1. Cycles of Life Life and Death, Nutrient Cycles

2. Nutrient Cycles Why do the nutrients on the Earth need to be cycled? – The Earth is considered a closed system. – This means that there is little or no input of new materials from outside the system. Organics = H and C, often O and N (proteins, fats, sugars) Inorganics – not containing C and H – Nutrients can be in the biotic environment or abiotic environment.

3. The Carbon Cycle photosynthesis Plants make carbohydrates through a process known as photosynthesis. – 6CO 2 + 6H 2 O + E  C 6 H 12 O 6 + 6O 2 – Capture of carbon from atmosphere cellular respiration Carbon is returned to the atmosphere via cellular respiration. – C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O + E

4. The Nitrogen Cycle Nitrogen is also very important and it will also circulate between the biotic and abiotic parts of the environment. – Proteins and DNA Fertilizers contain N, P and K to facilitate growth If there is no fertilizer then how does the plant acquire N?

5. Agriculture and Nutrient Cycles Phosphate Accumulation 1.Algae growth = algal bloom 2.Bacteria break down algae and use oxygen to do so 3.Fish and animals die 4.Problems become worse