Ch.7: Energy Flow in an Ecosystem
- Arrowmite
- Jun 25
- 15 min read
Updated: Jul 4
Energy Flow in an Ecosystem | Class 9 | Science | Chaptert 7 | Maharashtra State Board
Explore the energy flow in an ecosystem through food chains and food webs. It covers the concepts of trophic levels and the energy pyramid, showing how energy and matter move through various organisms. The chapter also discusses important bio-geo-chemical cycles like the carbon, oxygen, and nitrogen cycles. Simple examples and diagrams help students understand the balance of nature.
Questions & Answers
1. Complete the following table
(Carefully study the carbon, oxygen and nitrogen cycles).
Ans.
Bio-geo-chemical cycles | Biotic processes | Abiotic processes |
1. Carbon cycle | Photosynthesis, respiration in plants and animals, decomposition of organisms | Burning of fossil fuels, volcanic eruptions, forest fires, diffusion of CO₂ in water |
2. Oxygen cycle | Photosynthesis, respiration by living organisms, decomposition | Combustion, rusting (oxidation), ozone formation, oxidation reactions in the atmosphere |
3. Nitrogen cycle | Nitrogen fixation by bacteria, decomposition (ammonification), nitrification | Lightning (atmospheric nitrogen fixation), industrial processes, denitrification |
2. Correct and rewrite the following statements and justify your corrections.
a. Carnivores occupy the second trophic level in the food chain.
Ans.
Incorrect Statement.
Corrected Statement:
Carnivores occupy the third or higher trophic levels in the food chain.
Justification:
The second trophic level is occupied by herbivores (primary consumers), which feed on producers (plants). Carnivores feed on herbivores, so they belong to the third (secondary consumers) or higher levels.
b. The flow of nutrients in an ecosystem is considered to be a ‘one-way’ transport.
Ans.
Incorrect Statement.
Corrected Statement:
The flow of nutrients in an ecosystem is cyclic, not one way.
Justification:
Nutrients are constantly recycled between biotic (living) and abiotic (non-living) components through biogeochemical cycles like the carbon, nitrogen, and oxygen cycles.
c. Plants in an ecosystem are called primary consumers.
Ans.
Incorrect Statement.
Corrected Statement:
Plants in an ecosystem are called producers.
Justification:
Plants produce food through photosynthesis and are at the base of the food chain. Primary consumers are herbivores that feed on plants.
3. Give reasons.
a. Energy flow through an ecosystem is ‘one way’.
Ans.
Energy enters the ecosystem through sunlight, which is captured by plants during photosynthesis. This energy then passes from producers to herbivores, carnivores, and finally to decomposers. At each step, some energy is lost as heat and cannot be reused, so it does not return to the source. Hence, energy flow is one way.
b. Equilibrium is necessary in the various bio-geo-chemical cycles.
Ans.
Bio-geo-chemical cycles maintain the balance of essential elements like carbon, oxygen, and nitrogen. If this equilibrium is disturbed (e.g., excess carbon dioxide), it can lead to climate change, pollution, and imbalance in ecosystems. Therefore, maintaining balance ensures the health and sustainability of the ecosystem.
c. Flow of nutrients through an ecosystem is cyclic.
Ans.
Nutrients like carbon, oxygen, and nitrogen are recycled through the ecosystem. They move from abiotic components (air, water, soil) to living organisms and back through processes like respiration, decomposition, and nitrogen fixation. This recycling keeps nutrients available for all living beings, making the flow cyclic.
4. Explain the following cycles in your own words with suitable diagrams.
a. Carbon cycle.
Ans.
The carbon cycle is the continuous movement of carbon among the atmosphere, living organisms, water, and the earth.
Plants absorb CO₂ from the air during photosynthesis and convert it into food.
Animals eat plants and use that carbon for energy.
Through respiration, decomposition, and combustion (burning of fossil fuels), carbon returns to the atmosphere as CO₂.
Decomposers break down dead bodies and release carbon back into soil and air.
