Bio Chap 13 - Organism and their Environment

• Living organisms can be classified as producers, consumers, or decomposers depending on their mode of nutrition
• Producers make their own food by photosynthesis
• Consumers obtain nutrients by feeding on other organisms

  • Primary consumers feed on producers
  • Secondary consumers feed on primary consumers
  • Tertiary consumers feed on secondary consumers
• Decomposers obtain nutrients by breaking down dead matter and excretory products
• Trophic level refers to the position of an organism on a food chain
• A food chain shows the linear flow of energy from organism to organism
• A food web consists of a network of interconnected food chains
• An organism can only be at 1 trophic level in a food chain, but can be at more than 1 trophic level in a food web
• The flow of energy in an ecosystem is non-cyclical (linear)
• The ultimate source of energy is the Sun
• Producers absorb light using chlorophyll and photosynthesize to produce glucose (stores of chemical energy)
• Around 90% of energy is lost at each trophic level

  • Heat through respiration
  • Metabolic processes such as growth and repair of cells
  • Chemical energy through excretory products, uneaten body parts
• An animal that feeds on another animal is a predator
• An animal that is eaten by another animal is the prey
• Predator and prey populations are correlated and fluctuate with time
• Pyramid of numbers shows the number of organisms at each trophic level at a particular point in time
• Pyramid of biomass shows the standing/dry mass at each trophic level at a particular point in time
• Carbon is constantly released and removed from the atmosphere in the form of carbon dioxide
• The carbon cycle involves several processes involving the release and removal of carbon dioxide

  • Photosynthesis: CO2 is absorbed from the atmosphere and used to synthesize glucose
  • Respiration: CO2 is released into the atmosphere when organisms carry out respiration to release energy
  • Decomposition: CO2 is released into the atmosphere when decomposers break down organic matter
  • Combustion: CO2 is released into the atmosphere when fossil fuels are burnt
• Carbon sinks are areas that store carbon from the atmosphere for a long period of time
• The Ocean: Carbon dioxide dissolves in the water and is used by aquatic plants and coral reefs for photosynthesis

  • Forests: Carbon dioxide is absorbed by plants and stored in the form of carbohydrates
• Deforestation and use of fossil fuels have negative effects on the environment

  • Concentration of carbon dioxide in the atmosphere increases
  • Effects of carbon dioxide pollution include the greenhouse effect and ocean acidification
• Ways to reduce the effects of Global Warming:

  • Reduce use of fossil fuels, use renewable sources of energy
  • Reduce energy consumption
  • Use hybrid or electric vehicles
  • Conserve forests
• Pollution is the process where harmful substances are added to the environment, threatening life
• Sewage may contain disease-causing bacteria and nutrients for algae, leading to eutrophication
• Insecticides may become ineffective over time and accumulate in organisms, leading to biomagnification
• Plastics are non-biodegradable and harmful to the environment, causing harm to marine life through ingestion
• Conservation is crucial for preserving biodiversity and a sustainable ecosystem

  • Preventing extinction of species
  • Providing useful information about the world through studying wildlife
  • Maintaining a stable and balanced ecosystem
  • Preserving natural scenery and wildlife for appreciation