🌸Chapter 12
Ecosystem
(4Marks)
Basics of Ecosystem
1.
Q: Explain the concept of an ecosystem
with examples.
A: An ecosystem is a functional unit of nature where living organisms
interact with each other and with non-living components to maintain a flow of
energy and cycling of nutrients.
Examples: Forest ecosystem, pond ecosystem, desert ecosystem.
2.
Q: Differentiate between natural and
artificial ecosystems with examples.
A:
- Natural ecosystems: Occur naturally; e.g.,
forests, ponds.
- Artificial ecosystems: Human-made; e.g., gardens,
aquariums.
3.
Q: Explain the role of producers in an
ecosystem.
A: Producers (autotrophs) synthesize their own food using sunlight
through photosynthesis. They form the base of the food chain and provide energy
for all consumers. Example: Grass, phytoplankton.
4.
Q: Explain the roles of consumers in
an ecosystem with examples.
A: Consumers depend on other organisms for food:
- Primary consumers: Herbivores (grasshopper, deer)
- Secondary consumers: Carnivores (frog, snake)
- Tertiary consumers: Top carnivores (hawk, tiger)
They transfer energy through trophic levels.
5.
Q: Explain the role of decomposers in
nutrient cycling.
A: Decomposers like fungi and bacteria break down dead matter into
simpler inorganic compounds, releasing nutrients like nitrogen, phosphorus, and
carbon back into the soil or water, maintaining ecosystem stability.
6.
Q: Differentiate between biotic and
abiotic components with examples.
A:
- Biotic: Living components like plants,
animals, microbes.
- Abiotic: Non-living factors like
sunlight, soil, temperature, and water.
Both interact to maintain ecosystem function.
7.
Q: Explain the interrelationship
between biotic and abiotic components with an example.
A: Abiotic factors like sunlight and water provide energy and habitat
for producers. Producers feed herbivores (biotic), which in turn feed
carnivores. Decomposers recycle nutrients to maintain soil fertility. Example:
Pond ecosystem.
8.
Q: Define habitat and niche. Explain
the difference.
A:
- Habitat: Place where an organism lives
(pond, forest).
- Niche: Role of an organism in the
ecosystem (what it eats, its interactions).
Difference: Habitat is address; niche is profession.
9.
Q: Explain the concept of ecological
balance.
A: Ecological balance is the stable state of an ecosystem where species
population and resources are maintained in equilibrium through interactions
among biotic and abiotic components.
10.
Q: What is an ecological pyramid?
Explain the types.
A: A diagram representing trophic levels:
- Pyramid of numbers: Shows number of organisms at
each level
- Pyramid of biomass: Shows total biomass at each
level
- Pyramid of energy: Shows energy content at each
level; always upright
Food Chain, Food Web, and Energy
Flow
11.
Q: Explain a food chain with an
example.
A: A food chain shows the linear flow of energy from one organism to
another.
Example: Grass → Grasshopper → Frog → Snake → Hawk.
12.
Q: Explain a food web with an example.
A: A food web is a network of interconnected food chains showing
multiple feeding relationships.
Example: Grass → Grasshopper → Frog → Snake → Hawk; Grass → Rabbit → Fox →
Hawk.
13.
Q: Explain the 10% law of energy
transfer with an example.
A: Only 10% of energy is transferred from one trophic level to the next;
90% is lost as heat.
Example: Grass captures 1000 kcal; Grasshopper gets 100 kcal; Frog gets 10
kcal.
14.
Q: Differentiate between a food chain
and a food web.
A:
- Food chain: Linear energy flow
- Food web: Network of interconnected food
chains
Food web shows complex interactions and stability.
15.
Q: Define trophic levels. Give
examples for each level.
A: Position of an organism in the food chain:
- Producer: Grass
- Primary consumer: Grasshopper
- Secondary consumer: Frog
- Tertiary consumer: Hawk
- Decomposers: Fungi
16.
Q: Explain why the pyramid of energy
is always upright.
A: Energy decreases at each trophic level due to metabolic activities
and heat loss. Hence, energy pyramids are upright in all ecosystems.
17.
Q: Explain inverted pyramid of numbers
with an example.
A: Few large producers support many herbivores.
Example: One tree (producer) supports thousands of insects (primary consumers).
18.
Q: Explain inverted pyramid of biomass
with an example.
A: In aquatic ecosystems, biomass of producers (phytoplankton) is lower
than primary consumers (zooplankton).
19.
Q: Explain the flow of energy in an
ecosystem.
A: Energy flows from sun → producers → consumers → decomposers → lost as
heat. It is unidirectional.
20.
Q: What is NPP? Explain its
significance.
A: Net Primary Productivity is the energy available to consumers after
respiration by producers. It determines the carrying capacity and energy flow
in an ecosystem.
Ecological Succession
21.
Q: Define ecological succession.
Explain its types.
A: Succession is the gradual, predictable change in species composition
over time.
- Primary succession: No soil initially (bare rock →
climax)
- Secondary succession: Soil present after disturbance
(abandoned farmland → climax)
22.
Q: Explain the stages of primary
succession.
A: Pioneer species (lichens) → Mosses → Grasses → Shrubs → Trees →
Climax community.
