Let us solve a PYQ from UPSC Prelims 2017 paper - Which of the following is geographically closest to Great Nicobar?
(a) Sumatra
(b) Borneo
(c) Java
(d) Sri Lanka

Sumatra (Indonesia) is directly south/southeast of Great Nicobar, separated by the Great Channel (also called Six Degree Channel).

The shortest distance is approximately 145–180 km (some sources mention around 150 km between Indira Point and Aceh Head/Rondo Island in northern Sumatra).

Let us discuss -

Caspian sea is World’s largest inland body of water, often called the world’s largest lake or largest salt lake, though named a “sea”.

Does UNCLOS applies?

Let me know.

• No, UNCLOS does not apply to the Caspian Sea.
• UNCLOS (United Nations Convention on the Law of the Sea, 1982) primarily governs marine spaces connected to the oceans.
• The 2018 Convention on the Legal Status of the Caspian Sea (signed in Aktau, Kazakhstan) gives it a special/sui generis legal status; it is deliberately neither classified as a sea nor as a lake.
• This convention creates its own regime: 15 nautical miles of territorial waters + 10 nautical miles of exclusive fishing zone for each of the five littoral states (Russia, Azerbaijan, Kazakhstan, Turkmenistan, Iran).
• The seabed resources are to be delimited by bilateral/multilateral agreements among them.

2 Facts to know about Green Turtle -

For UPSC Prelims -

Green turtles were recently downlisted from Endangered to Least Concern globally.

The diet of Green sea turtles changes with age.
Juveniles are carnivorous, but as they mature they become herbivorous, infact, they play a key ecological role as “gardeners” of seagrass meadows, their grazing helps maintain healthy underwater ecosystems that support fish and other marine life.

Follow up question -

Difference between Seaweeds v/s Seagrasses

Sea weeds are macroalgae and Seagrasses are marine flowering plants.

Another question-
Who are the pollinators of seagrasses?

Let us discuss Dudhwa TR. Can you share the Big 5 of Dudhwa?

Let us compare these species of Dudhwa Big 5 with Kaziranga Big 5?

Leopard numbers have surged dramatically to 93+ in Dudhwa TR. (as of 2025, up from 34 in 2022).
The 2025 Triennial Survey of Dudhwa Tiger Reserve (DTR) is the latest state-level wildlife population estimation exercise conducted every 3 years by the Uttar Pradesh Forest Department.

Another question
How many tiger reserves are there in UP?

There are three tiger reserves in UP.
Amangarh is the buffer zone of Corbett in UK.

Not counted as a tiger reserve per se in the 58 TRs of India.

Another important fact is regarding Katarniaghat Wildlife Sanctuary - Girwa river being an important breeding ground for Gharials.

KWS being a part of core of DTR.

Gharial is Critically endangered fish eating fresh water crocodile.

Girwa river is a tributary of which river ?

Two TRs of UP, Dudhwa and Pilibhit are in TAL wheres Ranipur is in dry deciduous forest region on the southern border.

Do you guys want to revise BRs today?

Two PYQs to begin with –
Prelims 2018
1. Which of the following are in Agasthyamala Biosphere Reserve?
(a)Neyyar, Peppara and Shendurney Wildlife Sanctuaries; and Kalakad Mundanthurai Tiger Reserve
(b)Mudumalai, Sathyamangalam and Wayanand Wildlife Sanctuaries; and Silent Valley National Park
(c)Kaundinya, Gundla Brahmeswaram and Papikonda Wildlife Sanctuaries; and Mukurthi National Park
(d)Kawal and Sri Venkateswara Wildlife Sanctuaries; and Nagarjunasagar-Srisailam Tiger Reserve
Prelims 2020
2. Which of the following Protected Areas are located in Cauvery basin?
1. Nagarhole National park
2. Papikonda National Park
3. Sathyamagalam Tiger Reserve
4. Wayanand Wildlife Sanctuary
Select the correct answer using the code given below:
(a) 1 and 2 only
(b) 3 and 4 only
(c) 1, 3 and 4 only
(d) 1, 2, 3 and 4

India has 18 notified biosphere reserves, which are large areas of terrestrial, coastal, or marine ecosystems designated by the Ministry of Environment, Forest and Climate Change to conserve biodiversity while promoting sustainable development and supporting local communities.
These reserves often include core zones (strictly protected), buffer zones, and transition zones.
Of these, 13 are internationally recognized as part of UNESCO’s World Network of Biosphere Reserves (WNBR) under the Man and the Biosphere (MAB) Programme.
The 5 non-UNESCO reserves (Manas, Dibru-Saikhowa, Dihang-Dibang, Great Rann of Kutch, Seshachalam) are nationally notified and under consideration for WNBR inclusion. MRS D2

Nilgiri is the only one shared by three states.
Agasthyamalai and Achanakmar-Amarkantak are shared by two states.

Great Rann of Kutch is the largest.
Dibru-Saikhowa is the smallest.

Which is the latest BR to be added to WNBR, and is famous for which species?