Topic 5 - Energies In Ecosystems

• air is 78% nitrogen, however plants and animals cannot obtain nitrogen through gas exchange. • Nitrogen gas (N,) contains a triple bond. NEN • Microorganisms are needed to convert nitrogen gas into nitrogen containing substances that plants and animals can absorb.

Protiens, ATP and nucleic acids

I. Saprobiotic nutrition and microbes 2. Ammonification 3. Nitrification 4. Nitrogen fixation 5. Denitrification

When gas can be fixed into ammonia via haber process. Used in production of fertilisers. Small amount of nitrogen is fixed to nitrate by lightening.

They reduce nitorgen gas to ammonia which they then use to manufacture amino acid nitrogen rich compounds that are released when they die.

Free to live in water or soil. Or They may live in colonies inside cells of root nodules of leguminous plants

In return for sugars from the plant, the bacteria fixed nitrogen is used by for plant for growth. Nitrogen in plant protein is passed into animals through food chain

When living organisms excrete waste or die their nitrogen is returned to soil in form of ammonium compounds by saprobiotic microorganisms (bacteria and fungi)

They break down proteins in denitriles to form ammonium ions (deanimation) This is where nitrogen returns to the non living components of an ecosystem

When plants can only take up nitrogen in form of nitrate. Ammonium compounds are oxidised into nitrates by nitrifying bacteria in two stages.

First forming nitrite ions (nitrosomotias) Then forming nitrate ions (nitrobacters)

Oxidation reaction so releases energy. These are chemosynthetic bacteria which means they use the energy released by nitrification to live. Nitrifying bacteria require oxygen to carry out conversions so soil needs many air space

Ploughing and good drainage

A microbially facilitated process of nitrate production (performed by a large group of heterotrophic anaerobic bacteria) This produces molecular nitrogen N2 This respiratory process reduces oxidised forms of nitrogen in response to oxidation of an electro donor such as organic matter

Most least thermodynamically favourable includes nitrate nitrite nitrogen oxide nitrous oxide and dinitrogen

It can lower the leaching of nitrate to ground water Denitrrification allows for the production of nitrous oxide which is a greenhouse gas.

• DNA/RNA • АТР • Phospholipid bilayer It is therefore an essential element for life

Phospherous cycle This cycle is different to the carbon and nitrogen, in that phosphorus is not found as a gas and therefore not in the atmosphere. Instead it is mainly found as a phosphate ion, in mineral form in sedimentary rocks.

are fungal associations between plant roots and beneficial fungi

• The fungi increase the surface area for water and mineral absorption • The mycorrhizae acts like a sponge so holds water and minerals around the roots. • This makes plants more drought resistant and able to take up more inorganic ions. Their part in the nutrient cycles is therefore improving the uptake of relatively scarce ions, such as phosphate ions. This is a mutualistic relationship.

Phosphate found in rocks. Phosphate salts are released from rocks through weathering usually dissolve in soil water and will be absorbed by plants.

Animals absorb phosphates by eating plants or eating other animals. When animals and plants die, phsophates retyrn to soil or ocean by decompositon. Then phosphates end up in sediments rock formations again remaining there for millions of years.

Increased use of fertilisers increases phospherous runoff into waterways and contributes to eutrophication

They act like extensions of the plants roof system and increase total surface area for the absorption of water and minerals They act like a sponge so hold water and minerals around the root complex enabling maximum water uptake