🌸Chapter 12
Ecosystem
(2Marks)
Basics of Ecosystem
1.
Q: Who coined the term “ecosystem”?
A: A.G. Tansley in 1935.
2.
Q: Define ecosystem.
A: An ecosystem is a functional unit of nature where biotic and abiotic
components interact with each other.
3.
Q: Give two examples of natural ecosystems.
A: Forests and ponds.
4.
Q: Give two examples of artificial
ecosystems.
A: Gardens and aquariums.
5.
Q: Name the two main components of an
ecosystem.
A: Biotic (living) and abiotic (non-living) components.
6.
Q: What are biotic components?
A: All living organisms in an ecosystem, e.g., plants, animals,
microbes.
7.
Q: What are abiotic components?
A: Non-living physical and chemical factors, e.g., sunlight, water,
temperature, soil.
8.
Q: Define producers.
A: Organisms that synthesize their own food through photosynthesis,
e.g., plants.
9.
Q: Define consumers.
A: Organisms that depend on other organisms for food, e.g., herbivores,
carnivores, omnivores.
10.
Q: Define decomposers.
A: Organisms that break down dead matter and recycle nutrients, e.g.,
bacteria and fungi.
Food Chain, Food Web, and Trophic
Levels
11.
Q: What is a food chain?
A: A linear sequence of organisms through which energy flows in an
ecosystem.
12.
Q: What is a food web?
A: A network of interconnected food chains showing complex feeding
relationships.
13.
Q: Name the first trophic level.
A: Producers (autotrophs).
14.
Q: Name the second trophic level.
A: Primary consumers (herbivores).
15.
Q: What are secondary consumers?
A: Carnivores that feed on herbivores.
16.
Q: What is an omnivore?
A: An organism that eats both plants and animals.
17.
Q: Give one example of a decomposer.
A: Bacteria or fungi.
18.
Q: What is the 10% law of energy
transfer?
A: Only 10% of energy is transferred to the next trophic level; 90% is
lost as heat.
19.
Q: Which pyramid is always upright?
A: Pyramid of energy.
20.
Q: Give an example of an inverted
pyramid of numbers.
A: Tree ecosystem (few large producers support many herbivores).
Productivity & Energy Flow
21.
Q: Define Gross Primary Productivity
(GPP).
A: Total energy captured by producers through photosynthesis per unit
area per unit time.
22.
Q: Define Net Primary Productivity
(NPP).
A: Energy available to consumers after respiration by producers; NPP =
GPP – Respiration.
23.
Q: What is secondary productivity?
A: Rate of production of biomass by consumers (herbivores and
carnivores).
24.
Q: Name two factors affecting primary
productivity.
A: Light intensity and nutrient availability.
25.
Q: Which ecosystem has the highest
NPP?
A: Tropical rainforest.
26.
Q: Which ecosystem has the lowest NPP?
A: Desert.
27.
Q: What is the fate of energy in an
ecosystem?
A: Energy flows one-way from producers → consumers → decomposers and is
lost as heat.
28.
Q: Define energy flow in an ecosystem.
A: The transfer of energy from one trophic level to the next in a linear
manner.
29.
Q: Name the primary energy source for
all ecosystems.
A: Sunlight.
30.
Q: Why are energy pyramids upright?
A: Energy decreases at each trophic level due to loss as heat and
metabolism.
Ecological Succession
31.
Q: Define ecological succession.
A: The gradual, predictable, and directional change in the species
composition of a community over time.
32.
Q: What is primary succession?
A: Succession on bare rock or lifeless areas where soil is initially
absent.
33.
Q: What is secondary succession?
A: Succession in areas where soil is present but vegetation has been
disturbed.
34.
Q: Name pioneer species in primary
succession.
A: Lichens and mosses.
35.
Q: Define climax community.
A: A stable, mature community at the final stage of succession.
36.
Q: Give an example of secondary
succession.
A: Abandoned farmland → grass → shrubs → trees.
37.
Q: Give the correct sequence in
primary succession.
A: Lichen → Moss → Grass → Shrubs → Trees.
38.
Q: Which factor controls succession?
A: Abiotic factors such as climate, soil, and light availability.
39.
Q: What is a sere?
A: A stage or series of stages in ecological succession.
40.
Q: What is seral community?
A: Transitional communities that appear during succession before climax.
Biogeochemical Cycles
41.
Q: Name the process that converts
atmospheric nitrogen to ammonia.
A: Nitrogen fixation.
42.
Q: Name a nitrogen-fixing bacteria.
A: Rhizobium.
43.
Q: Which nutrient cycle does not
involve the atmosphere?
A: Phosphorus cycle.
44.
Q: What is ammonification?
A: Conversion of organic nitrogen from dead organisms into ammonia by
decomposers.
45.
Q: What is denitrification?
A: Conversion of nitrates (NO₃⁻) into nitrogen gas (N₂) by denitrifying
bacteria.
46.
Q: What is the largest carbon
reservoir?
A: Oceans.
47.
Q: Define the hydrological cycle.
A: Continuous circulation of water through evaporation, condensation,
precipitation, and runoff.
48.
Q: Give one human activity that
affects the carbon cycle.
A: Deforestation or burning of fossil fuels.
49.
Q: What is the role of decomposers in
nutrient cycles?
A: They recycle nutrients from dead organisms back to the ecosystem.
50.
Q: Give one example of a biogeochemical
cycle that is essential for plant growth.
A: Nitrogen cycle or phosphorus cycle.
