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level: 13.3 Nutrient cycles

Questions and Answers List

level questions: 13.3 Nutrient cycles

QuestionAnswer
Common features of nutrient cycles- The nutrient is taken up by producers as simple, inorganic mols - The producer converts nutrient into complex organic mols - Consumer eats producer - Passes along food chain when these animals are eaten - When producers + consumers die, their complex molecules are broken down by saprobiontic microorganisms - They release the nutrient in its simple form
What does it do- Shows how nitrogen is converted into a usable form + passed on between different living organisms - Nitrogen cycle includes food chains
Purpose of the nitrogen cycle- Plants + animals need nitrogen to make proteins + nucleic acids - The atmosphere's made up of 78% nitrogen gas, but plants + animals cant use it in that form - They need bacteria to convert it into nitrogen-containing compounds first
Key steps in the nitrogen cycle- Nitrogen fixation - Ammonification - Nitrification - Denitrification
Nitrogen fixation- The fixing of inorganic atmospheric nitrogen to ammonium ions which are converted to amino acids - Carried out by aerobic bacteria (N2 fixing bacteria) - Can be found in root nodules of leguminous plants (forms mutualistic relationship), can also be free in soil
Ammonification- The breakdown of organic compounds into ammonium ions - Carried out by saprobiontic aerobic bacteria - The waste product is ammonia this reacts with H ions from h20 to produce ammonium ions
Nitrification- The conversion of ammonium ions into nitrite then nitrate by aerobic nitrifying bacteria - These are oxidation reaction - release energy
Denitrification- Conversion of nitrates to organic atmospheric nitrogen by anaerobic denitrifying bacteria - BOOOO! farmers dont like this
Assimilated meaning- Absorbed + then used to make more complex molecules
Purpose of the phosphorous cycle- Plants + animals need phosphorous to make biological mols like phospholipids - Phosphorus is found in rocks + dissolved in the oceans in the form of phosphate ions - Phosphate ions dissolved in water in the soil can be assimilated by plants + other producers
Process of the phosphorous cycle (1)- Phosphate ions in rocks are released into the soil by weathering - Phosphate ions are taken into plants through roots
Process of the phosphorous cycle (2)- Mycorrhizae greatly increase rate at which phosphate can be assimilated - Phosphate ions are transferred through the food chain as animals eat the plants + are in turn eaten by other animals
Process of the phosphorous cycle (3)- Phosphate ions are lost form the animals in waste products - When plants + animal die, saprobionts break down organic compounds, releasing phosphate ions into the soil for assimilation by plants
Process of the phosphorous cycle (4)- These microorganisms also release the phosphate ions form urine + faeces - Weathering of rocks also releases phosphate ions into seas, lakes, rivers
Process of the phosphorous cycle (5)- This is taken up by aquatic producers, like algae, and passed along the food chain to birds - The waste produced by sea birds is known as guano + contains a high proportion of phosphate ions
Process of the phosphorous cycle (6)- Guano returns a significant amount of phosphate ions to soils - It is often used as a natural fertiliser
The importance of fungi and bacteria (mycorrhizae) in nutrient cycles- Relationship between certain types of fungi + roots of plants - Fungi act like extensions of the plant's roots system + vastly increase SA for absorption of water + minerals - The mycorrhizae acts like a sponge so holds water + minerals in the neighborhood of the roots - Plant now better at resisting drought + takes up inorganic ions more readily - The mycorrhizae plays a part in nutrient cycle by improving the uptake of relatively scarce ions like phosphates ions