Question
Substances found in dead leaves contain carbon.
Describe how microorganisms make this carbon available to plants
How have human activities lead to global warming
Why does growing crops for biofuel lead to decease in biodiversity?
Why do biofuels lead to a net reduction in carbon dioxide production
Perfect answer
1) Saprobiotic bacteria do extracellular digestion (secrete enzymes)
2) Starch converted to glucose by amylase enzyme
3) Glucose absorbed
4) Glucose used in aerobic respiration
5) Carbon dioxide released
6) Carbon dioxide taken in by plants for photosynthesis
1) Carbon dioxide is a greenhouse gas
2) Deforestation leads to reduced photosynthesis, so reduced carbon dioxide uptake from atmosphere
3) Combustion of fossil fuels leads to carbon dioxide production
4) Methane is a greenhouse gas
5) Methane is produced from cattle or rice growing
6) Increased levels of greenhouse gases lead to global warming
1) Crop is a monoculture, so lowers biodiversity
2) Reduced variety of habitats for animals
3) Reduced variety of food for animals
1) Crops take in carbon dioxide when they photosynthesise
2) More carbon dioxide is taken in than produced when the crops are burnt
Make sure you know the names of processes and bacteria
Reaction
1) Proteins to amino acids
Type of bacteria
Saprobiotic
2) Amino acids to ammonia Ammonifying
3) Ammonium to nitrites
4) Nitrites to nitrates
Nitrogen to ammonia 
Nitrates to nitrogen
Question

Nitrifying
Nitrifying
Nitrogen fixing (in root nodules or free living in soil)
Denitrifying
Describe the role of microorganisms in producing nitrates for plants (from the remains of dead organisms)
Explain how an increase in nitrate ions in ponds / rivers could affect fish
Name of process
Digestion (Hydrolysis reaction)
Ammonification
Nitrification (oxidisation reaction)
Nitrification (oxidisation reaction)
Nitrogen fixing
Denitrification
Perfect Answer
1) Protein converted into amino acids by saprobiotic bacteria
2) Amino acids converted to ammonia by saprobiotic bacteria
3) Ammonium ions into nitrites by nitrifying bacteria
4) Nitrites into nitrates by nitrifying bacteria
If ‘from dead organisms’ is not mentioned in the question then you can add:
5) Nitrogen fixing bacteria convert nitrogen to ammonia
1) Increased growth of algae leading to algal bloom
2) Algae blocks light leading to lack of photosynthesis of plants and plant death
3) Saprobiotic bacteria break down dead plants
4) Bacteria use up oxygen in aerobic respiration
5) Fish die due to lack of oxygen