(Draw diagram):
Atmosphere → Plants → Animals → Decomposers → Atmosphere(Include arrows for respiration, decomposition, fossil fuel burning, etc.)
b. Nitrogen cycle.
Ans.
The nitrogen cycle describes how nitrogen is converted into different forms and used by living organisms.
Nitrogen fixation: Bacteria in soil or roots convert nitrogen gas (N₂) into nitrates.
Plants absorb nitrates to make proteins.
Animals eat plants and get nitrogen.
When plants and animals die, decomposition releases ammonia.
Nitrification: Ammonia is converted to nitrates again.
Denitrification: Some bacteria convert nitrates back into nitrogen gas, releasing it into the atmosphere.
(Draw Diagram)
Atmosphere (N₂) → Nitrogen-fixing bacteria → Plants → Animals → Decomposers → Soil → Denitrifying bacteria → Atmosphere
c. Oxygen cycle.
Ans.
The oxygen cycle is the movement of oxygen within the atmosphere, biosphere, and lithosphere.
Plants release oxygen during photosynthesis.
Animals and humans use oxygen for respiration, which produces CO₂.
Decomposition, combustion, and rusting also consume oxygen.
Oxygen is continuously used and replenished to maintain balance.
(Draw Diagram)
Photosynthesis (O₂ release) → Respiration (O₂ use) → Combustion, Rusting → Plants again release O₂
5. What would you do to help maintain the equilibrium in the various bio-geochemical cycles? Explain in brief.
Ans.
To help maintain the equilibrium in the bio-geo-chemical cycles, I would:
Plant more trees – Trees absorb carbon dioxide and release oxygen, helping balance the carbon and oxygen cycles.
Avoid burning waste and fossil fuels – Reduces air pollution and prevents excessive carbon dioxide release.
Use organic fertilizers – Supports natural nitrogen fixation and reduces chemical pollution.
Save water and avoid wastage – Maintains the water cycle and aquatic balance.
Promote waste segregation and composting – Helps in nutrient recycling through decomposition.
These actions support the natural recycling of nutrients and maintain balance in ecosystems.
6. Explain in detail the inter-relationship between the food chain and food web.
Ans.
A food chain is a linear sequence that shows how energy and nutrients flow from one organism to another in an ecosystem. It begins with producers (plants) and moves up through herbivores, carnivores, and finally top consumers.
Example:
Grass → Grasshopper → Frog → Snake → Eagle
A food web, on the other hand, is a network of interconnected food chains. It shows how different organisms are linked by various feeding relationships. Since most animals eat and are eaten by more than one kind of organism, a food web gives a more realistic picture of energy flow in nature.
Inter-relationship:
Many food chains combine to form a food web.
If one organism is removed from a food chain, it can affect the entire food web.
Food webs provide stability to ecosystems because organisms have alternative food sources.
Both food chains and food webs show energy transfer between trophic levels.
Conclusion:
The food chain is a simple part of the food web. Both are essential to understand the feeding relationships and energy flow in an ecosystem.
7. State the different types of bio-geochemical cycles and explain the importance of those cycles.Types of Bio-geo-chemical Cycles:
Ans.
Gaseous Cycles
These cycles involve nutrients found in the atmosphere.
Examples: Carbon cycle, Oxygen cycle, Nitrogen cycle, Water cycle.
Sedimentary Cycles
These cycles involve nutrients found in soil, sediments, and rocks.
Examples: Phosphorus cycle, Sulphur cycle, Calcium cycle.
Importance of Bio-geo-chemical Cycles:
Recycling of Nutrients:These cycles return essential elements like carbon, nitrogen, and oxygen to the environment, which are reused by living organisms.
Maintain Ecological Balance: They help maintain the balance between the biotic (living) and abiotic (non-living) components of ecosystems.
Support Life Processes: Nutrients from these cycles are needed for photosynthesis, respiration, protein synthesis, and DNA formation.
