Simple Sequence of

Nutrient Cycle

1. Nutrient absorption by producers

2. Producer incorporates nutrient into complex organic substance

3. Producer is eaten passing on nurtients to consumers

4. Nutrients pass along food chain as animals are eaten

5. Producers and consumers die and are broken down by saprobiotic microorganisms (decomposers) releasing nutrient in its original simple form.

1. CO₂ in the atmosphere

2. Photosynthesis

3. carbon-containing compounds in producers

4. feeding by consumers so carbon containg compounds in consumers

5. death and decay by decomposers 

1. naturally little nitrate in rivers and lakes so limiting factor for growth

2. leaching causes increase in nitrate concentration/ no longer limiting factor/ exponetial growth

3. algale bloom

4. dense surface layer prevents light from penetrating to lower depths

5. light limiting factor/ plants at lower depths die

6. Dead plants no longer limiting factor/ saprobiotic algae grow exponentially

7. Increased demand of oxygen from saprobiotic bacteria

8. Oxygen concentration decrease/ nitrate concentration increase

9. oxygen limiting factor for aerobic organisms/ organisms die

10. less competition/ anerobic organisms grow exponentially

11. decomposition of dead material/ increase in nitrates/ toxic waste

 Eutrophication question

Q. Increase in nitrate concentration in water entering lake could affect algae and fish. Explain how

Answer

1. algae bloom/ increase in algae

2. algae block light/ plants/algae die

3. decomposers/bacteria breack down dead plant material

4. bacteria/decomposers use up oxygen in respiration

5. fish die due to lack of oxygen 

 Carbon question

Q. Microorganisms make carbon in polymers in a dead worm available to cells in a leaf. Describe how.

Answer

1. microorganisms are sabriobionts/sprophytes

2. secrete enzymes (onto dead tissue)/ extracellular digestion

3. absorb products of digestion

4. respiration (by microorganisms) produces CO₂ 

5. CO₂ taken into leaves

6. through stomata

1. nitrogen in atmosphere

2. nitrogen fixation by mutalistic bacteria produces ammonium-containing molecules (e.g proteins in producers)

3.  ammonium-containing molecules in consumers by feeding and digestion

4. death and excretion/ ammonium-containing molecules in decomposers

5. ammonification by sabrobiotic microorganisms (release ammonia which forms ammonium ions in soil)

6. nitrification: carried out by nitrifing bacteria in a series of oxidation ractions releasing energy. NH₄⁺ to NO₂^- to NO₃^- .

7. denitrification: when soil becomes waterlogged increases in anaerobic denitrifing bacteria converting nirates to gaseous nitrogen.

or 

absorption by producers

1.Contain: nitrogen, phosporous and potassium (NPK)

2.Replaces nutrients lost through harvesting

Answer

1. contains other elements e.g calcium, sulphur, micronutrient (magnesium, iron)

2. adds organic matter to soil

3. May be produced as waste product on mixed farms (recycling)

4. releases nutrients slowly as decomposes

1. concentrated so; smaller quantities needed, easier storage, less transportation cost and applicayion by light machinery reducing soil compaction.

2. known nutrient content.

3. even application.