Presentation on theme: "1.11 The Phosphorus Cycle (Sec 4.5 pg 98-100). Phosphorus (P) is an essential biological molecule (Figs 1&2 p.98) – it’s used for making DNA, proteins."— Presentation transcript:
Elements cycled on a global scale that we’ve examined so far (oxygen, carbon, nitrogen) commonly exist in gas form, but P doesn’t – this is something unique about the P cycle.
All P originates from the weathering of sedimentary and metamorphic bedrock in the Earth’s crust – Phosphate ions (PO 4 ) are dissolved from rock into soil or water through weathering. P is then absorbed by producers (plants), who absorb phosphates from the soil.
There are two cycles associated with P (Fig 3 p.99, and Data Pages): – Short cycle = takes less time for the P to cycle. Organisms die releasing P into the soil and water. Producers absorb P from the soil. Consumers eat producers (consumers get their P from producers).
o Long Cycle = takes thousands / millions of years (a very long cycle) i.Organism die - elements (P) from body deposited on the ocean floor. ii.Ocean floor forms sedimentary rock. iii.Rock is eventually exposed to weather and the P in the rock dissolves. iv.The water and P (phosphate) are absorbed by a plant. v.Plants (producers) eaten by consumers.
RANDOM FACTS TIME!!! What organism currently holds the title for the largest organism on Earth??? C’mon, what d’ya think?? VIDEO: http://www.youtube.com/watch?v=vWAA-SrrFUQ
Certain species of fungi live in association with plant roots (these fungi have a symbiotic relationship with the plants) – these fungi are called mycorrhizae (Fig.4 p.99). The fungi increase the availability of phosphates for the host plants, and the plants provide the fungi with carbohydrates from photosynthesis. In essence, they ‘feed’ each other!
Mycorrhizae are extremely important to plants – it is estimated that ~ 80% of plant species associate with mycorrhizal fungi! VIDEO: http://www.youtube.com/watch?v=AlunzuBdOAw&list=PL2SBAFWHOIW2Jh_go-Hfe6bHnW5ibCggp
Human activities can add P to ecosystems. Examples include: farmers adding commercially- produced fertilizers (typically contain N, P, and potassium); animal manure contains P and is used as a fertilizer; sewage and industrial outflows add phosphates to water systems (often in a ‘bad’ way – pollution).