Microbes in biogas production — practice questions
7 questions in the bank on this idea. Below are 7 of them, exactly as they appear in a test.
Which group of microbes is primarily responsible for methane production in biogas plants?
- A. Mycorrhizal fungi
- B. Cyanobacteria
- C. Lactic acid bacteria
- D. Methanogens
Why are anaerobic conditions maintained in a biogas digester?
- A. Methane is produced only by photosynthesis
- B. Methanogens function best without oxygen
- C. Oxygen is needed to form dung slurry
- D. Aerobic bacteria alone make methane
Why is cattle dung a useful starting material for many biogas plants?
- A. It is composed only of methane
- B. It contains no microorganisms
- C. It supplies organics plus methanogens
- D. It prevents all anaerobic decomposition
Which gas is the major combustible component of biogas?
- A. Methane
- B. Oxygen
- C. Nitrogen
- D. Hydrogen chloride
A biogas digester receives plenty of organic slurry, but oxygen continuously leaks into the chamber. What is most likely to happen?
- A. The slurry becomes sterile immediately
- B. Methane production necessarily doubles
- C. Only photosynthesis increases
- D. Methane production decreases
Why are methanogens also found in the rumen of cattle?
- A. They aid anaerobic breakdown in the rumen
- B. They carry out oxygenic photosynthesis
- C. They fix atmospheric nitrogen specifically for the grazing animal
- D. They digest cellulose using sunlight
A digester is functioning normally, but the feed is suddenly replaced with material containing very little biodegradable organic matter. What is the most likely effect?
- A. Biogas output rises because microbes need less food
- B. Biogas falls as usable substrate declines
- C. Methane production becomes independent of microbes
- D. Oxygen becomes the main fuel produced
Want to know which of these you would get wrong?
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