Regulate Climate: The carbon cycle and water cycle help regulate Earth’s temperature and weather patterns.
Prevent Resource Depletion: Continuous cycling ensures that natural resources are not exhausted and remain available for future generations.
Conclusion:
Bio-geo-chemical cycles are essential for sustaining life on Earth by continuously recycling nutrients and maintaining the balance of nature.
8. Explain the following with suitable examples.
a. What type of changes occur in the amount of energy during its transfer from plants to apex consumers?
Ans.
As energy flows from plants (producers) to herbivores, then to carnivores, and finally to apex consumers, the amount of energy decreases at each level.
This happens because only 10% of the energy is transferred to the next trophic level.
The rest is lost as heat during metabolic activities like respiration, movement, digestion, etc.
Example:
If plants capture 10,000 kcal of energy from the sun → herbivores get only 1,000 kcal → carnivores get 100 kcal → apex consumers get just 10 kcal.
Conclusion:
Energy decreases as it moves up the food chain.
b. What are the differences between flow of matter and of energy in an ecosystem? Why?
Ans.
Aspect | Flow of Matter | Flow of Energy |
Direction | Cyclic – it is recycled in the ecosystem. | One-way – it moves from sun to producers to consumers and is lost as heat. |
Example | Water, nitrogen, carbon cycles. | Solar energy captured by plants and passed on. |
Reason | Decomposers return matter to nature. | Energy is used or lost and cannot return to the sun. |
Conclusion:
Matter cycles within the ecosystem through bio-geo-chemical cycles, while energy flows in one direction and cannot be reused.
E X T R A
Intext Questions and Answers
1. Can you Recall?
1. What is meant by nitrogen fixation?
Ans.
Nitrogen fixation is the process of converting nitrogen gas (N₂) from the atmosphere into usable compounds like nitrates or ammonia, which can be absorbed by plants for growth.
2. Which microbes bring about the process of nitrogen fixation?
Ans.
Nitrogen-fixing bacteria like Rhizobium, Azotobacter, and Clostridium help in nitrogen fixation. Rhizobium lives in root nodules of leguminous plants.
3. What is meant by ‘ecosystem’?
Ans.
An ecosystem is a community of living organisms (biotic) interacting with non-living (abiotic) components like air, water, soil, and sunlight in a specific area.
4. Which are different types of ecosystems?
Ans.
Ecosystems can be of two main types:
Natural ecosystems (e.g., forest, desert, ocean, lake)
Artificial ecosystems (e.g., gardens, aquariums, crop fields)
5. How do interactions take place between biotic and abiotic factors of an ecosystem?
Ans.
Biotic factors (plants, animals, microbes) depend on abiotic factors (sunlight, air, water, soil) for survival, growth, and reproduction. For example, plants use sunlight, water, and CO₂ to make food; animals eat plants; decomposers recycle nutrients back into the soil.
2. Choose and write the correct option:
1. An intricate network of food chains is called
(a) Biosphere
(b) Food web
(c) Energy pyramid
(d) Ecosystem
Ans.(b) food web
2. Fungi and other microbes are called
(a) Producers
(b) Consumers
(c) Decomposers
(d) Omnivores
Ans.
(c) decomposers
3. Oxygen forms of the atmosphere.
(a) 78%
(b) 21%
(c) 10%
(d) 90%
Ans.
(b) 21%
4. Microbes which do not need oxygen are called
(a) Producers
(b) Aerobes
(c) Anaerobes
(d) Decomposers
Ans.
(c) anaerobes
5. The pattern of energy exchange in an ecosystem is called a
(a) Food chain
(b) Food web
(c) Pyramid of energy
(d) Trophic levels
Ans.
(c) Pyramid of energy
6. Carbon atoms are circulated and recycled through
(a) Nitrification and denitrification
(b) Photosynthesis and respiration
(c) Respiration and nitrification
(d) Photosynthesis and ammonification
Ans.
