Module 6 – Ecosystems: Recycling within ecosystems

1. Module 6 – Ecosystems: Recycling within ecosystems Equipment: Spec: 6.3.1: (c) recycling within ecosystems To include the role of decomposers and the roles of microorganisms in recycling nitrogen within ecosystems (including Nitrosomonas, Nitrobacter, Azotobacterand Rhizobium) AND the importance of the carbon cycle to include the role of organisms (decomposition, respiration and photosynthesis) and physical and chemical effects in the cycling of carbon within ecosystems. • Pg.276-278 Handouts:

5. Recycling within ecosystems L.O. to describe the roles of microorganisms in the recycling of N & C in ecosystems. Module 6 Tuesday, 30 January 2018 Tasks STARTER Recycling Nitrogen cycle Carbon cycle Exam practise Starter • Key terms • Recycling • Saprotrophs • Nitrogen • Ammonification • Nitrogen fixation • Nitrification • Denitrification • Chemoautotrophic bacteria • Carbon Green pen of assessment.

6. Recycling within ecosystems L.O. to describe the roles of microorganisms in the recycling of N & C in ecosystems. Module 6 Tuesday, 30 January 2018 Tasks STARTER Recycling Nitrogen cycle Carbon cycle Exam practise Recycling • Animals secure their N (and all other) compounds from plants [or animals that have fed on plants = “assimilation“]. • i.e. animals digest, absorb and assimilate forms of nitrogen from their food. • Key terms • Recycling • Saprotrophs • Nitrogen • Ammonification • Nitrogen fixation • Nitrification • Denitrification • Chemoautotrophic bacteria • Carbon Bacteria & fungi (decomposers) are known as “saprotrophs” as they: Secrete enzymes onto dead & waste material Enzymes digest the material into small molecules, which are absorbed into the decomposer. Now, the molecules are either stored or respired to release E.

7. Recycling within ecosystems L.O. to describe the roles of microorganisms in the recycling of N & C in ecosystems. Module 6 Tuesday, 30 January 2018 Tasks STARTER Recycling Nitrogen cycle Carbon cycle Exam practise Nitrogen cycle • All life requires nitrogen-compounds, e.g., proteins and nucleic acids. • Air, which is 79% nitrogen gas (N2), is the major reservoir of nitrogen. • But most organisms cannot use nitrogen in this form as nitrogen gas is INERT. • Key terms • Recycling • Saprotrophs • Nitrogen • Ammonification • Nitrogen fixation • Nitrification • Denitrification • Chemoautotrophic bacteria • Carbon • Four biological processes participate in the cycling of nitrogen through the biosphere: • nitrogen fixation • decomposition • nitrification • denitrification

8. N in animals decomposition NH+4 excretion decomposition N in excretory products Nitrogen fixation Feeding/assimilation Nitrification decomposition NO-2 N2 N in plants denitrification Nitrification Absorption and assimilation NO-3

9. Interactive overview of N cycle:http://www.pbslearningmedia.org/asset/lsps07_int_nitrogen/ Nitrogen cycle

10. Recycling within ecosystems L.O. to describe the roles of microorganisms in the recycling of N & C in ecosystems. Module 6 Tuesday, 30 January 2018 Tasks STARTER Recycling Nitrogen cycle Carbon cycle Exam practise Nitrogen fixation • The nitrogen molecule (N2) is quite inert. To break it apart so that its atoms can combine with other atoms requires the input of substantial amounts of energy. • 3 processes are responsible for most of the nitrogen fixation in the biosphere: • Key terms • Recycling • Saprotrophs • Nitrogen • Ammonification • Nitrogen fixation • Nitrification • Denitrification • Chemoautotrophic bacteria • Carbon Biological fixation – by certain microbes. Atmospheric fixation – by lightning. Industrial fixation – the Haber process

11. Recycling within ecosystems L.O. to describe the roles of microorganisms in the recycling of N & C in ecosystems. Module 6 Tuesday, 30 January 2018 Tasks STARTER Recycling Nitrogen cycle Carbon cycle Exam practise Nitrogen fixation • Key terms • Recycling • Saprotrophs • Nitrogen • Ammonification • Nitrogen fixation • Nitrification • Denitrification • Chemoautotrophic bacteria • Carbon Free-living bacteria such as Azotobacter Symbiotic (mutualistic) bacteria Rhizobium in root nodules of legumes Root nodules on clover plant Rhizobium contains an enzyme called nitrogenase that converts nitrogen and hydrogen to ammonia.

