    Why in the News?

    To boost India’s export strength, the government has restored Remission of Duties and Taxes on Exported Products (RoDTEP) Scheme benefits for eligible exports starting June 1, 2025.

    Details of the Latest Update:

    • RoDTEP benefits have now been restored for Advance Authorization (AA) holders, Export-Oriented Units (EOUs), and Special Economic Zones (SEZs).
    • These categories were previously excluded from February 5, 2025, but are now eligible again from June 1, 2025.
    • The move ensures a level playing field for all exporters and encourages broad-based export growth.

    About the RoDTEP Scheme:

    • Launch: It started on January 1, 2021, as part of the Foreign Trade Policy 2015–20.
    • Objective: It helps exporters get refunds for hidden taxes and duties that are not refunded under other schemes.
      • Examples of Hidden Taxes: These include taxes like electricity duty, mandi tax, and fuel charges during transport.
    • Why it was introduced: RoDTEP replaced the earlier Merchandise Export Incentive Schemes (MIES) after India lost a case at the World Trade Organisation (WTO).
    • Global Compliance: The scheme is WTO-compliant, following the rule that exported goods should not carry domestic taxes.
    • Administered by: It is managed by the Department of Revenue under the Ministry of Finance.

    Eligibility under RoDTEP:

    • Who can apply: All Indian exporters — whether manufacturers or merchant exporters — are eligible.
    • Eligible exports: Exports from SEZs, EOUs, and e-commerce platforms are also covered.
    • Not Eligible: Re-exported goods are not eligible for benefits.
    • Sector Focus: The scheme gives priority to labour-intensive sectors that earlier benefitted from MEIS.

    How the refund works:

    • Rebate Calculation: The refund is given as a percentage of the export value (Free on Board value).
    • Mode of Refund: The benefit comes in the form of e-scrips, which are stored in a digital ledger by the Central Board of Indirect Taxes and Customs (CBIC).
    • Usage of E-Scrips: These e-scrips can be used to pay basic customs duty or be transferred to other importers.
    [UPSC 2020] With reference to the international trade of India at present, which of the following statements is/are correct?

    1.  India’s merchandise exports are less than its merchandise imports.

    2. India’s imports of iron and steel, chemicals, fertilizers and machinery have decreased in recent years.

    3. India’s exports of services are more than its imports of services.

    4. India suffers from an overall trade/current account deficit.

    Select the correct answer using the code given below:

    Options: (a) 1 and 2 only  (b) 2 and 4 only (c) 3 only (d) 1, 3 and 4 only*

     

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  • GI(Geographical Indicator) Tags

    Kumbakonam Vetrilai Betel Leaf gets GI Tag

    Prelims Only | Agriculture | Mains Paper 3: Intellectual Property Rights

    Why in the News?

    The Kumbakonam Vetrilai (betel leaf or paan leaf) has received the Geographical Indication (GI) tag from the Government of India.

    About Kumbakonam Vetrilai

    • Cultivation: It is grown in the Thanjavur region, especially in Kumbakonam, Thiruvaiyaru, Papanasam, Thiruvidaimarudur, and Rajagiri.
    • Characteristics: The leaf is heart-shaped, dark to light green, with a strong aroma and pungent taste, thanks to the fertile Cauvery basin soil.
    • Cultural Importance: It is a main ingredient in paan, a popular post-meal chew in South Asia.
    • Harvest: The first-year yield, called maaruvethalai, produces the largest and longest-lasting leaves (6–7 days shelf life); Farmers hand-pick leaves, working from early morning until late night due to the labour-heavy process.

    Back2Basics: Geographical Indication (GI) Tag

    • A GI is a sign used on products that have a specific geographical origin and possess qualities or a reputation that are due to that origin.
    • Nodal Agency: Department for Promotion of Industry and Internal Trade (DPIIT), Ministry of Commerce and Industry
    • India, as a member of the World Trade Organization (WTO), enacted the Geographical Indications of Goods (Registration and Protection) Act, 1999 w.e.f. September 2003.
    • GIs have been defined under Article 22 (1) of the WTO Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS) Agreement.
    • The tag stands valid for 10 years and can be renewed.