(b) photosynthesis and respiration
7. Conversion of ammonia into a nitrite and then nitrate is called
(a) Nitrogen fixation
(b) Denitrification
(c) Nitrification
(d) Ammonification
Ans.
(c) nitrification
8. The conversion of nitrogen compounds into gaseous nitrogen is called
(a) Nitrogen fixation
(b) Denitrification
(c) Ammonification
(d) Nitrification
Ans.
(b) denitrification
9. is an important component of proteins and nucleic acids.
(a) Carbon
(b) Nitrogen
(c) Phosphorus
(d) Oxygen
Ans.
(b) Nitrogen
10. Amount of matter and energy from the lowest level to the highest level.
(a) decreases
(b) increases
(c) remains the same
(d) multiplies
Ans.
(a) decreases
11. is the most important source of energy in any ecosystem.
(a) The Sun
(b) The Moon
(c) Producers
(d) Decomposers
Ans.
(a) The Sun
12. Flow of energy in an ecosystem is
(a) cyclical
(b) two way transport
(c) one way transport
(d) to and fro transport
Ans.
(c) one way transport
13. The Indian Institute of Ecology and Environment, Delhi, has published
(a) Invasive species in a changing Environment
(b) Encyclopaedia of Ecology and Environment
(c) Environment and Ecology Magazine
(d) Biodiversity and Disaster Management
Ans.
(b) Encyclopaedia of Ecology and Environment
14. Oxygen is released in the process of
(a) Respiration
(b) Decomposition
(c) Combustion
(d) Photosynthesis
Ans.
(d) photosynthesis
15. cycle is a gaseous cycle.
(a) Carbon
(b) Phosphorus
(c) Calcium
(d) Iron
Ans.
(a) Carbon
16. is a sedimentary cycle.
(a) Carbon
(b) Nitrogen
(c) Oxygen
(d) Calcium
Ans.
(d) Calcium
17. is a primary consumer.
(a) Elephant
(b) Frog
(c) Owl
(d) Tiger
Ans.
(a) Elephant
18. is a secondary consumer.
(a) Grasshopper
(b) Elephant
(c) Frog
(d) Human
Ans.
(c) Frog
19. Tiger is a
(a) Producer
(b) Primary consumer
(c) Apex consumer
(d) Secondary consumer
Ans.
(c) apex consumer
20. Carbon dioxide is released into the atmosphere through
(a) burning of fossil fuels
(b) volcanic activity
(c) respiration
(d) all of these
Ans.
(d) all of these
21. In 1942 studied the food chain and energy flow through it
(a) Linderman
(b) Darwin
(c) Calypso
(d) Chu win lee
Ans.
(a) Linderman
22. After the death of apex consumers, energy becomes available to
(a) Decomposers
(b) Producers
(c) Herbivores
(d) Carnivores
Ans.
(a) Decomposers
23. Green plants of the ecosystem store in the form of food.
(a) Solar energy
(b) Chemical energy
(c) Thermal energy
(d) Electrical energy
Ans.
(a) Solar energy
24. Plants convert carbon dioxide into by the process of photosynthesis.
(a) Carbohydrates
(b) Proteins
(c) Fats
(d) Vitamins
Ans.
(a) Carbohydrates
25. Carnivores feed upon
(a) Decomposers
(b) Herbivores
(c) Producers
(d) Secondary producers
Ans.
(b) Herbivores
26. is used up in the processes like respiration, combustion, decomposition, corrosion, rusting, etc.
(a) Nitrogen
(b) Oxygen
(c) Argon
(d) Helium
Ans.
(b) Oxygen
27. Nitrogen forms % of the atmosphere.
(a) 79
(b) 78
(c) 21
(d) 2
Ans.
(b) 78
28. Most organisms cannot use the free form of
(a) Oxygen
(b) Nitrogen
(c) Carbon dioxide
(d) Carbon monoxide
Ans.
(b) Nitrogen
29. first proposed the concept of Ecological Pyramid in 1927.
(a) Darwin
(b) Newton
(c) Elton
(d) Edison
Ans.
