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Microbial Metabolism

Description: Microbiology GATE Life Sciences Biotechnology Microbial Metabolism
Number of Questions: 15
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Tags: Microbiology GATE Life Sciences Biotechnology Microbial Metabolism
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Which of the following statements is/are TRUE regarding bacterial photosynthesis?

  1. Bacteriochlorophyll absorbs in the range of 650-750nm.
  2. Water acts as photosynthetic electron donor.
  3. Noncyclic photophosphorylation is absent. Select the correct answer.
  1. 1 only

  2. 2 only

  3. 3 only

  4. 1 and 2 only

  5. 2 and 3 only


Correct Option: C
Explanation:

Noncyclic photophosphorylation is absent in bacterial photosynthesis.

Lithotrophs are categorized into different physiological groups based on their inorganic substrate for energy production and growth. Which of the following ‘physiological group: energy source’ pair are not correct?

  1. Hydrogen bacteria: H2
  2. Methanogens: CH4
  3. Carboxydobacteria: CO
  4. Iron bacteria: Fe+++
  1. 1 and 2 only

  2. 1 and 3 only

  3. 2 and 3 only

  4. 2 and 4 only

  5. 3 and 4 only


Correct Option: D
Explanation:

The methanogens oxidizes H2 as a sole source of energy while transferring the electrons from H2 to CO2 in its reduction to methane. Iron bacteria oxidize Fe++ as energy source to Fe+++.

Which of the following statements is/are FALSE regarding Entner–Doudoroff pathway?

  1. It is an alternate series of reactions that catabolize glucose to pyruvate.
  2. It occurs both in prokaryotes as well as eukaryotes.
  3. It has a net yield of 2 ATP for every glucose molecule metabolized. Select the correct answer.
  1. 1 only

  2. 2 only

  3. 3 only

  4. 1 and 2 only

  5. 2 and 3 only


Correct Option: E
Explanation:

Entner–Doudoroff pathway occurs only in prokaryotes. Entner–Doudoroff pathway has a net yield of 1 ATP, 1 NADH and 1 NADPH for every glucose molecule metabolized.

Which of the following is an example of gram-positive bacteria having ability to oxidize glucose by Entner–Doudoroff pathway?

  1. Bacillus subtilis

  2. Enterococcus faecalis

  3. Escherichia coli

  4. Xanthomonas campestris

  5. Zymomonas mobilis


Correct Option: B
Explanation:

Very few gram-positive bacteria have ability to oxidize glucose by Entner–Doudoroff pathway. Enterococcus faecalis is an example of gram-positive bacteria having ability to oxidize glucose by Entner–Doudoroff pathway.

Entner-Doudoroff pathway was first discovered by Michael Doudoroff and Nathan Entner in _________.

  1. Azotobacter beijerinckii

  2. Enterococcus faecalis

  3. Pseudomonas Saccharophila

  4. Rhizobium japonicum

  5. Zymomonas mobilis


Correct Option: C
Explanation:

Entner-Doudoroff pathway was first reported by Michael Doudoroff and Nathan Entner in Pseudomonas Saccharophila.

Which of the following is/are non-protein electrons carrier molecule(s) in electron transport chains?

  1. NADH-Q reductase
  2. Cytochromes
  3. Ubiquinones
  1. Only 1

  2. Only 2

  3. Only 3

  4. Both 1 and 2

  5. Both 2 and 3


Correct Option: C
Explanation:

Ubiquinones (also known as Coenzyme Q) are non-protein electron carriers located in the inner mitochondrial membrane.

Match the column – I (Microorganism) with column – II (Physiological group) and select the correct option.

 
Column – I Column – II
P. Gallionella 1. Nitrifying bacteria
Q. Alcaligenes 2. Hydrogen bacteria
R. Rhodospirillum 3. Carboxydobacteria
S. Nitrobacter 4. Iron bacteria
  1. P - 1, Q - 2, R - 3, S - 4

  2. P - 2, Q - 1, R - 4, S - 3

  3. P - 3, Q - 2, R - 1, S - 4

  4. P - 4, Q - 2, R - 3, S - 1

  5. P - 4, Q - 3, R - 2, S - 1


Correct Option: D
Explanation:

Gallionella oxidize Fe++ as a source of energy for lithoautotrophic growth. Alcaligenes are hydrogen bacteria, i.e., they oxidize H2 as an energy source. Rhodospirillum are carboxydobacteria, i.e., they oxidize CO to CO2 using an enzyme carbon monoxide dehydrogenase. Nitrobacter oxidizes NO2 to NO3.

Match the column – I (Type of organism) with column – II (Site of photosynthesis) and select the correct option.

 
Column – I Column – II
A. Cyanobacteria 1. Chromatophores
B. Green sulphur bacteria 2. Chlorosomes
C. Purple bacteria 3. Thylakoids
  1. A - 1, B - 2, C - 3

  2. A - 1, B - 3, C - 2

  3. A - 2, B - 1, C - 3

  4. A - 2, B - 3, C - 1

  5. A - 3, B - 2, C - 1


Correct Option: E
Explanation:

Site of photosynthesis in cyanobacteria is thylakoids. Site of photosynthesis in green sulphur bacteria is chlorosomes. Site of photosynthesis in purple bacteria is chromatophores.

