nutrient cycles the sequel Flashcards
phosphorus is passed through the food web in the ____
phosphorus cycle
what do plants and animals need phosphorus to make
Plants and animals need phosphorus to make biological molecules such as phospholipids (which make
up cell membranes), DNA and ATP.
where is phosphorus found
Phosphorus is found in rocks and dissolved in the oceans in the form
of phosphate ions (P 0 43’).
where do phosphate ions dissolve
Phosphate ions dissolved in water in the soil can be assimilated (absorbed and
then used to make more com plex molecules) by plants and other producers.
what does the phosphorus cycle show
The phosphorus cycle shows how phosphorus is passed through an ecosystem.
what is step 1 of the phosphorus cycle
Phosphate ions in rocks are released
into the soil by weathering.
what is step 2 of the phosphorus cycle
Phosphate ions are taken into the plants through the roots. Mycorrhizae (see previous page) greatly increase the rate at which phosphorus can be assimilated
what is step 3 of the phosphorus cycle
Phosphate ions are transferred
through the food chain as animals
eat the plants and are in turn eaten
by other animals.
what is step 4 of the phosphorus cycle
Phosphate ions are lost from the animals in waste pro ducts.
what is step 5 of the phosphorus cycle
When plants and animals die, saprobionts are involved in breaking d own the
organic compounds, releasing phosphate ions into the soil for assimilation by plants.
These micro organisms also release the phosphate ions from urine and faeces.
what is step 6 of the phosphorus cycle
Weathering of rocks also releases phosphate ions into seas, lakes and rivers. This is taken
up by aquatic producers, such as algae, and passed along the food chain to birds.
what is step 7 of the phosphorus cycle
The waste produced by sea birds is known as guano and contains a high proportion
of phosphate ions. Guan o returns a significant amount of phosphate ions to soils
(particularly in coastal areas). It is often used as a natural fertiliser.
