Ecology

• State the levels of organisation in an ecosystem:

  Individual, population, community, ecosystem
• State the factors that plants may compete for:

  Light

  Space

  Water

  Mineral ions from soil
• State the factors that animals might compete for:

  Food

  Mates

  Territory
• What is intraspecific competition?

  Competition within a species
• What is interspecific competition?

  Competition between different species
• What is interdependance?

  Mutual reliance or dependence between two or more species
• Abiotic factors affecting an ecosystem:

  Light intensity

  Temperature

  Moisture

  Soil pH and mineral content

  Wind intensity and direction

  Carbon dioxide level

  Oxygen level
• Why might light intensity affect an ecosystem?

  Different species of plants may have different optimum light intensities for growth
• How does moisture level affect an ecosystem?

  Many plants cannot survive in waterlogged soil as their roots cannot respire
• Give three examples of extreme living environments:

  High temp

  High pressure

  High salt concentration
• Where can extremophile bacteria be found?

  In deep sea vents
• Define population:

  A species that occupy the same habitat
• Define community:

  Populations of different species interacting
• Define ecosystem:


  The interactions between biotic and abiotic factors in an area
• Define biomass:

  The total mass of living material
• What do arrows in a food chain represent?

  The direction of biomass transfer
• Describe a simple food chain:

  Producer-> primary consumer-> secondary consumer-> tertiary consumer
• Describe how materials cycle through the living and non living components of an ecosystem:

  > Organisms take in elements from their surroundings

  > Elements converted to complex molecules which become biomass

  > Elements transferred along food chains

  > Elements returned to environment during excretion and decomposition of dead organisms
• Describe the carbon cycle:


  > Plant fix carbon dioxide into organic molecules during photosynthesis

  > The organic carbon containing molecules are passed into organisms that eat the plants

  > Carbon dioxide is released back into the atmosphere by respiration from animals and plants

  > Burning fossil fuels also releases carbon dioxide back into the atmosphere
• Describe the water cycle:

  > Water from lakes and oceans evaporates

  > The evaporated water condenses into clouds and returns to earth as precipitation

  > The water from precipitation is useful to life on land

  > The water then returns to rivers and oceans through surface runoff
• Why are microorganisms important for the cycling of materials through an ecosystem

  Microorganisms return carbon to the environment by releasing carbon dioxide through respiration while they decompose dead matter

  The decomposition of dead matter in soil returns mineral ions to the environment for other organisms to use
• How do decomposers break down dead matter?

  They release enzymes which catalyse the breakdown of dead material into smaller molecules
• How does soil water content affect the rate of decomposition?

  > In moist conditions, the rate of decomposition is high

  > In waterlogged soils there is little oxygen for respiration so the rate of decomposition decreases
• Why does decomposition require water?

  Water is required for the secretion of enzymes and absorption of dissolved molecules
• How does sulfur dioxide impact the environment?

  Formed when fossil fuels containing impurities are burnt

  Sulfur dioxide can dissolve in water to form acid rain which can erode buildings and pollute water sources
• How does carbon monoxide impact the environment?

  Carbon monoxide is formed from the incomplete combustion of fossil fuels

  Carbon monoxide binds irreversibly to haemoglobin which prevents it from carrying oxygen
• Name 5 greenhouse gases:

  Water vapour

  Carbon dioxide

  Nitrous oxide

  Methane

  CFCs
• How do greenhouse gases lead to global warming?

  Greenhouse gases allow heat from the sun to enter the atmosphere

  The gases act as a blanket and trap the heat in the atmosphere
• Why is biodiversity important?

  To maintain the stability of an ecosystem because it reduces dependance on one particular species for resources
• How does eutrophication occur?

  > Fertiliser from farms pollute the water, causing excessive algae growth, depleting the oxygen in the water, causing other plants and animals to die

  > Dead plants are decomposed by bacteria and the oxygen levels decrease further
• What does a food chain show?

  the feeding relationships between organisms and the resultant stages of biomass transfer
• How do decomposers break down dead matter?

  > decomposers release enzymes which catalyse the breakdown of dead material into smaller molecules

  > soluble small food molecules then diffuse into the microorganisms
• What is biomass?


  the dry mass if all the living organisms in an area
• Why is dry mass used for biomass?

  Because wet mass varies as the volume of water in the organism varies
• What percentage of the incident energy from light or for photosynthesis do producers transfer?

  1%
• What percentage of the biomass from one trophic level is transferred to the level above it in feeding?

  10%
• What biological factors threaten food security?

  rising birth rates

  new pathogens

  environmental changes affecting food production
• Advantages of intensive farming:

  higher yield of food

  more efficient

  allows easier quality control
• Disadvantages of intensive farming:

  may lead to antibiotic resistance

  cost is high

  ethical objections

  biodiversity may be reduced
• What is mycoprotein? 


  a protein rich substance used to make meat substitute food for vegetarians and vegans