Phosphorus cycle

What is Phosphorous used for in organisms?

• DNA

• RNA 

• ATP

• Phospholipid bilayer

Explain the role of saprobionts in recycling chemical elements

• Decompose organic compounds (e.g proteins, urea, DNA in dead matter, organic waste)

• By secreting enzymes for extracellular digestion

• Absorb soluble needed nutrients and release mineral ions - phosphate ions

What are Mycorrhizae?

Fungal associations between plant roots and beneficial fungi

Why are Mycorrhizae beneficial for plant growth?

1. The fungi increase the SA for water and mineral absorption

2. The mycorrhizae acts like a sponge so holds water and minerals around the roots

3. This makes plants more drought resistant and able to take up more inorganic ions

Their part in the nutrient cycles is therefore improving the uptake of relatively scarce ions, such as phosphate ions → this is a mutualistic relationship; plants benefit from improved water and inorganic ion uptake and fungi receives organic compounds (sugars and amino acids) from plants

Draw the Phosphrorus Cycle

Explain the stages of the Phosphorous cycle

1. Phosphate ions in rocks released into soils and oceans by erosion

2. Phosphate ions taken up by producers and incorporated into their biomass → rate of absorption increased by mycorrhizae 

3. Phosphate ions transferred through the food chain 

4. Some phosphate ions lost from animals in excretion 

5. Saprobionts decompose organic compounds eg. DNA in dead matter/ organic waste releasing phosphate ions