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Topic Algal Bloom
Asked 3 times across 2 UPSC exams over 27 years (1998–2025), peaking in 2011.
Key insights
- Most tested in CSE — 2 of 3 PYQs
- Most asked in 2011
- Recurs across 3 years (1998–2025)
How it travelled across exams
First appearance in each exam — the same idea, reframed.
CSE 1998 → ESE 2025
How the concept evolved
Long-running — most appearances (2 of 3) predate 2016, and it still returns.
Related concepts
Ideas UPSC tests alongside this one — keep exploring.
Sample questions
You've seen the pattern — here are a few of the actual PYQs.
ESE2025
'Algal Bloom' is, when unusually large concentrations of
- A Nutrients are present in water bodies; an excess growth of algae appears
- B Planktons are present in water bodies; an excess growth of algae appears
- C Bacteria are present in water bodies; an excess growth of algae appears
- D Oxygen is present in water bodies; an excess growth of algae appears
Answer key not yet available (pending official release)
Environment & Ecology › Pollution & Waste
CSE2011
There is a concern over the increase in harmful algal blooms in the seawaters of India. What could be the causative factors for this phenomenon?
- Discharge of nutrients from the estuaries
- Run-off from the land during the monsoon
- Upwelling in the seas
Select the correct answer from the codes given below:
- A 1 only
- B 1 and 2 only
- C 2 and 3 only
- D 1, 2 and 3 ✓
✓ Correct answer: (D)
Environment & Ecology › Pollution & Waste
CSE1998
Estuaries possess distinct blooms of excessive growth of a pigmented dinoflagellates. These blooms are called.
- A red tides ✓
- B sea tides
- C black tides
- D sea flowers
✓ Correct answer: (A)
Environment & Ecology › Ecology & Ecosystems
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