Question

• Question 10

  	Which of the following statements about biological nitrogen fixation is true?
  	Answers: a. It is a strictly aerobic process b. It is a strictly anaerobic process c. It is confined to symbiotic bacteria d. It is a process carried out by bacteria, fungi and algae e. It is a process exclusive to bacteria

• Question 11

  	Which of the following statements is true in relation to anaerobic digestion?
  	Answers: a. Only animal wastes are suitable feedstocks b. It produces a biogas that cannot be upgraded to biomethane c. It can only process solid wastes d. It produces a biogas that can be upgraded to biomethane e. It can only be operated at very large scale

• Question 12

  	Methanogenic archaea can utilise:
  	Answers: a. nitrogen as substrate b. carbon dioxide and hydrogen as substrates c. amino acids as substrates d. alcohols as substrate e. glucose as substrate

• Question 13

  	The nitrogenase enzyme complex:
  	Answers: a. consists of a single protein b. cannot function in the presence of oxygen c. produces oxygen as a metabolic waste product d. can tolerate low concentrations of oxygen e. catalyzes nitrification

• Question 14

  	Anaerobic digestion of sewage sludge:
  	Answers: a. Reduces the water content of the sludge b. Can be accomplished at retention times of less than 24 hours c. Is normally carried out in CSTR reactors d. Is normally carried out in UASB reactors e. Requires biomass granulation

• Question 15

  	In relation to anaerobic wastewater treatment systems, which of the following statements is true:
  	Answers: a. They can recover 70-80% of the energy content of the wastewater b. They require aeration c. They require CSTR reactors d. They produce >0.5 kg biomass m-3 wastewater treated day-1 e. They do not require enclosure

• Question 16

  	The following is true in relation to methanogenesis:
  	Answers: a. it only occurs in ruminants b. methanogens are bacteria c. it only occurs in aquatic environments d. it requires the cooperative action of a number of different microbial trophic groups e. it requires oxygen

• Question 17

  	Which of the following statements is true in relation to microbial biofilms:
  	Answers: a. They are dependent on the presence of oxygen for growth b. They are composed of a community of microorganisms embedded in a polymer matrix c. They are composed exclusively of gram-negative bacteria d. They are normally associated with freshwater environments e. They are normally associated with anaerobic environments

• Question 18

  	Obligate hydrogen-producing acetogenic bacteria are often referred to as syntrophs becuase:
  	Answers: a. they grow in biofilms b. they are dependent on another organism for growth c. they produce methane and hydrogen as metabolic end products d. they convert acetate to carbon dioxide as a metabolic end products e. they ferment monomeric sugars

• Question 19

  	Which of the following statements is true in relation to microbial biofilms?
  	Answers: a. Biofilms are mainly associated with photosynthesis b. Biofilms are associated with the occurrence of steep chemical and pH gradients over short distances c. Biofilms are composed of aerobic bacteria d. Biofilms are generally composed of one or two species e. Biofilms are defined by competition between different species

• Question 20

  	Which of the following statements is true in relation to the carbon cycle:
  	Answers: a. Most primary production in terrestrial environments enters food webs b. Most primary production in aquatic environments occurs in sediments c. Most primary production in the ocean does not enter food webs d. Most primary production in aquatic environments occurs under anaerobic conditions e. Most primary production in the ocean enters food webs

Answer 1

Q10.

b- is correct choice

Both symbiotic and free living can do nitrogen fixation.

Its mostly anaerobic process. Enzyme nitrogenase get destroyed by presence of oxygen.

Fungi and bacteria can do nitrogen fixation.

Cyanobacteria is called blue green algae but its prokaryotic not actual algae.

Q11

d) Anaerobic digestion produces biogas, which can be upgraded to bio methane.

Q12

b) Hydrogen and Carbon dioxide as substrate to produce methane

Q13

b) Nitrogenase enzyme complex cannot function in presence of oxygen. It gets irreversibly inhibited.

Q14

a) reduces water content of sludge and its reused.

Q15

a) They can recover 70 to 80% of energy content of waste water.

Q16

d) association of arches and anaerobic bacteria

Q17

Community of microorganisms bacteria fungi protists

Q18

b) they depend on other microbes for growth.

They produce hydrogen. Hydrogen inhibit bacteria. Hydrogen consuming methanogenic bacteria live in association.

Q19

b) in hospital premises, dental surface etc