Symbiotic Interactions of Plants and Animals | Jamb Biology

Energy Flow in Ecosystems

1. Definition of Energy Flow: The movement of energy through trophic levels in an ecosystem.
2. Primary Source: The sun provides energy for most ecosystems.
3. Producers (Autotrophs): Convert solar energy into chemical energy through photosynthesis.
4. Consumers (Heterotrophs): Depend on producers for energy.
5. Primary Consumers: Herbivores that feed on producers (e.g., grasshoppers eating grass).
6. Secondary Consumers: Carnivores that eat primary consumers (e.g., snakes eating mice).
7. Tertiary Consumers: Higher-level carnivores that feed on secondary consumers (e.g., eagles eating snakes).
8. Decomposers (Saprophytes): Break down dead organisms, recycling nutrients (e.g., fungi, bacteria).
9. Food Chain: A linear sequence showing energy transfer through trophic levels.
10. Example of a Food Chain: Grass → Grasshopper → Frog → Snake → Hawk.
    
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11. Food Web: A complex network of interconnected food chains.
12. Example of a Food Web: Includes multiple overlapping food chains, like grasses feeding grasshoppers and rabbits, both of which are prey for snakes.
13. Trophic Levels: The positions organisms occupy in a food chain (producers, consumers, decomposers).
14. Energy Transfer Efficiency: About 10% of energy is passed from one trophic level to the next; the rest is lost as heat.
15. Ecological Pyramids:
    • Energy Pyramid: Shows energy flow through trophic levels.
    • Biomass Pyramid: Represents the amount of living matter at each level.
    • Number Pyramid: Displays the number of organisms at each level.
16. Significance of Energy Flow: Supports life, maintains ecosystem balance, and drives nutrient cycles.
17. Keystone Species: Play a critical role in maintaining food web stability (e.g., sea otters).
18. Omnivores: Consume both plants and animals, linking multiple food chains.
19. Impact of Disturbances: Habitat destruction or species extinction can disrupt energy flow.
20. Human Influence: Pollution, overhunting, and agriculture alter energy dynamics in ecosystems.
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Interactions Among Organisms

Symbiosis

21. Definition: A close, long-term interaction between two species.
22. Mutualism: Both species benefit (e.g., bees pollinating flowers).
23. Commensalism: One species benefits, the other is unaffected (e.g., barnacles on whales).
24. Parasitism: One species benefits at the expense of the other (e.g., ticks feeding on dogs).
25. Amensalism: One species is harmed while the other is unaffected (e.g., Penicillium producing antibiotics that kill bacteria).
    
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Saprophytism

26. Definition: Decomposers obtain nutrients by breaking down organic matter (e.g., fungi on dead logs).
27. Role in Ecosystems: Recycles nutrients into the soil.
    
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Competition

28. Definition: Organisms compete for resources like food, space, and light.
29. Example: Lions and hyenas competing for prey.
30. Types:
    • Intraspecific: Competition within the same species (e.g., plants competing for sunlight).
    • Interspecific: Competition between different species (e.g., birds and squirrels competing for nuts).
      
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Predation

31. Definition: One organism (predator) feeds on another (prey).
32. Example: Lions preying on zebras.
33. Impact on Populations: Regulates prey populations and maintains ecosystem balance.
    
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Cooperation

34. Definition: Members of the same species work together for mutual benefit (e.g., ants building a colony).
35. Example: Dolphins hunting in groups to herd fish.
    
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Food Chains, Food Webs, and Habitat Distribution

41. Role of Producers: Form the base of food chains in terrestrial and aquatic habitats.
42. Aquatic Food Chains: Algae → Zooplankton → Small Fish → Larger Fish → Sharks.
43. Desert Food Chains: Cactus → Insects → Lizards → Snakes → Hawks.
44. Distribution of Organisms:
    • Herbivores are abundant where producers thrive (e.g., savannahs).
    • Predators depend on prey availability, influencing their distribution.
45. Food Chains in Forests:
    • Trees → Caterpillars → Birds → Hawks.
46. Effect of Disturbances: Habitat loss disrupts food chains and webs.
47. Role of Keystone Species: Their absence can collapse entire food webs.
48. Ecosystem Productivity: Biodiverse ecosystems have more stable food webs.
49. Invasive Species: Can disrupt food webs by outcompeting native species.
50. Human Activities: Overfishing and deforestation simplify food chains, reducing ecosystem resilience.
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The Carbon Cycle

51. Definition of the Carbon Cycle: The movement of carbon between the atmosphere, biosphere, hydrosphere, and geosphere.
52. Processes in the Carbon Cycle:
    • Photosynthesis: Plants absorb CO₂ to produce glucose.
    • Respiration: Organisms release CO₂ during energy production.
    • Decomposition: Dead organisms release carbon into the soil.
    • Combustion: Burning fossil fuels releases CO₂.
53. Significance: Maintains a balance between atmospheric oxygen and CO₂.
54. Role of Oceans: Act as carbon sinks, absorbing CO₂.
55. Impact of Deforestation: Reduces CO₂ absorption by plants, increasing atmospheric carbon.
56. Global Warming: Excess CO₂ traps heat, leading to climate change.
57. Carbon Sequestration: Capturing and storing atmospheric CO₂ to mitigate global warming.
58. Role of Microorganisms: Decompose organic matter, recycling carbon.
59. Fossil Fuels: Store carbon from ancient plants and animals.
60. Greenhouse Effect: Necessary for life but intensified by human activities.
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The Water Cycle and Its Effect on Nutrient Cycles

61. Definition of Water Cycle: The movement of water through evaporation, condensation, precipitation, and runoff.
62. Evaporation: Converts water from liquid to vapor.
63. Condensation: Vapor forms clouds.
64. Precipitation: Returns water to the earth as rain, snow, or sleet.
65. Runoff: Water flows into rivers, lakes, and oceans.
66. Infiltration: Water seeps into the soil, replenishing groundwater.
67. Effect on Nutrient Cycles:
    • Nitrogen Cycle: Rain dissolves nitrogen compounds, aiding their absorption by plants.
    • Carbon Cycle: Water facilitates photosynthesis and dissolves atmospheric CO₂.
68. Role in Ecosystems: Supports plant growth and maintains aquatic habitats.
69. Human Impact: Damming rivers alters water flow, affecting nutrient distribution.
70. Climate Change: Alters precipitation patterns, disrupting nutrient cycles.
    
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Nitrogen Cycle and the Role of Bacteria

71. Definition of Nitrogen Cycle: The movement of nitrogen through the atmosphere, soil, and living organisms.
72. Nitrogen Fixation:
    • Carried out by bacteria like Rhizobium in leguminous plant roots.
    • Converts atmospheric nitrogen (N₂) into usable forms like ammonia.
73. Nitrification: Bacteria convert ammonia into nitrites and nitrates.
74. Assimilation: Plants absorb nitrates for protein synthesis.
75. Ammonification: Decomposers break down organic matter, releasing ammonia.
76. Denitrification: Bacteria convert nitrates back to N₂ gas, returning it to the atmosphere.
77. Significance: Ensures nitrogen availability for plants and animals.
78. Role of Leguminous Plants: Enhance soil fertility by hosting nitrogen-fixing bacteria.
79. Impact of Fertilizers: Excessive use disrupts the nitrogen cycle, causing eutrophication in water bodies.
80. Global Importance: Nitrogen is essential for DNA, proteins, and chlorophyll synthesis.

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