Energy Transfers in and Between Organisms: Nutrient Cycles - Phosphorus Cycle Flashcards
1
Q
Why do organisms need phosphorus?
A
- To make phospholipids (for cell membranes)
- To make DNA and RNA
- To make ATP
2
Q
Where does phosphorus originate from?
A
- Phosphorus is found in rocks
- Phosphorus dissolves in the oceans to form phosphate ions (PO4 ^3-)
- Phosphate ions may remain in oceans/lakes/rivers or be incorporated in soil
3
Q
Draw the entire phosphorus cycle
A
4
Q
Describe the direction of the phosphorus cycle that occurs at sea
A
- Rock → Seas/lakes/rivers → Algae and other primary producers → Fish → Birds → Guano → Soil
5
Q
Describe the direction of the phosphorus cycle that occurs in the soil
A
- Rock → Soil → Plants → Animals → Decaying organisms OR faeces and urine → Soil
6
Q
Explain the phosphorus cycle that occurs on land
A
- Phosphate ions in rocks are released into the soil by weathering
- Phosphate ions are taken into the plants through the roots. Mycorrhizae increase the rate at which phosphorus can be assimilated
- Phosphate ions are transferred through the food chain from plants to animals
- Phosphate ions are lost from animals in waste products
- Saprobionts break down organic compounds from dead plants and animals, releasing phosphate ions into the soil for assimilation by plants. Saprobionts also release phosphate ions from urine and faeces
7
Q
Explain the phosphorus cycle that occurs in the sea
A
- Weathering of rocks releases ions into seas, lakes and rivers
- Phosphate ions are taken up by aquatic producers (e.g algae) and passed along the food chain to the birds
- Waste produced by birds is called guano and contains a high proportion of phosphate ions. Guano returns a large amount of phosphate ions to soils and is used as a fertiliser
8
Q
Define the term assimilation
A
- Assimilation is the movement of digested food molecules into the cells of the body where they are used
9
Q
Define the term weathering
A
- Weathering is the breaking down or dissolving of rocks
