Biology — Ecology & Environment for the NEET Exam

Common failure modes

These are the patterns that cause most candidates to lose marks on this topic. Recognising them in advance is half the work.

• !Confusing ecological pyramids of number vs biomass vs energy — the pyramid of energy is always upright; others can be inverted
• !Misidentifying the India-specific biodiversity hotspots (Western Ghats and Eastern Himalayas are the two Indian hotspots)
• !Confusing primary succession (starts on bare rock) with secondary succession (starts on disturbed but soil-containing land)
• !Mixing up in situ vs ex situ conservation — zoos and seed banks are ex situ; national parks are in situ

Study tips

• 1Read NCERT Class 12 Chapters 13 (Organisms and Populations), 14 (Ecosystem), 15 (Biodiversity and Conservation), and 16 (Environmental Issues) in sequence.
• 2Memorise the 35 biodiversity hotspots worldwide; know that India has two (Western Ghats + Sri Lanka, and Indo-Burma region including Eastern Himalayas).
• 3Make a table of ecological pyramids: upright vs inverted, which model (grassland, forest, aquatic) shows each shape.
• 4For environmental issues, know the numerical data: ozone depletion by CFCs, CO₂ level changes, BOD in water pollution. NEET sometimes asks specific values.
• 5Learn the major national parks, sanctuaries, and biosphere reserves in India — 1–2 questions appear on these in most NEET papers.

Sample NEET Biology — Ecology & Environment questions

These sample items mirror the format and difficulty of real NEET questions. Practice with thousands more on the free Koydo question bank.

1. 1

   Which of the following ecological pyramids is always upright and never inverted?

   • APyramid of numbers
   • BPyramid of biomass in an aquatic ecosystem
   • CPyramid of energyCorrect
   • DPyramid of numbers in a parasitic food chain
   Why this answer?

   The pyramid of energy is always upright because energy decreases at each successive trophic level (10% rule — only 10% is transferred). Pyramids of number and biomass can be inverted (e.g., many insects on a single tree; phytoplankton biomass below zooplankton in some aquatic systems).

2. 2

   In situ conservation of biodiversity involves:

   • AMaintaining organisms in zoological parks
   • BPreserving seeds in gene banks
   • CConserving organisms in their natural habitat (e.g., national parks)Correct
   • DTissue culture of endangered plants
   Why this answer?

   In situ conservation means protecting biodiversity within the natural ecosystem and habitat — examples include wildlife sanctuaries, national parks, biosphere reserves, and sacred groves. Ex situ conservation (zoos, seed banks, botanical gardens, tissue culture) protects organisms outside their natural habitat.

3. 3

   Ozone depletion in the stratosphere is primarily caused by:

   • ACarbon dioxide (CO₂)
   • BChlorofluorocarbons (CFCs)Correct
   • CNitrous oxide (N₂O)
   • DMethane (CH₄)
   Why this answer?

   CFCs (chlorofluorocarbons) release Cl· radicals in the stratosphere under UV radiation. These Cl· radicals catalytically destroy ozone: Cl· + O₃ → ClO· + O₂. One CFC molecule can destroy thousands of ozone molecules. This is directly from NCERT Class 12 Chapter 16.