Environment Studies
Unit 3: MCQ Practice — structure and function, energy flow, food chains, pyramids and succession
25 MCQs with Answers & Explanations (English + Hinglish) • BA • Semester 1 (AEC)
- Q1: The term “ecosystem” was coined by:
- Q2: In an ecosystem, green plants are called:
- Q3: Decomposers in an ecosystem are mainly:
- Q4: The 10 percent law of energy transfer was proposed by:
- Q5: Which of the following is a correct food chain?
- Q6: A food web is best described as:
- Q7: Herbivores occupy which trophic level?
- Q8: The pyramid of energy in any ecosystem is:
- Q9: In the ocean, the pyramid of biomass is:
- Q10: Ecological succession means:
- Q11: The pioneer organisms on bare rock in primary succession are:
- Q12: A climax community is:
- Q13: Primary succession begins:
- Q14: Secondary succession is faster than primary because:
- Q15: In a pond ecosystem, the producers are:
- Q16: Xerarch succession begins in:
- Q17: Hydrarch succession begins in:
- Q18: Food chains are usually short (4–5 levels) because:
- Q19: A detritus food chain begins with:
- Q20: The transition zone between two ecosystems is called the:
- Q21: Mangrove forests in India are best seen at:
- Q22: Which of the following is a <strong>natural</strong> ecosyst…
- Q23: Which of the following is an <strong>artificial</strong> eco…
- Q24: Energy flow through an ecosystem is:
- Q25: Nutrients like carbon, nitrogen and phosphorus in an ecosyst…
Q1 The term “ecosystem” was coined by: 1 mark
- AA. G. Tansley, 1935 ✓ Correct
- BErnst Haeckel, 1866
- CCharles Darwin, 1859
- DE. P. Odum, 1953
British ecologist A. G. Tansley ne 1935 me nature ki functional unit ke liye 'ecosystem' coin kiya.
Q2 In an ecosystem, green plants are called: 1 mark
- AConsumers
- BScavengers
- CDecomposers
- DProducers ✓ Correct
Producers (green plants) photosynthesis se food banate hain, solar energy capture karte hain.
Q3 Decomposers in an ecosystem are mainly: 1 mark
- ABacteria and fungi ✓ Correct
- BLions and tigers
- CDeer and rabbits
- DEagles and hawks
Bacteria aur fungi dead matter todte hain, nutrients soil ko wapas dete hain.
Q4 The 10 percent law of energy transfer was proposed by: 1 mark
- AErnst Haeckel, 1866
- BA. G. Tansley, 1935
- CRaymond Lindeman, 1942 ✓ Correct
- DCharles Elton, 1927
Lindeman (1942): next trophic level me sirf ~10% energy jaati hai; ~90% heat me lost.
Q5 Which of the following is a correct food chain? 1 mark
- ASnake → grass → hawk → frog
- BFrog → grass → snake → hawk
- CHawk → snake → frog → grasshopper → grass
- DGrass → grasshopper → frog → snake → hawk ✓ Correct
Food chains producers se upar chalte hain: plant → herbivore → small carnivore → large carnivore.
Q6 A food web is best described as: 1 mark
- AA fishing net
- BA spider's net
- CA single linear food chain
- DA network of interconnected food chains ✓ Correct
Nature me zyadaatar organisms kai species khaate hain, isliye chains interconnect hoke web banati hain.
Q7 Herbivores occupy which trophic level? 1 mark
- ASecond (primary consumers) ✓ Correct
- BFourth (tertiary consumers)
- CThird (secondary consumers)
- DFirst (producers)
Producers level 1 hain; unhe khaane wale herbivores level 2 pe primary consumers hain.
Q8 The pyramid of energy in any ecosystem is: 1 mark
- ASometimes upright
- BNever formed
- CAlways inverted
- DAlways upright ✓ Correct
Kyunki har transfer pe energy lost hoti hai (10% law), energy kabhi upar increase nahi ho sakti.
Q9 In the ocean, the pyramid of biomass is: 1 mark
- ALinear
- BUpright
- CAbsent
- DInverted ✓ Correct
Tiny, short-lived phytoplankton (small biomass) large fish support karte hain — inverted pyramid.
