Class 12 Biology MCQ Chapter 14 Ecosystem English Medium
Are you searching for Class 12 Biology MCQ Chapter 14 Ecosystem English Medium? Then you have come to the right place. This article provides important multiple-choice questions (MCQs) with answers from Chapter 14: Ecosystem for AHSEC Higher Secondary students.
This chapter helps students understand the structure and functions of ecosystems and the relationship between living organisms and their environment. It covers important topics such as ecosystem components, food chains, food webs, ecological pyramids, energy flow, productivity, nutrient cycling, decomposition, and ecological succession. These concepts are essential for understanding how nature maintains balance and supports life on Earth.
All MCQs are prepared according to the latest AHSEC syllabus and examination pattern. Regular practice of these objective questions will help students revise important topics, improve conceptual understanding, and perform better in examinations.
Whether you are preparing for class tests, model examinations, or the AHSEC Higher Secondary Final Examination, these MCQ solutions will help you strengthen your Biology preparation and score higher marks.
Unit X: Ecology
Ecosystem English Medium
VSA & MCQ
I. Very Short Question-Answers
Q. What is an ecosystem?
Ans: An ecosystem is a functional unit of nature where living organisms interact with one another and with the physical environment.
Q. Name the two main components of an ecosystem.
Ans: Biotic components and abiotic components are the two main components of an ecosystem.
Q. What are biotic components?
Ans: Biotic components are the living organisms present in an ecosystem.
Q. What are abiotic components?
Ans: Abiotic components are the non-living factors of an ecosystem.
Q. Define producers.
Ans: Producers are autotrophic organisms that prepare food by photosynthesis.
Q. Who are consumers?
Ans: Consumers are organisms that depend on other organisms for food.
Q. What are decomposers?
Ans: Decomposers are organisms that break down dead organic matter.
Q. Name the main decomposers in an ecosystem.
Ans: Bacteria and fungi are the main decomposers.
Q. Define food chain.
Ans: A food chain is a sequence of organisms through which energy passes.
Q. What is a food web?
Ans: A food web is a network of interconnected food chains.
Q. Define trophic level.
Ans: Trophic level is each step in a food chain.
Q. What is grazing food chain?
Ans: Grazing food chain starts from green plants and passes through herbivores to carnivores.
Q. What is detritus food chain?
Ans: Detritus food chain starts from dead organic matter.
Q. Define ecological pyramid.
Ans: Ecological pyramid is a graphical representation of trophic levels.
Q. Name the three ecological pyramids.
Ans: Pyramid of number, pyramid of biomass and pyramid of energy.
Q. Which ecological pyramid is always upright?
Ans: Pyramid of energy is always upright.
Q. What is standing crop?
Ans: Standing crop is the amount of living biomass at a trophic level.
Q. Define standing state.
Ans: Standing state is the amount of inorganic nutrients present in an ecosystem.
Q. What is ecological succession?
Ans: Ecological succession is the gradual change in species composition in an area over time.
Q. What is primary succession?
Ans: Primary succession occurs in an area where no life existed previously.
Q. What is secondary succession?
Ans: Secondary succession occurs in an area where life existed earlier.
Q. Define pioneer species.
Ans: Pioneer species are the first organisms to colonize a barren area.
Q. Name the pioneer species in xerarch succession.
Ans: Lichens are the pioneer species in xerarch succession.
Q. What is climax community?
Ans: Climax community is the stable final community in succession.
Q. Define decomposition.
Ans: Decomposition is the breakdown of dead organic matter into simpler substances.
Q. Name the steps of decomposition.
Ans: Fragmentation, leaching, catabolism, humification and mineralisation are the steps of decomposition.
Q. What is humification?
Ans: Humification is the formation of dark coloured humus from decomposed organic matter.
Q. What is mineralisation?
Ans: Mineralisation is the release of inorganic nutrients from humus.
Q. State the 10% law.
Ans: According to the 10% law, only 10% of energy is transferred to the next trophic level.
Q. Who proposed the 10% law?
Ans: Raymond Lindeman proposed the 10% law.