     

    [UPSC 2015] Which of the following has/have been accorded ‘Geographical Indication’ status?

    (1) Banaras Brocades and Sarees (2) Rajasthani Daal-Bati-Churma (3) Tirupathi Laddu

    Select the correct answer using the code given below.

    Options: (a) 1 only (b) 2 and 3 only (c) 1 and 3 only* (d) 1, 2 and 3

     

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  • Wildlife Conservation Efforts

    Conservation of Dugongs

    Prelims OnlySpecies | Enviro & Biodiversity | Mains Paper 3: Conservation, Environmental Pollution & Degradation, Eia

    Why in the News?

    May 28 is celebrated every year as World Dugong Day.

    Conservation of Dugongs

    About Dugongs:

    • Species Info: Dugong dugon, also known as sea cows, are herbivorous marine mammals closely related to manatees but live only in saltwater.
    • Habitat: They live in shallow coastal waters and are mainly found in the Andaman and Nicobar Islands, Gulf of Mannar, Palk Bay, and Gulf of Kutch.
    • Diet and Role: Dugongs feed on seagrass species like Cymodocea, Halophila, Thalassia, and Halodule. As they graze, they stir up the seabed, earning the nickname “farmers of the sea.”
    • Lifespan and Behaviour: They can live up to 70 years and are usually solitary or seen in mother-calf pairs.
    • Reproduction: Females mature at 9–10 years and give birth every 3–5 years, resulting in a slow population growth of about 5% per year.
    • Conservation Concern: India’s dugong population has dropped to an estimated 200 individuals, with shrinking range and numbers.

    Conservation Efforts in India:

    • IUCN Status: Dugongs are listed as ‘Vulnerable’ globally and ‘Regionally Endangered’ in India.
    • Legal Protection: They are protected under Schedule I of the Wild Life (Protection) Act, 1972.
    • Global Agreements: India joined the Convention on Migratory Species in 1983 and signed the Dugong Conservation MoU in 2008.
    • Dugong Reserve: In 2022, India established its first Dugong Conservation Reserve in Palk Bay, Tamil Nadu, covering 448.3 sq. km.
    [UPSC 2015] With reference to ‘dugong’ a mammal found in India, which of the following statements is/are correct?

    1. It is a herbivorous marine animal. 2. It is found along the entire coast of India. 3. It is given legal protection under Schedule I of the Wildlife (Protection) Act 1972.

    Options: (a) 1 and 2 (b) 2 only (c) 1 and 3 * (d) 3 only

     

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  • Global Geological And Climatic Events

    What is Magnetic Flip-Flop?

    Prelims Only | Geography | Mains Paper 1: Important Geophysical Phenomena

    Why in the News?

    In 2024, a soundtrack was released inspired by the Laschamps event, a magnetic flip-flop that occurred 41,000 years ago when Earth’s magnetic field weakened to just 5% and the poles briefly reversed.

    What is Magnetic Flip-Flop?

    • Definition: A magnetic flip-flop is when Earth’s magnetic poles reverse, with the north and south poles switching places.
    • Magnetic Field Source: Earth’s magnetic field is generated by the movement of molten iron in the outer core, acting like a giant magnet.
    • Reversal Types:
      • A long-term change is called a geomagnetic reversal.
      • A short-lived, temporary switch is a geomagnetic excursion.
    • Field Behavior: During a reversal, the magnetic field weakens significantly and the direction of field lines flips.
    • Occurrence: These events are irregular and unpredictable.

    Recent Magnetic Reversals and Excursions:

    • Last Major Reversal: The Brunhes–Matuyama reversal occurred about 780,000 years ago.
    • Known Excursions:
      • Norwegian-Greenland Sea event (~64,500 years ago)
      • Laschamps excursion (~41,000 years ago), when field strength dropped to 5% of today’s level
      • Mono Lake excursion (~34,500 years ago)
    • Indian Evidence: Excursions found in Uttarakhand (Bagwalipokar), dated to 15,500–14,700 years and 8,000–2,850 years ago.
    • Pole Movement: Since 1831, the north magnetic pole has shifted 1,100 km toward Siberia and now moves at 35 km/year, while the south pole is more stable.

