Organisms and their environment

• The sun is the main source of energy in ecosystems, providing light energy that is absorbed by chlorophyll and converted into chemical energy
• Energy in producers is transferred from one trophic level to another by feeding, with energy being lost as heat to the environment through respiration
• Heat energy lost to the environment through respiration cannot be recycled in the ecosystem
• Egested and excretory products, as well as dead organisms, contain trapped chemical potential energy that decomposers use for their needs
• The rest of the energy is lost as heat
• There are 3 main groups in ecosystems: producers, consumers, and decomposers
• Producers are the first trophic level in a food chain, they make food by photosynthesis, are usually plants, and provide food and energy for the next trophic level
• Consumers obtain energy by feeding on other organisms, with types including:

  • Primary consumer: herbivores that only feed on plants
  • Secondary consumer: carnivores that feed on animals that are primary consumers
  • Tertiary consumer: carnivores that feed on animals that are secondary consumers
• Decomposers obtain energy by breaking down dead organisms, faeces, and excretory products, such as fungi
• Energy transfer between trophic levels:

  • 90% of the energy is lost to the environment as it is transferred from one trophic level to another
  • Only 10% of that energy is transferred to the next trophic level
  • Energy is lost as heat energy by respiration, decomposers breaking down matter, and uneaten body parts
• Short food chains are efficient because:

  • Only a small amount of energy is transferred from one trophic level to the next
  • Energy is lost as heat energy by respiration through every trophic level
  • Only 10% of the energy is transferred to another trophic level
  • 90% of this energy is lost to the environment
  • By the time this energy reaches the 4th trophic level, only a small amount of energy is transferred
• Importance of carbon cycles:

  • Ensures a continuous supply of carbon dioxide for photosynthesis
  • Ensures energy flow through the ecosystem
  • Maintains the correct amount of carbon dioxide in the environment
• Carbon dioxide is released into the environment by:

  • Respiration: breaking down of glucose in the presence of oxygen releases carbon dioxide
  • Decomposition: after living organisms die, decomposers break down the bodies, releasing carbon dioxide
  • Combustion of fossil fuels: burning crude oil and natural gas releases carbon dioxide
• Roles of forests and oceans as carbon sinks:

  • Carbon sinks store a large amount of carbon dioxide
  • Oceans:
  • Photosynthesis: carbon dioxide dissolves into the ocean, reducing atmospheric carbon dioxide
  • Fossilization: carbon dioxide can be transferred through the food chain, stored in organisms that sink to the ocean bottom
  • Forests:
  • Photosynthesis: plants in forests take in carbon dioxide, storing it as carbon compounds
  • Fossilization: dead plants in forests undergo fossilization, storing carbon for a long time
• Global warming refers to a rise in global temperature due to the concentration of greenhouse gases, while climate change includes long-term changes in climate like wind patterns and temperature
• Deforestation:

  • Removal of multiple trees and plants
  • Forests, acting as carbon sinks, take in large amounts of carbon dioxide through photosynthesis and store it as carbon compounds for a long time
  • When trees are cleared, the stored carbon is released into the environment
• Burning fossil fuels releases carbon dioxide into the atmosphere, leading to more trapped carbon dioxide and increased temperatures, contributing to global warming
• Reforestation involves planting new trees to replace those that have been destroyed, while the designation of land as forest reserves helps protect and preserve carbon sinks