Andes Mountains & Map-Based Questions in UPSC Prelims 2025

Map-based questions are no longer occasional in UPSC Prelims — they are now regular and decisive.
In the UPSC Prelims 2025 Geography paper, nearly 5–6 questions required solid world map understanding. One such question, based on the Andes Mountains, exposed a common weakness among aspirants: mechanical memorisation without atlas clarity.

Let’s break down that question and, more importantly, the concept behind it.

The UPSC Prelims 2025 Question on Andes Mountains

Question (simplified):
The Andes Mountains pass through how many of the following countries?

• Bolivia
• Colombia
• Brazil
• Ecuador
• Paraguay
• Venezuela

At first glance, this looks easy. But the real challenge lies in border confusion, especially with countries like Brazil and Paraguay.

Countries Through Which the Andes Mountains Pass

Using a proper world physical map, the Andes Mountains clearly pass through:

• Colombia
• Ecuador
• Bolivia
• Venezuela (northern extension)

These four countries are part of the Andean mountain system.

Why Venezuela Counts

Many aspirants get confused here. While most of Venezuela is part of the Guiana Highlands, the northern portion of the Andes does extend into Venezuela. UPSC expects this finer geographic awareness.

Why Brazil Is NOT an Andes Country

This is where most mistakes happen.

Brazil does not have the Andes Mountains.

Instead, Brazil consists of three major physiographic divisions:

1. Amazon Basin
2. Guiana Highlands (northern Brazil)
3. Brazilian Highlands / Brazilian Plateau

None of these are part of the Andes mountain system.

So even though Brazil shares borders with Andean countries, the Andes do not pass through Brazil.

Why Paraguay Is Also Incorrect

Paraguay is a landlocked country dominated by:

• The Paraguay–Paraná River Basin
• Flat basin topography

It lies far east of the Andes and has no mountain extension from the Andes.
Its capital Asunción is a river port, reinforcing that Paraguay is basin-dominated, not mountainous.

Final Answer to the UPSC Question

Countries through which the Andes Mountains pass:

• Bolivia ✅
• Colombia ✅
• Ecuador ✅
• Venezuela ✅

Correct answer: 4 countries

The Bigger UPSC Lesson: How to Prepare Map-Based Questions

This question wasn’t about memory. It was about:

• Understanding mountain continuity
• Knowing physiographic divisions
• Practising with a proper atlas, not lists

What UPSC is Testing

• Conceptual clarity in world geography
• Ability to eliminate options using maps
• Integration of physical geography with spatial awareness

This is why daily atlas work is no longer optional for Prelims.

How to Practice Map-Based Geography for UPSC

• Use a physical world map, not political maps alone
• Trace mountain ranges manually
• Compare mountains vs plateaus vs basins
• Always ask: Does the landform actually pass through the country, or just border it?

That single question can save marks.

Check out our GS Geography Course – Click Here

FAQs

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