(c) Elton
30. Ecological Pyramid is called
(a) Hills
(b) Mounts
(c) Eltonian
(d) Darwinism
Ans.
(c) Eltonian
31. is produced from oxygen through various atmospheric processes.
(a) Nitrogen dioxide
(b) Nitrites
(c) Ozone
(d) CFC
Ans.
(c) Ozone
32. Interactions between producers, consumers and saprophytes in a definite sequence is called
(a) Links
(b) Internet
(c) Food chain
(d) Connectors
Ans.
(c) Food chain
33. Many food chains interconnected at various levels is called
(a) Links
(b) Internet
(c) Connectors
(d) Food web
Ans.
(d) Food web
34. Decomposers dissipate some amount of energy in the form of
(a) Light
(b) Electricity
(c) Sound
(d) Heat
Ans.
(d) Heat
35. The flow of nutrients in an ecosystem is
(a) Non- cyclic
(b) Mono directional
(c) Reverse directional
(d) Cyclical
Ans.
(d) Cyclical
36. The cyclical flow of nutrients within an ecosystem is called
(a) Biological cycle
(b) Chemical cycle
(c) Solar cycle
(d) Bio-geo chemical cycle
Ans.
(d) Bio-geo chemical cycle
37. is an accumulation of the main abiotic gaseous nutrient materials found in the earth’s atmosphere.
(a) Gaseous cycle
(b) Water cycle
(c) Solar cycle
(d) Lunar cycle
Ans.
(a) Gaseous cycle
38. Oxygen is released into the atmosphere by the process of
(a) Photosynthesis
(b) Respiration
(c) Oxidation
(d) Decomposition
Ans.
(a) Photosynthesis
39. Charles Elton studied the of the Beer islands in England.
(a) Tundra ecosystem
(b) Mediterranean ecosystem
(c) Equatorial ecosystem
(d) Taiga ecosystem
Ans.
(a) Tundra ecosystem
40. in 1942 studied the food chain and energy flow through it.
(a) Charles Elton
(b) Lindeman
(c) Robert Whittaker
(d) Eichler
Ans.
(b) Lindeman
41. After the death of apex consumers, energy becomes available to
(a) Primary consumer
(b) Secondary consumer
(c) Decomposer
(d) Sun
Ans.
(c) Decomposer
42. Nitrogen forms % of the atmosphere.
(a) 28%
(b) 78%
(c) 48%
(d) 82%
Ans.
(b) 78%
43. first proposed the concept of the Ecological Pyramid in 1927.
(a) Charles Elton
(b) Lindeman
(c) Eichler
(d) John Muir
Ans.
(a) Charles Elton
44. Oxygen is released into the atmosphere by the process of
(a) respiration
(b) Photosynthesis
(c) Combustion
(d) All of these
Ans.
(b) Photosynthesis
3. Find the odd man out:
1. Photosynthesis, Respiration, Decomposition, Forest Fires
Ans.
Forest Fires
2. Combustion, Corrosion, rusting, formation of ozone, Photosynthesis
Ans.
Photosynthesis
3. Biological nitrogen fixation, ammonification, nitrification, denitrification, industrial nitrogen fixation
Ans.
Industrial nitrogen fixation
4. Frog, Owl, Squirrel, Fox
Ans.
Squirrel
5. Grasshopper, squirrel, elephant, lion
Ans.
Lion
6. Nitrogen cycle, oxygen cycle, carbon cycle, phosphorus cycle
Ans.
Phosphorus cycle
7. Photosynthesis, Nitrification, Ammonification, Denitrification
Ans.
Photosynthesis
4. Find out the correlation:
1. Grasshopper : Primary consumer :: Tiger : ………………..
Ans.
Apex consumer
2. Owl : Secondary consumer :: Squirrel : ………………..
Ans.
Primary consumer
3. Flow of energy : One way :: Flow of nutrients : ………………..
Ans.
