B4h Recycling CO2 Carbon is one element that is recycled naturally The Carbon Cycle CO2 respiration CO2 CO2 BURNING CO2 released Photosynthesis Carbon compounds in plants Useful products feeding death Fossil fuels Compaction 100,000+ years Carbon compounds in soil being decayed by bacteria

B4h Recycling The processes which remove materials are balanced by the processes which return materials. The materials are constantly cycled The constant cycling of carbon is called the carbon cycle. In the carbon cycle: carbon dioxide is removed from the air by green plants for photosynthesis; they use it to make carbohydrates, fats and proteins which make up the body of plants; some of the carbon dioxide is returned to the atmosphere when green plants respire; when green plants are eaten by animals, some of the carbon becomes part of the carbohydrates, fats and proteins which make up their bodies; when animals respire some of this carbon becomes carbon dioxide and is released into the atmosphere; when plants and animals die, some animals and microorganisms feed on their bodies; carbon is also released into the atmosphere as carbon dioxide when these organisms respire

B4h Recycling Complete the diagram of the carbon cycle Atmospheric carbon dioxide Green plants Carnivores Microorganisms Respiration Photosynthesis Excretion, defaecation, death and decay Feeding Death and decay Herbivores

B4h Recycling The Nitrogen Cycle Dead rabbit Denitrifying bacteria Nitrogen fixing bacteria live in root nodules of some plants Denitrifying bacteria Nitrogen gas Nitrates Dead rabbit Absorbed by plants and used to make amino acids Plant gets nitrogen it can use to make proteins The proteins in the rabbit are digested by fungi and bacteria Nitrifying bacteria Nitrates ammonia urea So, on Monday a nitrogen molecule could be in the eye of a rabbit. By the following Sunday, it is in the leaf of a plant

B4h Recycling Nitrogen fixation is performed by nitrogen-fixing bacteria which can reduce nitrogen gas from the air spaces of the soil to synthesize ammonia and ammonium compounds. Some nitrogen-fixing bacteria live freely in the soil. Others live in the swollen root nodules of leguminous plants, ( e.g. clover, beans, peas) Denitrification is performed by denitrifying bacteria which operate in cold, water-logged, oxygen deficient soils. These bacteria gain energy by reducing soil nitrates to nitrogen gas which then escapes into the atmosphere. Thus they reduce soil fertility

B4h Recycling Quick Quiz What is a saprophyte? An organism that feeds on dead and decaying material The conversion of nitrogen into ammonia by bacteria is called? Nitrogen fixation Denitrification is the conversion of nitrates and ammonium compounds into? Nitrogen To speed up composting conditions should be: Warm, wet and anaerobic Cold, dry and aerobic Warm, wet and aerobic Warm,dry and aerobic An earthworm that fragments leaves is an example of a ? Detritivore