7.2 Organisation of an Ecosystem

• What are photosynthetic organisms?

  The producers of biomass for life on Earth. They produce their own food using energy from the Sun
• What are the characteristics of a producer?

  • They are at the start of every food chain
  • They can photosynthesise
  • They make glucose by photosynthesis
  • The glucose is used to produce other biological molecules, which then make up the producer's biomass
• What do food chains show?

  The feeding interactions between the organisms in a community and the transfer of energy from one organism to the next
• What is ecology?

  The branch of biology that studies the distribution and abundance of species, the interactions between species, and the interactions between species and their abiotic environment
• What are quadrats and what are they used to measure?

  Quadrats are square frames placed on the ground to measure the abundance of plants or slow-moving animals
• Give 3 ways quadrats can be used to measure abundance

  • Number of an individual species
  • Species richness (the total number of different species)
  • Percentage cover (the approximate percentage of the quadrat area in which a species i s recorded, used when it is difficult to count individuals of the species)
• What is a transect and what are they used to measure?

  A transect is a line (tape measure) set up through a changing habit used to measure how the abundance of a species changes as you move along a changing habitat.
• How is a transect used?

  1. A line (transect) is set up through the changing habitat you want to investigate with a tape measure
  2. A quadrat is then placed at regular intervals along the transect
  3. At each interval the quadrat can be used to record the number of an individual species, species richness or percentage cover
• Why are transects useful?

  They're useful for investigating how the abundance of a species is affected by an abiotic factor
• What are predators and prey?

  • Predators - consumers that kill and eat other animals
  • Prey - animals which are eaten
• What are the numbers of predators and prey like in a stable community?

  In a stable community the number of predators and prey rise and fall in cycles
• Why are all materials in the living world recycled?

  To provide the building blocks for future organisms
• Elements such as carbon are not endless resources. Why are they recyled?

  To allow new organisms to be made and grow
• Explain the carbon cycle

  A) Carbon dioxide

  B) plants

  C) algae

  D) glucose

  E) carbohydrates

  F) biomass

  G) feed

  H) respiration

  I) plants

  J) dead remains

  K) waste products

  L) fossil

  M) fuels

  N) millions

  O) pressure

  P) carbon dioxide

  
• Give an overview of the carbon cycle

  The carbon cycle returns carbon from organisms to the atmosphere as carbon dioxide to be used by plants in photosynthesis
• Give an overview of the water cycle

  The water cycle provides fresh water for plants and animals on land before draining into the seas. Water is continuously evaporated and precipitated.
• Explain the water cycle

  1. Energy from the sun evaporates water from the land and sea, turning it into water vapour. Water also evaporates from plants (transpiration)
  2. Warm water vapour is carried upwards and once high enough cools and condenses to form clouds
  3. Water falls to the ground as precipitation, providing freshwater for animals and plants
  4. This water drains into the sea, starting the process again
• Why is the carbon cycle important?

  Carbon-containing molecules such as glucose are important for living organisms to grow and provide energy for vital functions within cells
• Why is the water cycle important?

  Living organisms require water and the water cycle provides organisms on land with a continuous supply of water
• What is the role of microorganisms in cycling material through an ecosystem?

  They return carbon to the atmosphere as carbon dioxide and mineral ions to the soil
• What is decomposition?

  The process by which waste products or dead organisms are broken down by decomposers into organic matter and the materials they contain are returned to the environment
• What 3 things affect the rate of decay?

  Temperature, water and availability of oxygen
• What are the two types of decomposers?

  • Microorganisms - bacteria and fungi
  • Detritus feeders - e.g. earthworms and woodlice
• How does temperature affect the rate of decay?

  • At warmer temperatures, enzymes involved in decomposition work at a faster rate, increasing rate.
  • If the temperature is too high, the enzymes will denature and the rate will decrease
  • At low temperatures, enzymes involved in decomposition work slowly, decreasing rate (hence why we keep food in a fridge)
• How does water affect the rate of decay?

  • Decomposers require water to survive
  • Water is required for the secretion of enzymes onto decaying decaying biological matter and absorbing the products of the chemical digestion
  • As water availability decreases, so does the rate of decay
• How does oxygen affect the rate of decay?

  • Oxygen is needed by many decomposers for aerobic respiration - without it they cannot survive
  • For these decomposers, the rate decreases as oxygen availability decreases
  • However some can respire anaerobically, resulting in anaerobic decay to release mixtures of gases like methane (biogas)
• What 3 optimum conditions do gardeners and farmers try to provide for rapid decay of waste biological material?

  Warmth, moisture and oxygen supply
• What is compost and what is it used as?

  Compost is nutrient-rich decomposed organic matter, used as a natural fertiliser for growing garden plants or crops
• Explain how compost is used and how it works

  • The compost is spread onto the soil, and it is broken down further by decomposing microorganisms and detritivores
  • This ensures the recycling of minerals that can then be absorbed by plants to be used for growth
• What is biogas?

  Methane gas produced by anaerobic decay
• What are biogas generators?

  Large containers in which animal or plant waste is allowed to decay anaerobically to produce methane gas
• What conditions should be present in a biogas generator?

  • Anaerobic conditions - no oxygen
  • Moisture for microorganisms to survive
  • Constant, optimum temperature
• What can environmental change affect?

  The distribution of species within ecosystems
• Give 3 examples of changing environmental factors which can affect the distribution of organisms

  • Temperature
  • Availability of water
  • Composition of atmospheric gases
• What are the 3 types of changing environmental factors?


  Seasonal, geographic or caused by human interaction
• How does temperature affect distribution?

  • Organisms have adaptations that enable them to survive within a certain temperature range
  • If temperature is too low, growth will be slower as organisms use more energy for keeping warm
  • If temperature is too high, organisms will die, and water will become limited as evaporation increases
  • As climate change occurs and average temperatures rise, the distribution of species is changing
• How does availability of water affect distribution?

  • All organisms require water to survive (e.g. drinking, habitats)
  • Animals may migrate to find water
  • Melting ice caps destroys habitats of some animals
• How do atmospheric gases affect ecosystems?

  • Some organisms cannot survive when certain gases are present
  • Some species are very sensitive to air pollution
  • Polluted water can cause illnesses to those who drink it
• What impacts can sulfur dioxide have on the environment?

  Sulfur dioxide is produced during certain industrial processes due to the combustion of fossil fuels. Sulfur dioxide can dissolve in water to form acid rain and erodes buildings and pollute water sources
• How do you calculate the total population size when sampling?

  Total population size = (total area / area sampled) x number of organisms of species counted in sample