II. Multiple Choice Questions (MCQs)
Q. An ecosystem consists of:
(a) Plants only
(b) Animals only
(c) Living and non-living components
(d) Microorganisms only
Ans: (c) Living and non-living components
Q. Green plants in an ecosystem are:
(a) Consumers
(b) Producers
(c) Decomposers
(d) Parasites
Ans: (b) Producers
Q. The organisms that break down dead matter are:
(a) Producers
(b) Herbivores
(c) Carnivores
(d) Decomposers
Ans: (d) Decomposers
Q. Which of the following is a decomposer?
(a) Grass
(b) Tiger
(c) Fungus
(d) Deer
Ans: (c) Fungus
Q. A food chain represents:
(a) Reproductive relationship
(b) Energy flow
(c) Water cycle
(d) Respiration
Ans: (b) Energy flow
Q. Interconnected food chains form:
(a) Trophic level
(b) Ecological pyramid
(c) Food web
(d) Biomass
Ans: (c) Food web
Q. The first trophic level is occupied by:
(a) Carnivores
(b) Herbivores
(c) Producers
(d) Decomposers
Ans: (c) Producers
Q. Herbivores belong to:
(a) First trophic level
(b) Second trophic level
(c) Third trophic level
(d) Fourth trophic level
Ans: (b) Second trophic level
Q. The pyramid of energy is always:
(a) Inverted
(b) Circular
(c) Upright
(d) Horizontal
Ans: (c) Upright
Q. According to the 10% law, energy transferred to next trophic level is:
(a) 1%
(b) 5%
(c) 10%
(d) 20%
Ans: (c) 10%
Q. The amount of living material at a trophic level is called:
(a) Standing state
(b) Standing crop
(c) Biomagnification
(d) Mineralisation
Ans: (b) Standing crop
Q. Ecological succession begins with:
(a) Climax species
(b) Consumers
(c) Pioneer species
(d) Parasites
Ans: (c) Pioneer species
Q. Lichens are pioneer species in:
(a) Hydrarch succession
(b) Xerarch succession
(c) Secondary succession
(d) Grassland succession
Ans: (b) Xerarch succession
Q. The final stable stage of succession is:
(a) Pioneer stage
(b) Seral stage
(c) Climax community
(d) Community pool
Ans: (c) Climax community
Q. Primary succession occurs on:
(a) Previously inhabited area
(b) Bare rock
(c) Cultivated land
(d) Forest soil
Ans: (b) Bare rock
Q. Secondary succession occurs where:
(a) No life existed before
(b) Soil is absent
(c) Life existed previously
(d) Water is absent
Ans: (c) Life existed previously
Q. Decomposition involves:
(a) Food production
(b) Breakdown of organic matter
(c) Respiration only
(d) Photosynthesis only
Ans: (b) Breakdown of organic matter
Q. Formation of humus is called:
(a) Mineralisation
(b) Leaching
(c) Humification
(d) Fragmentation
Ans: (c) Humification
Q. Release of inorganic nutrients is called:
(a) Humification
(b) Catabolism
(c) Mineralisation
(d) Fragmentation
Ans: (c) Mineralisation
Q. The main source of energy in ecosystem is:
(a) Moon
(b) Soil
(c) Sun
(d) Wind
Ans: (c) Sun
Q. Grazing food chain starts from:
(a) Detritus
(b) Carnivores
(c) Green plants
(d) Fungi
Ans: (c) Green plants
Q. Detritus food chain begins with:
(a) Producers
(b) Herbivores
(c) Dead organic matter
(d) Carnivores
Ans: (c) Dead organic matter
Q. Which of the following is not an abiotic component?
(a) Water
(b) Temperature
(c) Soil
(d) Bacteria
Ans: (d) Bacteria
Q. The pyramid of biomass may be inverted in:
(a) Forest ecosystem
(b) Grassland ecosystem
(c) Pond ecosystem
(d) Desert ecosystem
Ans: (c) Pond ecosystem
Q. Which organism occupies the highest trophic level?
(a) Producer
(b) Herbivore
(c) Top carnivore
(d) Decomposer
Ans: (c) Top carnivore
Q. Ecological pyramids were proposed by:
(a) Charles Elton
(b) Darwin
(c) Mendel
(d) Lamarck
Ans: (a) Charles Elton
Q. The process of breaking detritus into smaller particles is:
(a) Leaching
(b) Humification
(c) Fragmentation
(d) Mineralisation
Ans: (c) Fragmentation
Q. Which ecosystem has the highest productivity?
(a) Desert
(b) Pond
(c) Tropical rainforest
(d) Tundra
Ans: (c) Tropical rainforest
Q. The nutrient reservoir in ecosystem is called:
(a) Standing crop
(b) Standing state
(c) Food web
(d) Trophic level
Ans: (b) Standing state
Q. Energy flow in an ecosystem is:
(a) Cyclic
(b) One-way
(c) Reversible
(d) Random
Ans: (b) One-way
Q. Assertion (A): Energy flow in an ecosystem is unidirectional.
Reason (R): Energy lost as heat cannot be reused by organisms.
(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
Ans: (b) Both A and R are true, but R is not the correct explanation of A
Q. Assertion (A): Pyramid of energy is always upright.
Reason (R): Energy decreases at each successive trophic level.
(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
Ans: (d) A is false, but R is true
Q. Assertion (A): Decomposers help in nutrient recycling.
Reason (R): They break down dead organic matter into inorganic substances.
(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
Ans: (c) A is true, but R is false
Q. Assertion (A): Food webs increase stability of ecosystem.
Reason (R): Organisms have alternative food sources in food webs.
(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
Ans: (a) Both A and R are true and R is the correct explanation of A
Q. Assertion (A): Primary succession takes longer than secondary succession.
Reason (R): Soil is absent in primary succession.
(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
Ans: (b) Both A and R are true, but R is not the correct explanation of A
Q. Assertion (A): Humification forms humus in soil.
Reason (R): Humus is resistant to microbial action.
(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
Ans: (d) A is false, but R is true
Q. Assertion (A): Grazing food chain starts with producers.
Reason (R): Producers convert solar energy into chemical energy.
(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
Ans: (c) A is true, but R is false.
