Phosphorus Cycle

Question 1

Why do plants and animals need phosphorus?

Answer 1

Production of phospholipids
Nucleic acids
AATP

Question 2

What happens to phosphorus in rocks?

Answer 2

Phosphorus in rocks is released into the soil and into water sources in the form of phosphate ions due to weathering

Question 3

How are phosphate ions taken up?

Answer 3

From the soil by plants or absorbed from water by algae

Question 4

What happens to phosphate ions during feeding?

Answer 4

They are transferred to consumers

Question 5

What happens to phosphate ions in waste products and dead organisms?

Answer 5

Released into the soil or water during decomposition by saprobionts
Saprobionts/decomposers break down the molecules in dead organisms to release phosphate ions into the soil

Question 6

Sediments?

Answer 6

Phosphate may be trapped in sediments that may turn into phosphorous-containing rock once again

Question 7

Describe how phosphorus gets recycled back into the ecosystem (3 marks)

Answer 7

Animals produce faeces/animals die
The phosphorous containing substances in their faeces or tissues are digested by sapriobiotic bacteria
This releases phosphate ions
Phosphate ions can then be taken up again by plants

Question 8

Possible sources of phosphate?

Answer 8

Fertilisers
Detergent
Manure

Question 9

Explain why phosphates are essential for plants to grow (3 marks)

Answer 9

The production of phospholipids.- found in cell membranes
Production of RNA/DNA
The synthesis of ATP

Question 10

How do animals obtain phosphorus from their plant food?

Answer 10

Absorbing phosphate ions directly from their food
Digesting biological molecules in their food such as nucleic acids
Digesting food into smaller phosphate-containing molecules e.g. nucleotides which can then be absorbed

Question 11

3 ways in which phosphorous is introduced into soil and water in oceans, lakes and rivers

Answer 11

Weathering of sedimentary rocks
Excretion by animals
Erosion of dead animal materials e.g. bones/shells