DU Environmental Science (AEC): Most Repeated Questions from 17 Past Papers

Environmental Science: Theory into Practice (I) (Unique Paper Code 2181001001) is an Ability Enhancement Course (AEC) that students across many DU programmes sit. The syllabus is broad and the paper is short, so the real question is what to revise first.

We took every distinct paper we have for this code (17 papers, from Nov-Dec 2023 to May-Jun 2026, with duplicate copies of the same paper removed) and counted what came back. All the papers are on the Environmental Science (I) PYQ page.

What the paper looks like now

In the May-Jun 2026 papers, students from the 2025 admission (and repeaters from 2023 and 2024) attempt only Part A: 1 hour, 30 marks.

Repeaters from 2022 also attempt Part B (20 marks, any two questions), and SOL repeaters add Part C. Part B is where the data-table questions sit.

Topics ranked by how many of the 17 papers asked them

Abbreviations: what was asked, and what it stands for

Q1(a) asked for five abbreviations in most of the recent sittings. Across those papers, SDG, GAP, AQI, BOD and NGT each came back more than once.

True or false: statements from past papers, with answers

True/false statements get recycled, and several of these were asked in more than one paper.

Fill-in-the-blank pattern to expect: the Ramsar Convention protects wetlands, pyramid of energy is always upright, loudness is measured in decibels.

Answer pointers for the top topics

These are revision prompts, not full answers. Write the full answer from your textbook and class notes.

Sustainable development. Meeting present needs without compromising the ability of future generations to meet theirs (the Brundtland definition, 1987). Three pillars: environmental, social, economic. Link to the 17 SDGs and the 3R principle (reduce, reuse, recycle).

Solid waste management. Segregation at source, collection, composting of organic waste, recycling, waste-to-energy, and sanitary landfills as the last option. Add the 3Rs and the plastic and e-waste rules, then one local example.

Renewable energy. Solar, wind, hydro, tidal, biomass and geothermal. Advantages: low emissions and regeneration. Limitations for solar: intermittency, land use, storage cost and panel waste. Never write "no impact".

Ecosystem services. Four types: provisioning (food, water), regulating (climate, flood control), supporting (nutrient cycling, soil formation) and cultural (recreation, spiritual value). Give one example for each.

Ecological succession. Primary succession starts on bare rock with no soil: pioneer species such as lichens, then mosses, herbs, shrubs and trees, ending in a climax community. Secondary succession starts where soil already exists (abandoned farmland) and is faster. For the aquatic route, describe the hydrosere: phytoplankton, submerged plants, floating plants, reed swamp, sedge meadow, woodland.

Ecological pyramids. Three types: number, biomass, energy. Energy is always upright because energy is lost at each level. Number and biomass can be inverted (a tree supporting many insects; phytoplankton supporting zooplankton in a pond).

Air pollution. Primary pollutants (SO2, NOx, CO, particulate matter) vs secondary pollutants (ground-level ozone, PAN, sulphuric acid). Effects on health, crops and buildings. Controls: ESPs and scrubbers, catalytic converters, cleaner fuels, public transport, and the National Clean Air Programme.

Environmental movements. Chipko (1973, Uttarakhand, led by Chandi Prasad Bhatt and Sunderlal Bahuguna, with women like Gaura Devi), Bishnoi (1730, Khejarli, Rajasthan), Appiko (1983, Karnataka), Silent Valley (Kerala) and Narmada Bachao Andolan. For each, give year, place, cause and outcome.

Data-table questions. Read the table first. The usual sub-parts: name the highest or lowest, calculate a percentage or total, explain two reasons, then suggest two or three measures. Practise the layout, because the marks are mostly for reading the data correctly and linking it to a concept.

How to use this in the last week

1. Learn the abbreviation table and the true/false table. Together they are 10 of the 30 marks, and the questions are the most repeated part of the paper.

2. Write one clean answer each for sustainable development, solid waste, renewable energy and ecosystem services. Those four appeared in 9 to 13 of the 17 papers each.

3. Prepare short notes on succession, pyramids, and one environmental movement. The short-note question is usually drawn from these.

4. Do one data-table question from Nov-Dec 2025 or May-Jun 2026 under time.

Past repetition does not guarantee what comes next. Use this list to decide what to revise first, not what to skip.

Get the papers: Environmental Science (I) PYQs · all AEC papers

Also read: AEC courses in DU: complete guide · How to write high-scoring answers in DU exams