12. Recycling within ecosystems L.O. to describe the roles of microorganisms in the recycling of N & C in ecosystems. Module 6 Tuesday, 30 January 2018 Tasks STARTER Recycling Nitrogen cycle Carbon cycle Exam practise Decomposition • The proteins made by plants enter and pass through food webs just as carbohydrates do. • At each trophic level, their metabolism produces organic N compounds that return to the environment (i.e. Excretions). • The final beneficiaries of these materials are microorganisms of decay. • They break down the molecules in excretions and dead organisms into ammonia. • Key terms • Recycling • Saprotrophs • Nitrogen • Ammonification • Nitrogen fixation • Nitrification • Denitrification • Chemoautotrophic bacteria • Carbon Note: Decomposers are SO useful as they release these “trapped nutrients” from decaying organisms.

13. Recycling within ecosystems L.O. to describe the roles of microorganisms in the recycling of N & C in ecosystems. Module 6 Tuesday, 30 January 2018 Tasks STARTER Recycling Nitrogen cycle Carbon cycle Exam practise Ammonification & Nitrification • Key terms • Recycling • Saprotrophs • Nitrogen • Ammonification • Nitrogen fixation • Nitrification • Denitrification • Chemoautotrophic bacteria • Carbon • Ammonia (NH3) can be taken up directly by plants - usually through their roots. • However, most of the ammonia produced by decay is converted into nitrates. • This is accomplished in 2steps: These two groups or autotrophic bacteria are called “nitrifying bacteria.“ Bacteria of the genus Nitrosomonas oxidise NH3 to nitrites (NO2-). Bacteria of the genus Nitrobacter oxidise the nitrites to nitrates (NO3-).

14. Recycling within ecosystems L.O. to describe the roles of microorganisms in the recycling of N & C in ecosystems. Module 6 Tuesday, 30 January 2018 Tasks STARTER Recycling Nitrogen cycle Carbon cycle Exam practise Denitrification • Denitrification reduces nitrates (NO3-) to nitrogen gas (N2), thus replenishing the atmosphere. • Thus itcloses the Nitrogen cycle. • Key terms • Recycling • Saprotrophs • Nitrogen • Ammonification • Nitrogen fixation • Nitrification • Denitrification • Chemoautotrophic bacteria • Carbon Link to respiration: Once again, bacteria such as Pseudomonas are the agents. They live deep in soil and in aquatic sediments where conditions are anaerobic. They use nitrates as an alternative to oxygen for the final electron acceptor in their respiration.

15. Quick Quiz /5 Write the numbers:

16. Q.1 Which process describes the two step oxidation of ammonia to nitrate? • Denitrification • Nitrification • Nitrogen fixation

17. Q.2 Which bacterial species is responsible for denitrification? • Rhizobium • Nitrosomonas • Pseudomonas

18. Q.3 Which process describes the conversion of nitrogen gas to ammonia • Denitrification • Nitrification • Nitrogen fixation

19. Q.4 Which process describes the conversion of nitrogen containing compounds in plants to ammonia • Denitrification • Assimilation • Decomposition

20. Q.5 Which of these bacterial species is responsible for nitrification? a) Nitrosomonas • Pseudomonas • Rhizobium

21. Answers

22. Q.1 Which process describes the two step oxidation of ammonia to nitrate? • Denitrification • Nitrification • Nitrogen fixation b)

23. Q.2 Which bacterial species is responsible for denitrification? • Rhizobium • Nitrosomonas • Pseudomonas c)

24. Q.3 Which process describes the conversion of nitrogen gas to ammonia • Denitrification • Nitrification • Nitrogen fixation c)

25. Q.4 Which process describes the conversion of nitrogen containing compounds in plants to ammonia • Denitrification • Assimilation • Decomposition c)

26. Q.5 Which of these bacterial species is responsible for nitrification? a) Nitrosomonas • Pseudomonas • Rhizobium a)

27. Recycling within ecosystems L.O. to describe the roles of microorganisms in the recycling of N & C in ecosystems. Module 6 Tuesday, 30 January 2018 The C cycle – Nathaniel Manninghttps://www.youtube.com/watch?v=A4cPmHGegKI Tasks STARTER Recycling Nitrogen cycle Carbon cycle Exam practise Carbon cycle • Key terms • Recycling • Saprotrophs • Nitrogen • Ammonification • Nitrogen fixation • Nitrification • Denitrification • Chemoautotrophic bacteria • Carbon • Identify which processes: • Release carbon • Absorb carbon Ex: What role do humans play in the C cyle?

28. Recycling within ecosystems L.O. to describe the roles of microorganisms in the recycling of N & C in ecosystems. Module 6 Tuesday, 30 January 2018 Complete the exam practice provided. Tasks STARTER Recycling Nitrogen cycle Carbon cycle Exam practise Exam practise • Key terms • Recycling • Saprotrophs • Nitrogen • Ammonification • Nitrogen fixation • Nitrification • Denitrification • Chemoautotrophic bacteria • Carbon