Cyclic
4. Plants : Producers :: Bacteria and Fungi : ………………..
Ans.
Decomposers
5. Nitrogen : Gaseous cycle :: Phosphorus : ………………..
Ans.
Sedimentary cycle
6. Oxygen : 21% :: Nitrogen : ………………..
Ans.
78%
7. Photosynthesis: Carbon cycle:: Ammonification : ………………..
Ans.
Nitrogen cycle
8. Respiration : Oxygen cycle :: Nitrification : ………………..
Ans.
Nitrogen cycle
9. Respiration : Biotic process :: Combustion : ………………..
Ans.
Abioticprocess
10. Microbes using oxygen : Aerobes :: Microbes not using oxygen : ………………..
Ans.
Anaerobes
5. Difference between:
(1) Azotobacter and Rhizobium
Ans.
Azotobacter | Rhizobium |
Free-living nitrogen-fixing bacteria | Symbiotic nitrogen-fixing bacteria |
(2) Biotic components and Abiotic component
Ans.
Biotic components | Abiotic component |
Living component of an ecosystem | Physical/Chemical non-living components of an ecosystem |
(3) Producers and Herbivores
Ans.
Producers | Herbivores |
They are present in the 1st trophic level | They are present in the 2nd trophic level |
(4) Carnivores and Herbivores
Ans.
Carnivores | Herbivores |
They depend on Herbivores for nutrition | They depend on Producers for nutrition |
(5) Phosphorus and Carbon
Ans.
Phosphorus | Carbon |
It cycles through the Sedimentary cycle | It cycles through the Gaseous cycle |
(6) Food chain and Food web
Ans.
Food chain | Food web |
Interactions between producers, consumers and decomposers in a definite sequence is called as a food chain. | The interconnection among different food chains in an ecosystem at various levels is called as a food web |
6. State whether the following statements are true or false. Correct the false statements:
(1) Herbivores occupy the third trophic level in a food chain.
Ans.
False
Correction:
Herbivores occupy the second trophic level in a food chain.
(2) Apex consumers use herbivores and carnivores as their food.
Ans.
True
(3) Humans are apex consumers.
Ans.
True
(4) Omnivores feed only on carnivores.
Ans.
False
Correction: Omnivores feed on both plants and animals.
(5) A food chain has two links.
Ans.
False
Correction: A food chain usually has four or more links.
(6) The number of consumers in a food web is fixed.
Ans.
False
Correction: The number of consumers in a food web is not fixed.
(7) The amount of matter and energy goes on increasing at every level in a food chain.
Ans.
False
Correction: The amount of matter and energy decreases at every level.
(8) Robert Brown first proposed the concept of Ecological Pyramid.
Ans.
False
Correction: Charles Elton first proposed the concept of the Ecological Pyramid.
(9) After the death of apex consumers, the energy becomes available to decomposers.
Ans.
True
(10) The gaseous cycle is a speedier cycle than the sedimentary cycle.
Ans.
True
(11) Climatic changes and human activities seriously affect the speed, intensity and equilibrium of bio-geo-chemical cycles.
Ans.
True
(12) Carbon dioxide is released in the atmosphere through photosynthesis.
Ans.
False
Correction: Carbon dioxide is absorbed during photosynthesis and released during respiration.
(13) The equilibrium of oxygen and carbon dioxide gases is maintained by decomposers.
Ans.
False
Correction: The equilibrium of oxygen and carbon dioxide is maintained by plants.
(14) The conversion of ammonia into a nitrite and then nitrate is called nitrogen fixation.
Ans.
False
Correction: This process is called nitrification.
(15) Conversion of nitrogen compounds into gaseous nitrogen is called nitrogen fixation.
Ans.
False
Correction: This process is called denitrification.
(16) Release of ammonia through decomposition of dead plants and excretory wastes of organisms is called ammonification.
Ans.
True
(17) The cyclic flow of nutrients within an ecosystem is called Energy Pyramid.
Ans.
False
Correction: The cyclic flow of nutrients is called the bio-geo-chemical cycle.
