CB9 - Ecosystems & Material Cycles

• What is an ecosystem?

  All the organisms and their environment can be classified as the ecosystem.
• Complete the classifications:

  individual -> population -> community (within a habitat) -> ecosystem
• What are producers?

  Plants or algae, which photosynthesise and produce biomass. They feed the rest of the food chain.
• Who are decomposers and what is their function?

  Decomposers are bacteria and fungi, who break down dead organisms in a process called decomposition.
• How do decomposers decompose?

  They release enzymes onto the dead matter and consume the broken down substances. They play a key role as they fertilise the soil due to the nutrients who get absorbed after decomposition.
• What is abundance?

  A measure of how common something is in an area.
• What is the population size formula?

  $population\space size =$$number\space of \space organisms \space in \space all \space quadrats \space\times\space total\space size \space of \space area \space where \space organism\space lives / total \space area \space of \space quadrats$
• What are abiotic factors?

  Non- living factors that may affect a specie or shape an environment
• Give three examples of abiotic factors:

  1. light intensity
  2. carbon dioxide concentration
  3. water abundance (drought)
• What is one consequence of abiotic factors on organisms in that ecosystem?

  Abiotic factors lead to adaptations from organisms in order to survive.
• What is distribution?

  Distribution of organisms is where they are found in an ecosystem.
• The effect of abiotic factors on distribution can be measure using a belt transect - e.g. practical involving light intensity and flowers => less flowers in a shaded area due to lower amount of light intensity.
• What are biotic factors?

  Biotic factors are living factors, such as organisms, that affect the overall ecosystem or environment.
• State one biotic factor:

  1. Size of population of a predator or prey
• What happens when there are more than one predator in an specific ecosystem?

  Competition for food and shelter.
• What is the predator-prey cycle?

  Interactions between prey and predator that cause directly proportional changes in their population numbers - e.g. once the predator has eaten a large amount of the prey's population, its population decreases due to the lack of food, and therefore the prey's population increases due to less predation, continuing in a cyclical nature.
• What is biodiversity?

  The variety of different species in a specific area.
• What is parasitism?

  When only one organism benefits from a relationship - this usually occurs when the parasite is feeding from its host, hurting the other party.
• What is mutualism?

  When both organisms benefit from a relationship - e.g. flowers and bees - bees get food and flowers reproduce
• What is fish farming?

  Fish farming is a process to reduce overfishing in which fishes are controlled and bred for food.
• What are the problems of fish farming?

  Fish are kept in a relatively small space so uneaten food, faeces sink to the bottom. These conditions may harm the organisms living there (fish + plants) and lead to the spread of parasites and disease.
• Eutrophication

  The addition of more nutrients to an ecosystem than it already has
• Eutrophication

  • Through the use of fertiliser
• Eutrophication

  1. Farmers use fertilisers to grow crops more efficiently

  2. When it rains, fertiliser is absorbed by the water and transported down towards rivers and lakes by the soil or streams of water

  3. Algae grows excessively

  4. Blocking sunlight to the bottom of the lake

  5. Killing any plants beneath it

  6. Fish have less oxygen

  7. High amounts of carbon dioxide

  8. Fish dying by suffocation

  9. Decomposers also use the already low amounts of oxygen
• Carbon Cycle: which organisms are involved in the carbon cycle and how they are involved?

  Plants, animals, decomposers and the combustion of fossil fuels. Plants use carbon dioxide for photosynthesis & release it during respiration, and animals release CO2 during respiration, fossil fuels release CO2 during combustion and decomposers release it during respiration.
• Nitrogen Cycle: what are the way nitrogen cycle through the atmosphere?

  Nitrogen gas (about 78% of our atmosphere) is converted to nitrate compounds by nitrogen fixing bacteria and by lightning striking the soil - link to the Haber Process.
• What is the Haber Process?

  Man-made process to convert nitrogen to ammonia which is used to make fertilisers, increasing crop growth.