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1. Interdependence of Organisms
- All organisms depend on each other and their environment to survive. This relationship is called interdependence.
- Ecosystem: A community of living organisms interacting with each other and their non-living environment.
- Biotic Factors: Living components (e.g., plants, animals, bacteria).
- Abiotic Factors: Non-living components (e.g., sunlight, water, soil, temperature).
2. Energy Flow in an Ecosystem
- Energy Source: The Sun is the primary source of energy for most ecosystems.
- Producers (Autotrophs):
- Organisms like plants and algae that produce their own food through photosynthesis.
- Convert solar energy into chemical energy (glucose).
- Consumers (Heterotrophs):
- Organisms that eat other organisms to obtain energy.
- Classified into:
- Primary Consumers: Herbivores that eat plants (e.g., rabbits, caterpillars).
- Secondary Consumers: Carnivores that eat herbivores (e.g., foxes, frogs).
- Tertiary Consumers: Top predators that eat secondary consumers (e.g., hawks, lions).
- Decomposers:
- Organisms like fungi and bacteria that break down dead material, returning nutrients to the soil.
3. Food Chains and Food Webs
- Food Chain:
- A linear sequence showing how energy flows through an ecosystem.
- Example: Grass → Rabbit → Fox.
- Food Web:
- A network of interconnected food chains, showing how organisms have multiple feeding relationships.
- More realistic than a food chain.
4. Energy Loss
- Energy is lost at each trophic level:
- Only about 10% of the energy is transferred to the next level.
- Most energy is lost as heat or used for life processes (e.g., movement, reproduction).
- This limits the number of trophic levels in an ecosystem.
5. Cycles of Matter
- Matter (e.g., water, carbon, nitrogen) cycles through ecosystems, ensuring resources are reused.
- Evaporation: Water from oceans, lakes, and rivers turns into vapour.
- Condensation: Water vapour cools and forms clouds.
- Precipitation: Water falls as rain, snow, or sleet.
- Collection: Water returns to oceans, rivers, or underground reservoirs.
- Carbon moves between the atmosphere, organisms, and Earth.
- Photosynthesis: Plants absorb CO₂ and convert it into glucose.
- Respiration: Organisms release CO₂ back into the atmosphere.
- Decomposition: Decomposers break down dead organisms, releasing CO₂.
- Combustion: Burning fossil fuels releases stored carbon into the atmosphere.
- Nitrogen is essential for proteins and DNA in organisms.
- Nitrogen Fixation: Bacteria convert nitrogen gas (N₂) into forms plants can absorb.
- Assimilation: Plants take up nitrogen compounds through their roots.
- Decomposition: Dead organisms and waste return nitrogen to the soil.
- Denitrification: Bacteria convert nitrogen compounds back to N₂ gas.
6. Examples of Interdependence
- Pollination: Bees depend on flowers for nectar, and flowers depend on bees to spread pollen.
- Predator-Prey Relationships: Wolves control deer populations, preventing overgrazing.
- Symbiosis:
- Mutualism: Both species benefit (e.g., clownfish and sea anemones).
- Commensalism: One species benefits, the other is unaffected (e.g., barnacles on whales).
- Parasitism: One species benefits at the expense of the other (e.g., fleas on dogs).
7. Importance of Biodiversity
- Biodiversity ensures the stability of ecosystems by:
- Supporting food webs.
- Providing resources like food, medicine, and materials.
- Helping ecosystems recover from disturbances (e.g., natural disasters).
Summary
- Organisms rely on each other and their environment in complex relationships.
- Energy flows through ecosystems via food chains and webs, with energy loss at each level.
- Matter cycles (e.g., water, carbon, nitrogen) ensure the availability of essential elements.
- Biodiversity and interdependence are critical for ecosystem stability and resilience.
Questions:
Q1: What is an ecosystem?
A: An ecosystem is a community of living organisms interacting with each other and their non-living environment.
Q2: What is interdependence in an ecosystem?
A: Interdependence refers to how organisms in an ecosystem rely on each other and their environment for survival.
Q3: What is the primary source of energy for most ecosystems?
A: The Sun is the primary source of energy.
Q4: What are producers in an ecosystem?
A: Producers are organisms, like plants and algae, that make their own food through photosynthesis.
Q5: What are the three types of consumers in a food chain?
A:
A: Decomposers, like fungi and bacteria, break down dead material and return nutrients to the soil.
Q7: What is the difference between a food chain and a food web?
A:
A: Most energy is lost as heat or used for life processes, with only about 10% passed to the next level.
Q9: Name the three main cycles of matter in an ecosystem.
A: The water cycle, carbon cycle, and nitrogen cycle.
Q10: How does the water cycle work?
A:
A: Plants absorb carbon dioxide (CO₂) and convert it into glucose, reducing atmospheric CO₂ levels.
Q12: How do humans impact the nitrogen cycle?
A: Overuse of fertilisers adds excess nitrogen to the soil, which can lead to water pollution and affect ecosystems.
Q13: What is biodiversity, and why is it important?
A: Biodiversity is the variety of life in an ecosystem. It helps maintain stability, provides resources, and supports recovery from disturbances.
Q14: Give an example of interdependence in an ecosystem.
A: Bees depend on flowers for nectar, and flowers depend on bees for pollination.
Q15: What is mutualism?
A: Mutualism is a relationship where both species benefit, like clownfish living in sea anemones.
A: An ecosystem is a community of living organisms interacting with each other and their non-living environment.
Q2: What is interdependence in an ecosystem?
A: Interdependence refers to how organisms in an ecosystem rely on each other and their environment for survival.
Q3: What is the primary source of energy for most ecosystems?
A: The Sun is the primary source of energy.
Q4: What are producers in an ecosystem?
A: Producers are organisms, like plants and algae, that make their own food through photosynthesis.
Q5: What are the three types of consumers in a food chain?
A:
- Primary consumers: Herbivores that eat plants.
- Secondary consumers: Carnivores that eat herbivores.
- Tertiary consumers: Top predators that eat secondary consumers.
A: Decomposers, like fungi and bacteria, break down dead material and return nutrients to the soil.
Q7: What is the difference between a food chain and a food web?
A:
- A food chain shows a linear flow of energy through an ecosystem.
- A food web is a network of interconnected food chains, showing multiple feeding relationships.
A: Most energy is lost as heat or used for life processes, with only about 10% passed to the next level.
Q9: Name the three main cycles of matter in an ecosystem.
A: The water cycle, carbon cycle, and nitrogen cycle.
Q10: How does the water cycle work?
A:
- Evaporation: Water turns into vapour.
- Condensation: Vapour cools and forms clouds.
- Precipitation: Water falls as rain, snow, or sleet.
- Collection: Water returns to rivers, oceans, or underground.
A: Plants absorb carbon dioxide (CO₂) and convert it into glucose, reducing atmospheric CO₂ levels.
Q12: How do humans impact the nitrogen cycle?
A: Overuse of fertilisers adds excess nitrogen to the soil, which can lead to water pollution and affect ecosystems.
Q13: What is biodiversity, and why is it important?
A: Biodiversity is the variety of life in an ecosystem. It helps maintain stability, provides resources, and supports recovery from disturbances.
Q14: Give an example of interdependence in an ecosystem.
A: Bees depend on flowers for nectar, and flowers depend on bees for pollination.
Q15: What is mutualism?
A: Mutualism is a relationship where both species benefit, like clownfish living in sea anemones.
