class (Cnidaria) as jellyfish and anemones. They consist of individual polyps that get together and build reefs.
Significance:
- Coral reefs support a wide range of species and maintain the quality of the coastal biosphere.
- Corals control the level of carbon dioxide in the water by converting it into a limestone shell. If this process does not take place, the amount of carbon dioxide in the ocean water would increase significantly and affect ecological niches.
Threats:
- Coral reefs are threatened by climate change.
- When the sea surface temperature increases beyond a tolerable limit, they undergo a process of bleaching.
What is bleaching?
Basically bleaching is when the corals expel a certain algae known as zooxanthellae, which lives in the tissues of the coral in a symbiotic relationship. About 90% of the energy of the coral is provided by the zooxanthellae which are endowed with chlorophyll and other pigments. They are responsible for the yellow or reddish brown colours of the host coral. In addition the zooxanthellae can live as endosymbionts with jellyfish also.
When a coral bleaches, it does not die but comes pretty close to it. Some of the corals may survive the experience and recover once the sea surface temperature returns to normal levels.
Sources: Down to Earth.
Paper 3:
Topics Covered:
- Indian Economy and issues relating to planning, mobilization of resources, growth, development and employment.
What to study?
For Prelims: Currency chest- features.
For Mains: Need and significance.
Context: The Reserve Bank of India is planning to allow large modern currency chests to increase the service charges on cash deposited by non-chest bank branches from the existing rate of ₹5 per packet of 100 pieces to a higher rate subject to a maximum of ₹8 per packet. For this, only a currency chest (CC) that fulfils the minimum standards will be eligible to be classified as a large modern CC.
What are Currency chests?
Currency chests are branches of selected banks authorised by the RBI to stock rupee notes and coins.
Who determines the number of notes and coins to be printed?
The responsibility for managing the currency in circulation is vested in the RBI.
- The central bank advises the Centre on the number of notes to be printed, the currency denominations, security features and so on. The number of notes that need to be printed is determined using a statistical model that takes the pace of economic growth, rate of inflation and the replacement rate of soiled notes.
- The Government has, however, reserved the right to determine the amount of coins that have to be minted.
Role of currency chests:
- The RBI offices in various cities receive the notes from note presses and coins from the mints. These are sent to the currency chests and small coin depots from where they are distributed to bank branches.
- The RBI has set up over 4,075 currency chests all over the country. Besides these, there are around 3,746 bank branches that act as small coin depots to stock small coins.
Reserve Bank of India (RBI) recently issued new guidelines for banks to set up new currency chests. They include:
- Area of the strong room/ vault of at least 1,500 sq ft. For those situated in hilly/ inaccessible places, the strong room/ vault area of at least 600 sq ft.
- The new chests should have a processing capacity of 6.6 lakh pieces of banknotes per day. Those situated in the hilly/ inaccessible places, a capacity of 2.1 lakh pieces of banknotes per day.
- The currency chests should have Chest Balance Limit (CBL) of Rs 1,000 crore, subject to ground realities and reasonable restrictions, at the discretion of the Reserve Bank.
Sources: the Hindu.
Paper 3:
Topic covered:
- Awareness in space.
What to study?
For Prelims and Mains: Ke features, objectives and significance of the mission.
Context: NASA has unveiled the calendar for the “Artemis” program that will return astronauts to the Moon for the first time in half a century, including eight scheduled launches and a mini-station in lunar orbit by 2024.
Key facts:
- Artemis 1 will be an uncrewed mission around the Moon planned for 2020.
- Next will come Artemis 2, which will orbit Earth’s satellite with a crew around 2022; followed finally by Artemis 3 that will put astronauts on lunar soil in 2024, including the first woman.
- The three will be launched into space by the biggest rocket of all time, the Boeing-led Space Launch System (SLS), which is currently under development but has seen numerous delays and has been criticized in some quarters as a bloated jobs program.
About Artemis:
NASA’s next mission to the Moon will be called Artemis. ARTEMIS stands for Acceleration, Reconnection, Turbulence and Electrodynamics of Moon’s Interaction with the Sun.
The mission was named Artemis after the Greek mythological goddess of the Moon and twin sister to Apollo, namesake of the program that sent 12 American astronauts to the Moon between 1969 and 1972.
Objective: It consists of spacecraft to measure what happens when the Sun’s radiation hits our rocky moon, where there is no magnetic field to protect it.
Background: The ARTEMIS mission uses two of the five in-orbit spacecraft from another NASA Heliophysics constellation of satellites (THEMIS) that were launched in 2007 and successfully completed their mission earlier in 2010. The ARTEMIS mission allowed NASA to repurpose two in-orbit spacecraft to extend their useful science mission, saving tens of millions of taxpayer dollars instead of building and launching new spacecraft.
Sources: toi.
Facts for Prelims:
‘Shaheen-II’:
What is it? It is a land-based ballistic missile of Pakistan.
- Shaheen missile series is named after a Falcon (bird) species that lives in Pakistan’s mountains.
- It is a land-based supersonic intermediate-range surface-to-surface guided ballistic missile.
- It is capable of carrying all kinds of warheads i.e. both conventional (high explosive) as well as nuclear warheads.
- It is capable of hitting targets up to 1,500-2000 kilometers. Thus is capable of reaching major cities in neighbouring India.
The white-throated rail.
Context: New research has found that the white-throated rail had once gone extinct, but rose from the dead thanks to a rare process called “iterative evolution”.- Iterative evolution means the repeated evolution of similar or parallel structures from the same ancestor but at different times.
- The white-throated rail is the only flightless bird known in the Indian Ocean area. It is a chicken-sized bird, indigenous to Madagascar. Migrating to Aldabra, the rails evolved so that they lost the ability to fly.
Milan Tomic
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