23.
Q: Explain secondary succession with
an example.
A: Occurs on previously vegetated land after disturbance.
Example: Abandoned farmland → grass → shrubs → trees.
24.
Q: Define climax community. Explain
its importance.
A: Stable, mature community at the end of succession.
Importance: Maintains ecological balance, stable nutrient cycling,
biodiversity.
25.
Q: What are pioneer species? Give
examples.
A: First species to colonize barren habitats; help soil formation.
Examples: Lichens, mosses.
26.
Q: Explain the terms sere and seral
community.
A:
- Sere: Stage of succession
- Seral community: Transitional community between
pioneer and climax
27.
Q: Explain factors controlling
succession.
A: Abiotic factors: climate, soil, light, water.
Biotic factors: competition, predation, mutualism.
28.
Q: Explain the role of microorganisms
in succession.
A: Microorganisms decompose organic matter, enrich soil nutrients, and
facilitate colonization of plants.
29.
Q: Give an example of primary and
secondary succession.
A:
- Primary: Lichen on bare rock →
climax forest
- Secondary: Abandoned farmland →
grass → shrubs → trees
30.
Q: Why is succession important for
ecosystems?
A: It restores degraded land, increases biodiversity, maintains
ecosystem stability, and improves productivity.
Biogeochemical Cycles
31.
Q: Explain the nitrogen cycle.
A: Nitrogen cycle includes:
- Nitrogen fixation: N₂ → NH₃ (Rhizobium)
- Nitrification: NH₃ → NO₂⁻ → NO₃⁻
- Assimilation: Plants absorb nitrates
- Ammonification: Organic N → NH₃
- Denitrification: NO₃⁻ → N₂
32.
Q: Explain the phosphorus cycle.
A: Phosphorus moves from rocks → soil → plants → animals → decomposers →
soil → rock (weathering). No gaseous phase.
33.
Q: Explain the carbon cycle.
A: Carbon moves from atmosphere CO₂ → plants (photosynthesis) → animals
→ decomposers → atmosphere (respiration, combustion).
34.
Q: Explain the hydrological cycle.
A: Water circulates via evaporation → condensation → precipitation →
runoff → groundwater. Maintains water availability in ecosystems.
35.
Q: Explain the role of decomposers in
nutrient cycling.
A: Decomposers break down dead matter, release nutrients like N, P, C,
and maintain soil fertility and ecosystem balance.
36.
Q: Explain human impact on the carbon
and nitrogen cycles.
A: Deforestation, fossil fuel burning → ↑ CO₂ → global warming.
Excess fertilizer use → nitrogen leaching → eutrophication.
37.
Q: Explain eutrophication and its
effects.
A: Excess nutrient input (N, P) in water → algal bloom → oxygen depletion
→ death of aquatic animals.
38.
Q: Explain biological magnification.
A: Accumulation of persistent toxins (e.g., DDT, Hg) at higher trophic
levels in food chains, harming top predators.
39.
Q: Explain acid rain and its
ecological effects.
A: SO₂ and NO₂ react with rain → H₂SO₄, HNO₃ → acid rain → damages
plants, aquatic life, and soil fertility.
40.
Q: Explain global warming and its
effect on ecosystems.
A: Greenhouse gases trap heat → temperature rise → melting glaciers, sea
level rise, loss of biodiversity, and altered ecosystem balance.
Ecosystem Types and Conservation
41.
Q: Explain the characteristics of
forest ecosystems.
A: High biodiversity, multi-layered canopy, high productivity, rich
soil, complex food webs.
42.
Q: Explain the characteristics of
grassland ecosystems.
A: Dominated by grasses, moderate rainfall, moderate productivity,
supports herbivores like bison and carnivores like lions.
43.
Q: Explain the characteristics of
desert ecosystems.
A: Arid, low vegetation, xerophytes, low productivity, extreme temperatures.
44.
Q: Explain the characteristics of
aquatic ecosystems.
A: Include freshwater (pond, lake) and marine (ocean, estuary),
producers are phytoplankton, decomposers recycle nutrients, energy flow is
unidirectional.
45.
Q: Explain the concept of biodiversity
hotspots.
A: Regions with high species richness and endemism; important for
conservation. Examples: Himalayas, Western Ghats, Indo-Burma.
46.
Q: Explain the role of protected areas
in conservation.
A: National parks, wildlife sanctuaries, biosphere reserves conserve
species, maintain ecological balance, and allow sustainable human use in buffer
zones.
47.
Q: Explain the concept of edge species
(EDGE).
A: Species that are Evolutionarily Distinct and Globally Endangered;
crucial for maintaining ecosystem diversity.
48.
Q: Explain bioremediation with an
example.
A: Use of microorganisms to clean pollutants.
Example: Bacteria degrading oil spills, fungi degrading pesticides.
49.
Q: Explain CITES and its importance.
A: Convention on International Trade in Endangered Species regulates
trade of threatened species to prevent extinction.
50.
Q: Explain REDD program in forest
conservation.
A: REDD (Reducing Emissions from Deforestation and Forest Degradation)
aims to reduce CO₂ emissions by conserving forests and promoting sustainable
forest management.
