Ecosystem – Daily Practice Problem (DPP)

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🎯 NEET 2026 Daily Practice Problem (DPP)

Class 12 | Unit 5: Ecology | Topic: Ecosystem

Q1. Vertical distribution of different species occupying different levels is called:

  1. Stratification
  2. Eutrophication
  3. Productivity
  4. Succession
✅ View Answer & Explanation

Correct Answer: (1) Stratification
Explanation: For example, in a forest, trees occupy the top vertical strata, shrubs the second, and herbs/grasses the bottom layers.

Q2. Which of the following is NOT a functional unit of an ecosystem?

  1. Energy flow
  2. Decomposition
  3. Productivity
  4. Stratification
✅ View Answer & Explanation

Correct Answer: (4) Stratification
Explanation: Stratification is a structural aspect. The four functional aspects are Productivity, Decomposition, Energy flow, and Nutrient cycling.

Q3. Net Primary Productivity (NPP) is defined as:

  1. GPP + Respiration Loss (R)
  2. GPP – Respiration Loss (R)
  3. Secondary Productivity – R
  4. Rate of formation of new organic matter by consumers
✅ View Answer & Explanation

Correct Answer: (2) GPP – Respiration Loss (R)
Explanation: Gross Primary Productivity (GPP) minus respiration losses (R) is the Net Primary Productivity (NPP), which is the biomass available for consumers.

Q4. The rate of decomposition is slower if detritus is rich in:

  1. Nitrogen and water-soluble substances
  2. Sugars and nitrogen
  3. Lignin and Chitin
  4. Cellulose and sugar
✅ View Answer & Explanation

Correct Answer: (3) Lignin and Chitin
Explanation: Decomposition is quicker if detritus is rich in nitrogen and water-soluble substances (like sugars) and slower if rich in lignin and chitin.

Q5. Which step of decomposition involves water-soluble inorganic nutrients going down into the soil horizon?

  1. Fragmentation
  2. Leaching
  3. Catabolism
  4. Humification
✅ View Answer & Explanation

Correct Answer: (2) Leaching
Explanation: By leaching, water-soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts.

Q6. How much of the incident solar radiation is Photosynthetically Active Radiation (PAR)?

  1. Less than 50%
  2. More than 80%
  3. About 10%
  4. 1-5%
✅ View Answer & Explanation

Correct Answer: (1) Less than 50%
Explanation: Of the incident solar radiation, less than 50% is PAR. Plants capture only 2-10% of PAR.

Q7. The 10% law of energy transfer was proposed by:

  1. Lindeman
  2. Tansley
  3. Elton
  4. Odum
✅ View Answer & Explanation

Correct Answer: (1) Lindeman
Explanation: Only 10% of the energy is transferred to the next higher trophic level; the rest is lost as heat (Respiration).

Q8. Which ecological pyramid is always upright?

  1. Pyramid of Number
  2. Pyramid of Biomass
  3. Pyramid of Energy
  4. Both 1 and 2
✅ View Answer & Explanation

Correct Answer: (3) Pyramid of Energy
Explanation: Energy flow is unidirectional and always decreases at successive trophic levels due to heat loss, so the pyramid is always upright.

Q9. In an aquatic ecosystem (e.g., sea), the pyramid of biomass is generally:

  1. Upright
  2. Inverted
  3. Spindle-shaped
  4. Bell-shaped
✅ View Answer & Explanation

Correct Answer: (2) Inverted
Explanation: The biomass of producers (phytoplankton) is much less than that of consumers (zooplankton/fishes), yet the producers reproduce fast enough to support the chain.

Q10. The gradual and fairly predictable change in the species composition of a given area is called:

  1. Ecological Niche
  2. Ecological Succession
  3. Stratification
  4. Bioaccumulation
✅ View Answer & Explanation

Correct Answer: (2) Ecological Succession
Explanation: Succession leads to a community that is in near equilibrium with the environment, called a climax community.

Q11. The pioneer species in a Xerarch succession (on bare rock) are usually:

  1. Phytoplankton
  2. Bryophytes
  3. Lichens
  4. Herbs
✅ View Answer & Explanation

Correct Answer: (3) Lichens
Explanation: Lichens secrete acids to dissolve rock, helping in weathering and soil formation.

Q12. Secondary succession begins in areas:

  1. Where no living organisms ever existed
  2. Of bare rock
  3. Where natural biotic communities have been destroyed
  4. Newly created pond
✅ View Answer & Explanation

Correct Answer: (3) Where natural biotic communities have been destroyed
Explanation: Examples include abandoned farm lands, burned or cut forests. Since soil is already present, it is faster than primary succession.

Q13. Both hydrarch and xerarch successions lead to:

  1. Medium water conditions (Mesic)
  2. Xeric conditions
  3. Hydric conditions
  4. Extremely dry conditions
✅ View Answer & Explanation

Correct Answer: (1) Medium water conditions (Mesic)
Explanation: Successions proceed to a mesic community, neither too dry (xeric) nor too wet (hydric).

Q14. The reservoir for the Phosphorus cycle is:

  1. Atmosphere
  2. Ocean water
  3. Earth’s crust (Rocks)
  4. Fossil fuels
✅ View Answer & Explanation

Correct Answer: (3) Earth’s crust (Rocks)
Explanation: The phosphorus cycle is a sedimentary cycle. The reservoir is rock, containing phosphorus in the form of phosphates.

Q15. The reservoir for the Carbon cycle is primarily located in:

  1. Atmosphere
  2. Ocean
  3. Plants
  4. Coal mines
✅ View Answer & Explanation

Correct Answer: (2) Ocean
Explanation: 71% of global carbon is found dissolved in oceans. The atmosphere contains only about 1%.

Q16. According to Robert Costanza, which ecosystem service accounts for about 50% of the total price tag?

  1. Recreation
  2. Nutrient cycling
  3. Soil formation
  4. Climate regulation
✅ View Answer & Explanation

Correct Answer: (3) Soil formation
Explanation: Soil formation accounts for about 50%, while recreation and nutrient cycling are less than 10% each.

Q17. Detritivores break down detritus into smaller particles. This process is called:

  1. Humification
  2. Fragmentation
  3. Leaching
  4. Catabolism
✅ View Answer & Explanation

Correct Answer: (2) Fragmentation
Explanation: Earthworms are examples of detritivores that perform fragmentation.

Q18. The mass of living material at a trophic level at a particular time is called:

  1. Standing crop
  2. Standing state
  3. Net primary productivity
  4. Gross primary productivity
✅ View Answer & Explanation

Correct Answer: (1) Standing crop
Explanation: Standing crop is measured as biomass or number in a unit area. ‘Standing state’ refers to the amount of nutrients in the soil.

Q19. Which of the following is a sedimentary cycle?

  1. Carbon cycle
  2. Nitrogen cycle
  3. Sulphur cycle
  4. Water cycle
✅ View Answer & Explanation

Correct Answer: (3) Sulphur cycle
Explanation: Sulphur and Phosphorus cycles are sedimentary. Carbon, Nitrogen, and Water cycles are gaseous.

Q20. In the equation GPP – R = NPP, R represents:

  1. Reproduction
  2. Respiration losses
  3. Radiation
  4. Retardation factor
✅ View Answer & Explanation

Correct Answer: (2) Respiration losses
Explanation: R stands for Respiration losses, the energy consumed by the producers for their own metabolic activities.

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