functions of an ecosystem upsc quiz

Functions of an Ecosystem UPSC

The functions of an ecosystem encompass the movement of energy, cycling of nutrients, and complex interactions among biotic and abiotic components. This includes processes such as energy flow through trophic levels, different types of food chains, ecological pyramids, biogeochemical cycles, biotic interactions, and ecological succession. Understanding these processes is crucial for grasping how ecosystems maintain balance, respond to disturbances, and support life.

This advanced quiz is designed to test your conceptual clarity and application skills for competitive exams like UPSC, State PCS, and other environment-related tests. The questions range from medium to hard difficulty, including statement-based MCQs, match-the-following, and conceptual problem-solving. Detailed explanations are provided for each question to ensure deeper understanding.

In an ecosystem, the flow of energy is:

A) Cyclic

B) Unidirectional

C) Multidirectional

D) Bidirectional

Consider the following statements regarding Lindeman’s 10% law: 1. Only around 10% of the energy is transferred from one trophic level to the next. 2. Energy efficiency between trophic levels can sometimes exceed 20% in certain ecosystems. 3. The law explains why food chains are short. Which of the statements given above is/are correct?

A) 1 and 3 only

B) 2 and 3 only

C) 1 and 2 only

D) 1, 2, and 3

Match the type of food chain with its correct starting point: Type of Food Chain Starting Point a) Grazing 1) Dead organic matter b) Detritus 2) Living green plants c) Parasitic 3) Body of a living host Select the correct code:

A) a-2, b-1, c-3

B) a-1, b-2, c-3

C) a-3, b-2, c-1

D) a-2, b-3, c-1

Which trophic level is most affected by biomagnification of persistent pollutants like mercury?

A) Producers

B) Primary consumers

C) Secondary consumers

D) Tertiary consumers

Consider the following statements regarding ecological pyramids: 1. The pyramid of energy is always upright. 2. The pyramid of biomass is always upright in terrestrial ecosystems. 3. The pyramid of numbers can be inverted. Which of the above is/are correct?

A) 1 and 2 only

B) 1 and 3 only

C) 2 and 3 only

D) 1, 2, and 3

In the phosphorus cycle, the major reservoir is:

A) Atmosphere

B) Ocean surface water

C) Sedimentary rocks

D) Forest biomass

Statement-I: The nitrogen cycle involves both fixation and denitrification. Statement-II: Denitrification converts nitrates into nitrogen gas, completing the nitrogen cycle.

A) Both statements are correct, and Statement-II is the correct explanation of Statement-I.

B) Both statements are correct, but Statement-II is not the correct explanation of Statement-I.

C) Statement-I is correct, Statement-II is incorrect.

D) Statement-I is incorrect, Statement-II is correct.

Which of the following is the correct sequence in primary ecological succession on bare rock?

A) Lichens → Mosses → Herbs → Shrubs → Trees

B) Mosses → Lichens → Herbs → Trees → Shrubs

C) Lichens → Herbs → Mosses → Shrubs → Trees

D) Mosses → Herbs → Shrubs → Lichens → Trees

In which of the following ecosystems can the pyramid of biomass be inverted?

A) Grassland

B) Tropical rainforest

C) Open ocean

D) Desert

Which nutrient cycle is most impacted by acid rain?

A) Carbon cycle

B) Sulphur cycle

C) Phosphorus cycle

D) Water cycle

Consider the following statements about the water (hydrological) cycle: 1. It is a perfect example of a gaseous cycle. 2. The main driving force is solar energy. 3. Transpiration plays a major role in water vapour release into the atmosphere. Which of the above statements are correct?

A) 1 and 2 only

B) 2 and 3 only

C) 1 and 3 only

D) 1, 2, and 3

Statement-I: Primary productivity is the rate at which organic matter is produced by producers. Statement-II: Net primary productivity (NPP) is always higher than gross primary productivity (GPP).

A) Both statements are correct, and Statement-II is the correct explanation of Statement-I.

B) Both statements are correct, but Statement-II is not the correct explanation of Statement-I.

C) Statement-I is correct, Statement-II is incorrect.

D) Statement-I is incorrect, Statement-II is correct.

Match the biotic interaction with the correct example: Interaction Example a) Mutualism 1) Mycorrhizae and plants b) Commensalism 2) Barnacles on whales c) Amensalism 3) Penicillium and bacteria d) Parasitism 4) Tapeworm in humans Select the correct code:

A) a-1, b-2, c-3, d-4

B) a-2, b-1, c-4, d-3

C) a-3, b-1, c-2, d-4

D) a-1, b-3, c-2, d-4

Consider the following regarding secondary succession: 1. Soil is already present. 2. It is slower than primary succession. 3. It can be seen after forest fires or abandoned farms. Which are correct?

A) 1 and 3 only

B) 1 and 2 only

C) 2 and 3 only

D) 1, 2, and 3

Which cycle among the following is entirely sedimentary?

A) Phosphorus cycle

B) Sulphur cycle

C) Carbon cycle

D) Nitrogen cycle

In an aquatic ecosystem, primary productivity is limited most by:

A) Light penetration and nutrients

B) Dissolved oxygen

C) Predator population

D) Water temperature alone

Statement-I: In the carbon cycle, oceans act as both source and sink. Statement-II: Oceanic phytoplankton play a major role in global carbon fixation.

A) Both statements are correct, and Statement-II is the correct explanation of Statement-I.

B) Both statements are correct, but Statement-II is not the correct explanation of Statement-I.

C) Statement-I is correct, Statement-II is incorrect.

D) Statement-I is incorrect, Statement-II is correct.

Arrange the following in correct order for nitrogen cycle processes: 1. Nitrification 2. Nitrogen fixation 3. Ammonification 4. Denitrification

A) 2 → 3 → 1 → 4

B) 3 → 2 → 1 → 4

C) 2 → 1 → 3 → 4

D) 4 → 1 → 3 → 2

Consider the following regarding detritus food chain: 1. It starts with decomposers. 2. It can connect with the grazing food chain. 3. It plays a role in nutrient recycling. Which are correct?

A) 1 and 2 only

B) 2 and 3 only

C) 1 and 3 only

D) 1, 2, and 3

Which of the following statements is correct about ecological efficiency?

A) It is the ratio of energy stored in biomass at one trophic level to energy stored at the previous level.

B) It is the same for all trophic levels.

C) It always exceeds 50%.

D) It has no effect on the length of the food chain

Functions of an Ecosystem UPSC

Functions of an Ecosystem UPSC

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