3.2 Microorganisms & Nutrient Cycling
In brief:Microorganisms play essential roles in nutrient cycling, industry, and human health. The carbon and nitrogen cycles are biogeochemical cycles critical for life.
Structure of a typical prokaryotic (bacterial) cell
Wikimedia Commons (CC)
The body's immune response to microorganisms
Wikimedia Commons (CC)
Key Points
- 1Bacterial cell: prokaryotic - cell wall, cell membrane, cytoplasm, ribosomes, circular DNA, plasmids.
- 2Rhizopus: a fungus with hyphae. Eukaryotic. Saprophytic nutrition.
- 3Nutrition types: autotrophic, heterotrophic, saprophytic, parasitic.
- 4Factors affecting microbial growth: pH, nutrients, water, temperature, antibacterial chemicals.
- 5Growth curve: lag → log (exponential) → stationary → decline/death → survival.
- 6Microbiome: community of microorganisms (gut helps digestion, immunity, metabolic health).
- 7Carbon cycle: photosynthesis, respiration, decomposition, fossil fuels, carbon sinks.
- 8Nitrogen cycle: nitrogen fixation, nitrification, decomposition, denitrification.
- 9Climate change: linked to atmospheric CO₂ and methane increases.
Learning Outcomes
- Distinguish between bacteria and fungi in terms of structure, nutrition, and cellular nature
- Investigate factors affecting the growth of microorganisms, use primary and secondary data to support conclusions
- Discuss the importance of microorganisms in industries
- Outline the concept of a microbiome; explore the role of microbiomes in promoting human health and nutrient cycling in soils
- Model the carbon cycle with reference to the roles of photosynthesis, respiration, decomposers, fossil fuels and carbon sinks
- Model the nitrogen cycle with reference to nitrogen fixation, nitrification, decomposition, denitrification
- Evaluate ethical and sustainability issues associated with the cycling of nutrients
- Discuss the link between atmospheric carbon dioxide, methane and climate change; evaluate biological strategies to reduce atmospheric levels of these gases