Ecosystem Fundamentals MCQs: 10 Solved Questions on Meaning and Ecological Organisation

Ecosystem questions can look like unrelated facts. Most reduce to four ideas: the ecosystem as a functional unit, relationships among organisms, gross versus net productivity, and human interaction with ecological systems. These 10 solved MCQs from the published set show the exact clue that separates each answer from its distractors.

Related reading: environmental conventions and pollution and waste management.

Ecosystem definition and ecological organisation MCQs

Start with the hierarchy: organism, population, community, ecosystem. A population consists of one species in an area, while a community brings different populations together. An ecosystem includes the community, abiotic environment, and their exchanges of energy and matter, so it functions as a unit.

Q1. Functional unit of nature (SSC CGL 2024)

Which of the following can be represented as a functional unit of nature?

• (a) Vehicles

• (b) Ecosystem

• (c) Humans

• (d) Plants

Correct answer: (b) Ecosystem.

A plant or a human is one organism, not the whole system. In a pond, algae, zooplankton, fish, decomposers, water, dissolved oxygen, minerals and sunlight interact through energy and nutrient flows. Together they form the ecosystem.

Q2. Symbiotic organisation in lichens (UPTET 2013)

Lichens are:

• (a) Parasites

• (b) Chemoautotrophs

• (c) Decomposers

• (d) Symbionts

Correct answer: (d) Symbionts.

A lichen is a stable association between a fungus and a photosynthetic partner, usually an alga or cyanobacterium. The photosynthetic partner supplies carbohydrates, while the fungus provides structure, water retention and mineral access. This reciprocal association makes symbionts the precise answer.

Q3. Restricted geographical distribution (CTET 2021)

Species restricted to a particular area are referred to as

• (a) Endangered species

• (b) Extinct species

• (c) Endemic species

• (d) Migratory species

Correct answer: (c) Endemic species.

Endemic describes geographical range within a defined region. Endangered describes extinction risk, extinct means no living individuals remain, and migratory describes regular movement. The Nilgiri tahr is a regional example because its natural distribution is geographically restricted.

Ecosystem productivity MCQs: gross, net, primary and secondary

Use two axes. Primary productivity refers to producer biomass, while secondary productivity refers to consumer biomass. Gross is before respiratory loss and net is after it: NPP = GPP - producer respiration and net secondary productivity = gross secondary productivity - consumer respiration.

Q4. Total biomass gain by an animal (UGC NET 2024)

The total gain in biomass by an animal is called

• (a) Gross primary productivity

• (b) Gross secondary productivity

• (c) Net primary productivity

• (d) Net secondary productivity

Correct answer: (b) Gross secondary productivity.

An animal is a consumer, so the relevant production is secondary rather than primary. The word total asks for the value before respiratory expenditure, which makes it gross. If an animal assimilates 600 kJ and uses 410 kJ in respiration, gross secondary productivity is 600 kJ, while net secondary productivity is 600 - 410 = 190 kJ. The clue total therefore selects 600 kJ and option (b).

Q5. Plant biomass after respiratory loss (UGC NET 2024)

The amount of biomass produced by the plants through photosynthesis minus respiration losses in a given time period is known as:

• (a) Gross Primary Productivity

• (b) Net Primary Productivity

• (c) Gross Ecological Productivity

• (d) Net Secondary Productivity

Correct answer: (b) Net Primary Productivity.

Plants make this primary productivity, and subtracting their respiration makes it net. Suppose producers fix 2,400 kJ m^-2 yr^-1 and use 900 kJ m^-2 yr^-1 in respiration. Then NPP = 2,400 - 900 = 1,500 kJ m^-2 yr^-1. This remainder is available for plant growth and transfer to the next trophic level.

For a deeper treatment of trophic transfer, lake productivity and pollution-linked concepts, continue with Ecosystem and Biomes: Energy Flow, BOD and Pollution Traps.

Ecosystem sustainability and human-response MCQs

These questions ask why ecosystems matter and how human knowledge or ethical viewpoints shape responses. Keep the ecological claim separate from the logical or philosophical label.

Q6. Himalayan ecosystem assertion and reason (UGC NET 2020)

Given below are two statements one is labelled as Assertion (A) and the other is labelled as Reason (R): Assertion (A): It is crucial to sustain Himalayan ecosystem. Reason (R): Himalayan ecosystem is home to a number of indigenous tribes. In the light of the above two statements choose the correct answer from the options given below:

• (a) Both (A) and (R) are true and (R) is the correct explanation of (A).

• (b) Both (A) and (R) are true but (R) is NOT the correct explanation of (A).

• (c) (A) is true but (R) is false.

• (d) (A) is false but (R) is true.

