Ecology notes

• Food Chains, Food Webs & Energy Pyramids


  • primary/secondary consumers
  • producers
  • decomposers
• Energy Cycling in Ecosystems

  1. Photosynthesis

  2. Cellular respiration
• Cycles


  • Carbon cycle
  • Nitrogen cycle
  • Phosphorus cycle
  • Water cycle

  
• Eutrophication


  Too much nitrogen enters an aquatic ecosystem

  
• Pesticides and bioaccumulation


  • Bioaccumulation
  • Bioamplification
• Bioaccumulation


  Buildup of substances in an organism
• Bioamplification


  Increase in concentration of a substance in organisms at higher levels of a food chain
• Invasive species


  • Control of Invasive Species
• Limiting factors


  Factors that restrict the growth and development of organisms
• Autotrophs / producers


  Organisms that make their own food either using sun's energy for photosynthesis or chemical energy for chemosynthesis
• Heterotrophs / consumers


  • Primary consumers
  • Secondary consumers
  • Tertiary consumers
  • Quaternary consumers
• Decomposers


  Break down dead organisms and organic matter to obtain chemical energy, recycling materials in the process
• Energy Flow


  Different levels called tropic levels in an energy pyramid (represent a food chain), most limited to 4-5 levels due to inefficient energy transfer
• 10% Energy Transfer Rule - around only 10% of energy stored as biomass in one tropic level ends up biomass in the next tropic level
• The higher level needs to consume more to sustain themselves
• The biggest source of energy loss is cellular respiration. Cellular respiration is needed to carry out life processes, like movement, transport of molecules and reproduction. It releases heat energy, which is lost to the environment.
• Not all of the food at each level is eaten, e.g. plant roots and bones of animals, so the energy from these part is lost.
• Most energy is lost as heat which is produced cellular respiration. Some energy is also lost when an organism lives without being eaten, and when parts of an organism are either not eaten or are not consumed, e.g. bones
• Decomposers


  Organisms that break down waste and living matter, gaining energy for themselves and releasing nutrients back into the environment
• If a population of a species is lost from an ecosystem, it can have devastating consequences. If there are other species that depend upon it as a food source, their numbers can decline rapidly. This has a knock-on effect on the entire ecosystem.
• Types of animals


  • Predators
  • Herbivores
  • Apex Predators
  • Carnivores
  • Omnivores
  • Scavengers
• Levels of biological organisation

  • Cell
  • Tissue
  • Organ
  • Organ system
  • Organism
  • Population
  • Community
  • Biome
  • Ecosystem
  • Biosphere
• Pyramid of Biomass is an inverted pyramid
• Photosynthesis


  Foundational process where plants use water, sunlight, and carbon dioxide to create oxygen and glucose, converting the sun's radiant energy into chemical energy
• Chemical equation for photosynthesis: 6CO2 Carbon dioxide + 6H2O Water → (light)→ C6H12O6 Glucose + 6O2 Oxygen
• Cellular respiration


  Process where an organism breaks down food in the presence of oxygen and extracts the energy, with carbon dioxide and water as waste products
• Chemical equation for cellular respiration: Glucose + oxygen → (energy released) → carbon dioxide + water
• Cycles


  • Carbon cycle
  • Nitrogen cycle
  • Phosphorus cycle
  • Water cycle

  
• Carbon is an element that takes the solid form of either graphite or diamond, and all living things are made out of carbon
• Cellular Respiration by plants, animals and decomposers releases CO2

  Burning of fossil fuels by humans releases CO2
• Photosynthesis by plants and algae removes CO2 from the atmosphere

  Dissolving CO2 in the oceans - used by marine life to build shells and exoskeletons
• Breakdown of dead organisms and animals waste (from plants and animals) by decomposers
• Fossilization of dead animals and plants under certain conditions can produce fossil fuels → combustion by humans
• Human impacts on the carbon cycle include deforestation, burning fossil fuels, and climate change causing melting permafrost

  
• Nitrogen Cycle


  1. Fixation

  2. Nitrification

  3. Assimilation

  4. Ammonification

  5. Denitrification

  
• Nitrogen is a necessary component of life as plants need it to grow and animals need it to create DNA

  
• The speed of decomposition is the key to keeping the nitrogen cycle moving as the majority of fixated nitrogen comes from bacteria breaking down dead matter and feces

  
• Warmer areas have faster decomposition
• Nitrogen fixing bacteria supply nitrogen to plants, receiving carbohydrates in exchange

  
• Nitrifying bacteria convert ammonium into nitrates that plants can absorb