Nutrient cycles Flashcards
What are saprobionts?
A type of microorganism
What are saprobionts a type of and why is this the case?
Decomposers
They feed on the remains of dead plants and animals and on their waste products, breaking them down
What can saprobionts also do?
Extracellular digestion
What is extracellular digestion?
Saprobionts secrete enzymes and digest their food externally and then absorb the nutrients they need
What is saprobiotic nutrition?
Obtaining nutrients from dead organic matter and animal waste using extracellular digestion
What is a mycorrhizae relationship?
A symbiotic relationship between fungi and the roots of plants
What are hyphae?
Long, thin strands made up of fungi connected to the plant’s roots
What is the purpose of hyphae?
To significantly increase surface area of the plant’s root system, helping the plant to absorb ions from the soil that are usually scarce
What are the 4 parts of the nitrogen cycle?
Nitrogen fixation
Ammonification
Nitrification
Denitrification
What percentage of the atmosphere is made up of nitrogen?
78%
What is nitrogen fixation?
When nitrogen gas from the atmosphere is turned into useful nitrogen-containing compounds
What carries out biological nitrogen fixation?
nitrogen-fixing bacteria such as Rhizobium
What does Rhizobium do?
Turn nitrogen into ammonia which goes on to form ammonia ions in solution that can be used by plants
Where are Rhizobium found?
On root nodules of leguminous plants
What do Rhizobium form with the plant? What does this entail?
A mutualistic relationship
They provide the plant with nitrogen-containing compounds and the plant provides them with carbohydrates
What is a mutualistic relationship?
Type of symbiotic relationship where both species benefit
What is ammonification?
When nitrogen compounds from dead organisms are turned into ammonia by saprobionts, which goes on to form ammonium ions.
What, other than dead organisms, contain nitrogen compounds?
Animal urine and faeces
What is nitrification?
When ammonium ions in the soil are changed into nitrogen compounds that can then be used by plants
What is the first stage of nitrification?
Nitrifying bacteria called nitrosomnas change ammonium ions into nitrites
What is the second stage of nitrification?
Other nitrifying bacteria called nitrobacter change the nitrites into nitrates
What is denitrification?
When nitrates in the soil are converted into nitrogen gas by denitrifying bacteria.
How do denitrifying bacteria carry out their job? What conditions are required?
Use nitrates in the soil to carry out respiration and produce nitrogen gas
Anaerobic conditions eg. waterlogged field
What are other ways that nitrogen can enter an ecosystem?
Lightning
Artificial fertilisers
Why is phosphorus important in organisms?
To make biological molecules;
- Phospholipids
- DNA
- ATP
Where is phosphorus found?
in rocks
Where does phosphorus go after the rocks?
Dissolves into the oceans in the form of phosphorus ions
How are phosphate ions from rocks released?
Weathering
How does weathering occur?
by mechanical, chemical and biological processes
How do plants take up phosphate ions?
By assimilation through the roots
What is there on the roots of plants which greatly increase the intake of the phosphorus in plants?
Mycorrhizae
How is phosphorus transferred through the food chain?
When animals eat the plants and then in turn are eaten by other animals
How are phosphate ions lost from the animals?
Waste products eg. excretion
What happens to the phosphorus ions when the animals and plants die?
Saprobionts break the organic compounds and release the phosphate ions into the soil so the plants can assimilate it
How can aquatic producers take up phosphate ions?
When the rocks weather, some ions will enter rivers, lakes and oceans
How do birds get phosphate ions?
They eat the aquatic producers who have taken up the phosphate
What is guano and how is it involved in the phosphorus cycle?
The waste product of birds which contains phosphate ions that get returned back to the rocks and soil
How does phosphorus get back into the rocks and mountains?
When fish die, their remains lie on the bottom of the ocean floor and eventually become part of the ground and this will eventually rise up to form the rocks and mountains
What is a use of guano?
Natural fertiliser