    Implications of Magnetic Flip-Flop:

    • Radiation Exposure: A weaker magnetic field during flip-flop allows more cosmic radiation, affecting:
      • Satellites and astronauts
      • Navigation and communication systems
      • Power grids and electronics
    • Protective Shield: Earth’s atmosphere still protects against harmful radiation even when the magnetic field is weak.
    • Climate & Ozone Effects: Events like Laschamps may have altered the ozone layer and climate, but no confirmed link to mass extinctions.
    • South Atlantic Anomaly: A current weak-field region affecting spacecraft over South America and South Africa.
    • Monitoring Tools: Scientists use satellites, ice cores, volcanic rocks, and geomagnetic observatories to track field changes.
    • Global Guidance: The World Magnetic Model, updated every 5 years, supports navigation systems worldwide.
    • Prediction Outlook: Though timing of future reversals is uncertain, computer models and cosmic data are improving forecasts.
    [UPSC 2017] Consider the following statements:

    1. The Earth’s magnetic field has reversed every few hundred thousand years.

    2. When the Earth was created more than 4000 million years ago, there was 54% oxygen and no carbon dioxide.

    3. When living organisms originated, they modified the early atmosphere of the Earth.

    Which of the statements given above is/are correct?

    Options: (a) 1 only (b) 2 and 3 only (c) 1 and 3 only * (d) 1, 2 and 3

     

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  • New Species of Plants and Animals Discovered

    New Cambrian sea creature Mosura fentoni discovered in Canada

    Prelims Only | Science Tech | Mains Paper 3: Awareness in various sc and tech fields

    Why in the News?

    Scientists have discovered a new sea creature from the Cambrian period named Mosura fentoni, found in Canada’s Burgess Shale, one of the most important fossil sites in the world.

    New Cambrian sea creature Mosura fentoni discovered in Canada

    About Mosura fentoni:

    • Discovery Site: Mosura fentoni was discovered in Canada’s Burgess Shale, a well-known Cambrian fossil site.
    • Biological Group: It belongs to radiodonts, an extinct group of marine predators related to insects, crabs, and spiders.
    • Size and Structure: The creature is very small (1.5 to 6 cm) but has a long, complex body made of 26 segments.
    • Body Zones:
      • The neck supports the head.
      • The mesotrunk has six paddle-shaped flaps for swimming, like mini propellers.
      • The posterotrunk has up to 16 segments with rows of thin gills and small flaps.
    • Breathing Adaptation: The gills in the posterotrunk likely acted as a breathing zone, similar to the tails of horseshoe crabs that help collect oxygen.

    Evolutionary Importance:

    • Arthropod Evolution: The find helps explain how early arthropods (like modern insects and crustaceans) evolved diverse forms.
    • Advanced Abilities: Despite its small size, M. fentoni had specialised swimming and breathing systems.
    • Evolutionary Position: It is placed near the base of the hurdiid family in the radiodont family tree.
    • Segment Specialisation: Its body shows early examples of segment division for specific tasks — a trait common in modern arthropods.
    • Key Insight: The discovery suggests that complex body planning in arthropods began much earlier than previously thought.

    Back2Basics: Cambrian Period:

    • The Cambrian Period is a division of the geologic time scale that lasted from approximately 541 million to 485 million years ago.
    • It is the first period of the Paleozoic Era and follows the Precambrian Eon.
    • It is significant because it marks a time when most major animal groups first appeared in the fossil record.
    • This period is characterized by the development of complex, multicellular life, especially in marine environments.
    • The Cambrian Explosion refers to a relatively short evolutionary event—occurring around 541 million years ago—during which a vast number of new animal species and body plans rapidly emerged.
    • Within about 20 to 25 million years, nearly all major animal phyla (like arthropods, mollusks, and chordates) appeared.
    • This explosion of biodiversity is seen as one of the most important evolutionary events in Earth’s history.

     

    [UPSC 2019] The word ‘Denisovan’ is sometimes mentioned in media in reference to-

    Options: (a) fossils of a kind of dinosaurs (b) an early human species* (c) a cave system found in North-East India. (d) a geological period in the history of Indian subcontinent

     

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