Decay and the carbon cycle

• Why do living organisms remove materials from the environment?

  Growth
• What are examples of the material removed from the environment?

  carbon - from carbon dioxide photosynthesis, hydrogen, oxygen, nitrogen
• How are the materials passed on into other organisms?

  feeding relationships
• How are materials returned?

  urine, faeces carbon dioxide and water ( produced respiration ). When living things die and decay
• How is carbon dioxide returned to atmosphere through decay?

  animals and plants decomposed by bacteria. bacteria release mineral ions into soil form animals. plants take up mineral ions through xylem and release carbon dioxide when respiring
• What happens in a stable community?

  processes that remove materials balanced by processes that return materials
• What are detritus feeders?

  maggots beetles worms, begin decay process by eating dead material. release some of waste material through respiration, faeces and urine
• What are the best conditions for decay?

  warm temperature speeds up chemical reactions when temp too hot or too cold enzymes denature. moisture in air food easier to dissolve microbes not dry out. oxygen microbes need respire
• What is compost made from?

  Kitchen and garden waste use by products of harvesting fruit and veg, rotting down manure from animals
• What does compost act as and why?

  natural fertiliser for plants and crops full of nutrients returns minerals to soil improve soil structure and water retention
• What conditions make compost production rapid?

  good supply of oxygen, optimum temperature- 30 degrees enzymes denature at 70 degrees decomposition stop
• Why is compost production faster with oxygen?

  oxygen needed respiration, respiration release energy for organisms move and reproduce
• What happens when waste material decomposed without oxygen?

  Bacteria break down organic waste in biogas generator methane produced, methane use in heating, cooking, generating electricity
• What is the specific term for how methane produced?

  aerobic fermentation of wide range of waste products and plant material containing carbohydrate e.g sugar factory waste
• What type of process is anaerobic respiration?

  exothermic
• What can be used in anaerobic fermentation?

  Slurry fertiliser
• What is there produced by methane un large amounts ad material being put in generator?

  lag time
• Why are biogas generators underground?

  more suitable provide fuel underground
• How are the optimum conditions maintained for biogenerator underground?

  walls insulated with thick layer of concrete
• What is a down side to biogas?

  not able be stored as liquid has to use straight away e.g. heating, cooking, lighting, power turbine to generate electricity
• What happens in a continuous biogas generator?

  Digester continually fed for long periods of time at steady rate
• What are the advantages and disadvantages of continuous generators?

  Advantages: efficient, methane continually produced, continuous use of waste materials. Disadvantages: more expensive to set up more complex, needs continuous feed of waste, cant control temperature slow in winter
• What happens in a batch generator?

  gas collected, tank cleaned then refilled, digested material collected to be fertiliser
• What are the advantages and disadvantages of batch generators?

  Advantages: useful small scale production, cleaned easily if contaminated. Disadvantages: take time and energy set up, methane production take long time, only small batches of biogas produced
• Required practical effect of temperature on rate of decay?

  Place fresh milk into three beakers. Decide three different temperatures. Use universal indicator determine ph of milk. Cover beakers with cling film incubate at temperatures. Use universal indicator paper on solution to determine ph of milk after 24 48 and 72 hours
• Wha are the independent and dependant variables in the decay experiment?

  Independent : temperature dependant : ph of solution
• What are the control variables in decay experiment?

  volumes of solution, volume of universal indicator
• Why does the Ph of milk decay as it reduces?

  bacteria respire to provide them with energy. some of glucose used for respiration converted into lactic acid. lactic acid has ph of 3
• What are the stages of the water cycle?

  water evaporates from surface of sea. heat and wind speed up process. water vapour in atmosphere cool down condense to form water droplets some water droplets fall as rain
• How can carbon compounds be recycled to be used again by trees?

  microorganisms break down animal and plant material. plant roots absorb minerals from animal and plant through diffusion in root carbon dioxide released when plant photosynthesise
• What environmental conditions speed up chemical processes?

  warm, humid, oxygen , suitable pH