Correct answer: (b) Both (A) and (R) are true but (R) is NOT the correct explanation of (A).

Both statements are true, but their logical connection must also be tested. Indigenous communities are one reason to sustain the Himalayan ecosystem, while the wider justification includes biodiversity, water regulation, soils, climate interactions and livelihood systems. The reason is valid but incomplete, so option (b) fits.

Q7. Indigenous knowledge as an environmental response (UGC NET 2024)

Indigenous Knowledge and Resource Management System is at best can be considered as-

• (a) Mitigation Response

• (b) Adaptation Response

• (c) Decarbonization Response

• (d) Ethical Response

Correct answer: (b) Adaptation Response.

Local knowledge about water storage, cropping, grazing, building and seasonal signals helps communities adjust to ecological and climatic conditions. Such adjustment is adaptation. Mitigation and decarbonisation focus on reducing drivers or emissions, while ethical response is too general for the resource-management function.

Q8. Environmental ethics viewpoints (UGC NET 2025)

Major philosophical approaches to environmental ethics are : A. Anthropocentrism B. Egocentrism C. Biocentrism D. Ecocentrism Choose the correct answer from the options given below :

• (a) A, B, and D Only

• (b) A, B, C, and D

• (c) A, C, and D Only

• (d) A, B, and C Only

Correct answer: (c) A, C, and D Only.

Anthropocentrism centres human interests. Biocentrism gives moral standing to living beings, while ecocentrism considers ecological wholes such as species, communities and ecosystems. Egocentrism means self-centredness and is not a major environmental-ethics framework in this list.

Ecosystem energy balance and conservation MCQs

These fundamentals also appear in planetary energy accounting and place-based conservation. Keep the clues distinct: greenhouse warming concerns outgoing longwave radiation, while preservation protects a habitat and its species.

Q9. Greenhouse warming assertion and reason (UGC NET 2026)

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: Earth's atmosphere keeps the planet warm mainly by reflecting the incoming solar radiation. Reason R: Greenhouse gases absorb longwave radiation emitted from the earth's surface. In the light of the above statements, choose the most appropriate answer from the options given below:

• (a) Both A and R are correct and R is the correct explanation of A

• (b) Both A and R are correct but R is NOT the correct explanation of A

• (c) A is correct but R is not correct

• (d) A is not correct but R is correct

Correct answer: (d) A is not correct but R is correct.

Reflection of incoming solar radiation is not the main greenhouse mechanism, so the assertion is false. Greenhouse gases absorb and re-emit outgoing longwave radiation from Earth's surface, making the reason true. The correct truth-value combination is therefore option (d).

Q10. Silent Valley ecosystem conservation (BPSC 2023)

Silent Valley of Kerala is preserved because

• (a) It contains very rare species of plants and animals

• (b) The soil is rich in minerals

• (c) The areas of land were used extensively for agriculture purposes

• (d) More than one of the above

• (e) None of the above

Correct answer: (a) It contains very rare species of plants and animals.

Silent Valley is preserved for its ecologically rich tropical forest habitat and the rare plant and animal species it supports. Soil mineral content and extensive agricultural use are not the preservation reason stated in the question. More than one of the above also fails because only option (a) supplies the relevant conservation reason.

Ecosystem fundamentals answer map

Three elimination rules make this set easier to revise:

1. Identify the level before the quantity. Decide producer or consumer first, then gross or net.

2. Test the assertion and reason separately before asking whether the reason explains the assertion.

3. Distinguish a distribution term such as endemic from a risk term such as endangered.

How exams test ecosystem fundamentals

The set uses four recurring formats without implying weightage. Q1 to Q3 test definitions, Q4 and Q5 test two-axis terminology, Q6 and Q9 use assertion and reason, and Q7, Q8 and Q10 apply concepts to responses, ethics or conservation.

CTET-style environmental questions may place a familiar fact inside classroom, observation or region-based framing. CTET EVS Pedagogy: 6 Themes and How It Is Tested explains how content knowledge and the way a learner encounters that content can be tested together.

Ecosystem fundamentals practice: the short version and next step

Keep this four-line revision card:

• Ecosystem = biotic plus abiotic interactions.

• Primary or secondary identifies the producer or consumer level.

• Gross or net identifies before or after respiration.

• Assertion-reason questions require two truth checks followed by one explanation check.

For the full people, development and environment sequence, use the NTA UGC NET Paper 1 Course. The UGC NET CS Exam Preparation category is the wider catalogue route for related preparation areas.

Next, solve more questions in the Ecosystem Fundamentals learn module. It opens the shared topic practice area rather than a separate page for each question, so revise the four distinctions and test them across the complete set.