ASSERTION (A): During aerobic respiration, lesser number of ATPs is produced in eukaryotes than in prokaryotes. REASON (R): In eukaryotes some energy is lost when electrons are shuttled across the mitochondrial membranes that separate glycolysis (in cytoplasm) from the electron transport chain.

In the following question there are two statements, Assertion (A) and Reason (R), consider both the statements independently and mark your answers as under:
1. If A and R both are correct and R is correct explanation of A.
2. If A and R both are correct and R is not correct explanation of A.
3. If A is correct and R is incorrect.
4. If A is incorrect and R is correct.
5. If A and R both are incorrect.

  1. 1

  2. 2

  3. 3

  4. 4

  5. 5


Correct Option: A
Explanation:

Assertion as well as reason statements are correct and R is correct explanation of A. During aerobic respiration, lesser number of ATPs is produced in eukaryotes (34 molecules of ATP) than in prokaryotes (38 molecules of ATP). This is because of the reason that, in eukaryotes, some energy is lost when electrons are shuttled across the mitochondrial membranes that separate glycolysis (in cytoplasm) from the electron transport chain. No such separate mechanism exists in prokaryotes.

Which of the following is a pair of dissimilative sulfur reducers?

  1. Archaeoglobus and Desulfobulbus

  2. Campylobacter and Desulfuromonas

  3. Desulfococcus and Desulfobacter

  4. Archaeoglobus and Desulfuromonas

  5. Campylobacter and Desulfobacter


Correct Option: B
Explanation:

In dissimilative sulfur reduction, elemental sulfur is reduced to hydrogen sulfide. Dissimilative sulfur reducers reduce elemental sulfur to hydrogen sulfide. Campylobacter and Desulfuromonas are dissimilative sulfur reducers.

Which of the following is a set of microbes yielding lactic acid as fermentation end product?

  1. Lactobacillus, Propionibacterium, Saccharomyces

  2. Bacillus, Clostridium, Saccharomyces

  3. Clostridium, Lactobacillus, Propionibacterium

  4. Bacillus, Clostridium, Lactobacillus

  5. Bacillus, Lactobacillus, Streptococcus


Correct Option: E
Explanation:

Bacillus, Lactobacillus, Streptococcus: All the three yield lactic acid as fermentation end product.

Which of the following sulfate-reducing bacteria uses CO2 from reverse TCA cycle as major C-Source?

  1. Archaeoglobus

  2. Desulfobacter

  3. Desulfobacterium

  4. Desulfotomaculum

  5. Thermodesulfobacterium


Correct Option: B
Explanation:

Desulfobacter uses CO2 from reverse TCA cycle as major C-Source.

Ethanol is one of the fermentation end products of

  1. Enterobacter
  2. Escherichia
  3. Clostridium
  4. Saccharomyces
  5. Salmonella
  6. Streptococcus
  1. 1, 2 and 3 only

  2. 1, 2, 4 and 5 only

  3. 2, 3 and 4 only

  4. 2, 4, 5 and 6 only

  5. all of the above


Correct Option: B
Explanation:

Enterobacter yields ethanol, lactic acid, formic acid, butanediol, acetoin, CO2, and H2 as fermentation end product. Escherichia yields ethanol, lactic acid, succinic acid, acetic acid, CO2, and H2 as fermentation end product. Saccharomyces yields ethanol and CO2 as fermentation end products. Salmonella yields ethanol, lactic acid, succinic acid, acetic acid, CO2, and H2 as fermentation end product.

Match the column – I (Microorganism) with column – II (Industrial product) and select the correct option.

 
Column – I Column – II
P. Gluconobacter 1. Cheese
Q. Aspergillus 2. Citric Acid
R. Streptococcus 3. Vitamin C
S. Saccharomyces 4. Glycerol
  1. P - 1, Q - 2, R - 3, S - 4

  2. P - 2, Q - 1, R - 4, S - 3

  3. P - 3, Q - 2, R - 1, S - 4

  4. P - 4, Q - 2, R - 3, S - 1

  5. P - 4, Q - 3, R - 2, S - 1


Correct Option: C
Explanation:

Gluconobacter species are used for oxidation of D-sorbitol into L-sorbose in the commercial production of vitamin C (ascorbic acid). Various strains of Aspergillus niger are used in the industrial preparation of citric acid. Streptococcus thermophilus is used in making reduced-fat cheese with similar characteristics to regular full-fat cheese. Glycerol is a major by-product of ethanol fermentation by Saccharomyces cerevisiae.

Match the column – I (Energy-Producing Process) with column – II (Final Electron Acceptor) and select the correct option.

 
Column – I Column – II
A. Aerobic Respiration 1. An organic molecule
B. Anaerobic Respiration 2. Molecular oxygen
C. Fermentation 3. An inorganic substances
  1. A - 1, B - 2, C - 3

  2. A - 1, B - 3, C - 2

  3. A - 3, B - 1, C - 2

  4. A - 3, B - 2, C - 1

  5. A - 2, B - 3, C - 1


Correct Option: E
Explanation:

Final electron acceptor in aerobic respiration is molecular oxygen. The final electron acceptors in anaerobic respiration include NO3, SO42–, and CO32–. The final electron acceptor in fermentation is an organic molecule.

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