Topic 5-Nutrient cycles Flashcards
What do living organisms require from their environments for growth and other processes (e.g. reproduction)?
Nutrients
What happens to the nutrients when an organism produces waste or dies and decomposes?- why
-Returned to the enviroment
-Due to them being digested (decomposed) by microorganisms
The 1._____ of this decomposition are available to 2._____ as 3._____ in the 4.____, These plants can then sustain organisms in higher trophic levels (consumers)
1.products
2.plants
3.nutrients
4.soil
Explain why nutrients are cycled in ecosystems
In stable communities:
-processes that remove nutrients (e.g. plant growth)
- are balanced by the processes that return these nutrients (e.g. decomposition of dead plants and animals)
Why do plants and animals require nitrogen?
-to produce proteins and nucleic acids (DNA and RNA)
About 78% of the atmosphere is nitrogen gas but can plants an animals access it in this form?
No
How do plants and animals take up nitrogen?
-Rely on certain bateria to convert it into a nitrogen containing compound
-Can then be taken up by plants by active transport
-Animals then consume the plants
Name the four key processes in the nitrogen cycle that are carried out by different types of bacteria
-Nitrogen fixation
-Ammonification
-Nitrification
-Denitrification
Describe the process of nitrogen fixation
-Atmospheric nitrogen gas converted into nitrogen containing compounds by nitrogen-fixing bacteria
- bacteria then converts nitrogen into ammonia, which forms ammonium ions (in solution) that can then be used by plants
Where are nitrogen-fixing bacteria found?
inside the root nodules of leguminous plants
The bacteria have a symbiotic relationship with these plants- what is meant by this?
-Mutually beneficial
-the bacteria provide the plants with nitrogen-containing compounds and the plants provide the bacteria with organic compounds such as carbohydrates
Describe what happens during ammonification
-Nitrogen compounds in waste products (e.g. urine and faeces) and dead organisms are converted into ammonia by saprobionts (a type of decomposer including some fungi and bacteria)
-This forms ammonium ions in the soil
Describe what happens during nitrification
-The ammonium ions are converted by nitrifying bacteria into (nitrites first) nitrates (nitrogen compounds), which plants can use to make amino acids
Describe what happens during denitrification
-Denitrifying bacteria use nitrates in the soil during respiration
-This produces nitrogen gas, which returns to the atmosphere
-Occurs in anaerobic conditions
Why do plants and animals require phosphorus?
In order to produce:
-DNA/RNA (nucleic acids)
-Phospholipids (for cell membranes)
-ATP + ADP
1st step of the phosphorus cycle
-Phosphorus in rocks is slowly released into the soil and into water sources in the form of phosphate ions by the process of weathering
What is whethering?
slow breaking down and erosion of rocks over time
2nd step of the phosphorus cycle
Phosphate ions are taken up from the soil by plants through their roots or absorbed from water by algae
3rd step of the phosphorus cycle
Phosphate ions are transferred to consumers during feeding
4th step of the phosphorus cycle
-Phosphate ions in waste products and dead organisms are released into the soil or water during decomposition by saprobionts
5th step of the phosphporus cycle
Phosphate ions may be taken up by producers or trapped into sediments, which turn into rock over a long period of time
What is mycorrhizae?
An association between a fungus and the roots of a plant
-The fungus grows on the plants roots
-Mutalistic/ symbiotic relationship
How do plants benefit from mycorrhizae?
-Greatly increase the total SA of the plant roots
-This increases the uptake of mineral ions by active transport and water by osmosis
-Also, hold water and mineral ions close to the roots, which increases the rate of uptake (also helps if there is a water shortage in the soil
-It increases the uptake of phosphate ions in the soil such as phosphate ions
How does the fungus benefit?
The fungus gets organic compounds such as sugar and amino acids from the plant