Q10 Ecological succession means: 1 mark
- ASudden extinction of species
- BHibernation of animals
- CGradual change in species composition of an area over time ✓ Correct
- DSeasonal migration of birds
Succession simple pioneer communities se stable climax community ki taraf move karti hai.
Q11 The pioneer organisms on bare rock in primary succession are: 1 mark
- AElephants
- BMango trees
- CLichens and mosses ✓ Correct
- DFish
Lichens acids secrete karte hain jo rock ko slowly soil me todte hain later plants ke liye.
Q12 A climax community is: 1 mark
- AAn unstable community
- BThe first stage of succession
- CThe final, stable stage of succession ✓ Correct
- DA temporary stage
Example: climate ke saath balance me ek mature forest, disturb hone tak lasting.
Q13 Primary succession begins: 1 mark
- AIn deep oceans
- BOn a lifeless surface with no soil ✓ Correct
- COn fertile farm soil
- DInside cities
Ye bare rock, new lava ya glacial retreat pe start hoti hai — zero se soil banana centuries leta hai.
Q14 Secondary succession is faster than primary because: 1 mark
- ASoil already exists from the earlier community ✓ Correct
- BThere are no plants
- CThere is less sunlight
- DThere is more rainfall
Disturbed land (burnt forest, abandoned field) pe seeds aur roots survive karte hain, regrowth quick hota hai.
Q15 In a pond ecosystem, the producers are: 1 mark
- AHerons
- BPhytoplankton, algae and rooted plants ✓ Correct
- CFrogs
- DSmall fish
Microscopic phytoplankton aur algae plus lotus jaise plants ponds me sunlight capture karte hain.
Q16 Xerarch succession begins in: 1 mark
- ADry, water-scarce areas ✓ Correct
- BSnow-covered peaks
- CSaline lagoons
- DWet marshy areas
Xero = dry: dry bare rock ya sand pe start hoke forest tak succession.
Q17 Hydrarch succession begins in: 1 mark
- ABare rock
- BIce sheets
- COpen water bodies ✓ Correct
- DDeserts
Hydr = water: ponds/lakes me succession jab wo slowly fill hoke land bante hain.
Q18 Food chains are usually short (4–5 levels) because: 1 mark
- AEnergy is lost at each transfer (10% law) ✓ Correct
- BHumans cut them short
- CToo much energy is available
- DThere are few species on earth
Sirf ~10% pass hone se 4–5 trophic levels ke beyond little energy bachti hai.
Q19 A detritus food chain begins with: 1 mark
- ADead organic matter ✓ Correct
- BGreen plants
- CSunlight
- DFresh water
Ye dead leaves/litter → decomposers → small animals se start hoti hai, grazing chains ke unlike.
Q20 The transition zone between two ecosystems is called the: 1 mark
- AEcotone ✓ Correct
- BHabitat
- CBiome
- DNiche
Ecotones (e.g. forest–grassland edge) me often dono sides ki species hoti hain — edge effect.
Q21 Mangrove forests in India are best seen at: 1 mark
- AThar Desert
- BLadakh
- CSundarbans (coastal West Bengal) ✓ Correct
- DWestern Ghats peaks
Mangroves salty coastal mud me grow karte hain; Sundarbans duniya ka largest mangrove forest hai.
Q22 Which of the following is a natural ecosystem? 1 mark
- ACity garden
- BAquarium
- CCrop field
- DForest ✓ Correct
Forests human management ke bina chalte hain; aquaria, crop fields, gardens man-made hain.
Q23 Which of the following is an artificial ecosystem? 1 mark
- ACrop field ✓ Correct
- BTundra
- CDesert
- DOcean
Crop fields humans dwara chosen species aur inputs ke saath create aur maintain kiye jaate hain.
Q24 Energy flow through an ecosystem is: 1 mark
- AReversible
- BRandom
- COne-way (unidirectional) ✓ Correct
- DCyclic
Solar energy producers → consumers → decomposers flow karti hai aur heat me lost hoti hai; kabhi wapas cycle nahi karti.
Q25 Nutrients like carbon, nitrogen and phosphorus in an ecosystem: 1 mark
- ACycle repeatedly between living and non-living parts ✓ Correct
- BDisappear forever
- CFlow one-way like energy
- DAre destroyed by decomposers
Energy ke unlike, materials recycled hote hain: decomposers unhe soil ko wapas dete hain plants ke reuse ke liye.