7. Name the following:
1. The animals that feed on herbivores.
Ans.
Carnivores.
2. Organisms that feed on herbivores and carnivores.
Ans.
Omnivores.
3. Two examples of primary consumers.
Ans.
Grasshopper, squirrel.
4. Two examples of secondary consumers.
Ans.
Frog, owl.
5. Two examples of Apex consumers.
Ans.
Lion, tiger.
6. Levels in the food chain.
Ans.
Trophic level.
7. Organisms that decompose the dead bodies of plants and animals.
Ans.
Decomposers.
8. Process which releases oxygen.
Ans.
Photosynthesis.
9. Release of ammonia through decomposition of dead bodies and excretory wastes of organisms.
Ans.
Ammonification.
10. Conversion of nitrogen into nitrates and nitrites through atmospheric, industrial and biological processes.
Ans.
Nitrogen fixation.
8. One line answers:
1. What is Food chain?
Ans.
A food chain is a sequence showing how energy transfers from one organism to another in an ecosystem.
2. What is Food web?
Ans.
A food web is a network of interconnected food chains in an ecosystem.
3. What is Trophic level?
Ans.
A trophic level is a step or level in a food chain where organisms obtain their energy.
4. What is Pyramid of energy?
Ans.
A pyramid of energy shows the decreasing amount of energy at each trophic level in a food chain.
5. What is Bio-geo-chemical cycle?
Ans.
It is the continuous recycling of nutrients between living organisms and the environment.
6. What is Carbon cycle?
Ans.
The carbon cycle is the movement of carbon through the atmosphere, living beings, and earth.
7. What is Oxygen cycle?
Ans.
The oxygen cycle is the circulation of oxygen between the
environment and living organisms.
8. What is Nitrogen cycle?
Ans.
The nitrogen cycle is the circulation of nitrogen in various chemical forms through nature.
9. What is Nitrogen fixation?
Ans.
Nitrogen fixation is the process of converting nitrogen gas into usable nitrogen compounds.
10. Distinguish between:
1. Difference between Gaseous Cycle and Sedimentary Cycle
Ans.
Gaseous Cycle | Sedimentary Cycle |
Nutrients are stored mainly in the atmosphere. | Nutrients are stored mainly in soil and rocks. |
It includes cycles of carbon, oxygen, nitrogen, etc. | It includes cycles of phosphorus, sulphur, calcium, etc. |
These cycles are usually faster. | These cycles are relatively slower. |
Wind and air currents help in circulation. | Erosion, weathering, and runoff help in circulation. |
Example: Carbon cycle | Example: Phosphorus cycle |
2. Difference between Carbon Cycle and Nitrogen Cycle
Ans.
Carbon Cycle | Nitrogen Cycle |
Involves circulation of carbon. | Involves circulation of nitrogen. |
Carbon is used in photosynthesis and released in respiration. | Nitrogen is fixed by bacteria and used for protein synthesis. |
Main forms: CO₂, carbohydrates, fossil fuels. | Main forms: N₂, ammonia, nitrates, nitrites. |
Helps regulate Earth's temperature. | Helps in plant growth and soil fertility. |
Carried out by plants, animals, decomposers, and combustion. | Carried out by nitrogen-fixing, nitrifying, and denitrifying bacteria. |
11. Write short notes on:
1. Trophic Level:
Ans.
A trophic level is each step or level in a food chain where organisms obtain energy. The first level consists of producers (plants), followed by herbivores, carnivores, and top consumers. Energy decreases as we move up the trophic levels.
2. Food Web:
Ans.
A food web is a complex network of interconnected food chains in an ecosystem. It shows how different organisms are linked through various feeding relationships and provides stability by offering multiple food sources.
3. Energy Pyramid:
Ans.
An energy pyramid is a graphical representation of the flow of energy at different trophic levels in a food chain. It shows that energy decreases at each higher level, with the most energy at the producer level and the least at the apex consumer level.
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