Fermentation Technology Questions and Answers – Practical Benefits – Citric Acid Production

This set of Fermentation Technology Multiple Choice Questions & Answers (MCQs) focuses on “Practical Benefits – Citric Acid Production”.

1. Who first isolated citric acid?
a) Thomas Edison
b) Carl Wilhelm
c) Charles Darwin
d) Francis Crick
View Answer

Answer: b
Explanation: Carl Wilhelm Scheele in 1784 first isolated citric acid from lemon juice. He crystallized citric acid from lemon juice and this method became the primary method for the production of citric acid.

2. Citric acid is a ____________ acid.
a) Monobasic
b) Tribasic
c) Monoprotic
d) Tribasic
View Answer

Answer: d
Explanation: Citric acid (2-Hydroxy-1,2,3-propane tricarboxylic acid) is a tribasic acid which can yield three hydrogen ions (free) upon ionization of each molecule of acid. It is also called as triprotic acid. Phosphoric acid is another example of tribasic or troprotic acid.

3. Who observed citric acid as a by-product of calcium oxalate produced by Penicillium glaucum?
a) Thomas Edison
b) Carl Wilhelm
c) Wehmer
d) Adam
View Answer

Answer: c
Explanation: Wehmer in 1893 observed citric acid as a by-product of calcium oxalate produced by Penicillium glaucum. This resulted in the encouragement of the production of citric acid.
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4. Which of the following is used in the manufacturing of cheese?
a) Sulphuric acid
b) Amylase
c) Kinase
d) Sodium citrate
View Answer

Answer: d
Explanation: Sodium citrate has been used in the manufacturing of cheese. It is also used in the transfusion of blood and bacteriology for the prevention of bacteriology. It can also serve as a source of energy.

5. Which of the following is the most common method for citric acid production?
a) Solid-state fermentation
b) Submerged fermentation
c) Surface fermentation
d) Surface adhesion fermentation
View Answer

Answer: b
Explanation: Submerged fermentation is the most common method for the production of citric acid. It is the most commonly employed technique and it is estimated that about 80 % of the world production of citric acid is obtained by submerged fermentation.
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6. Which of the following organisms is not used for the production of citric acid?
a) Aspergillus wentii
b) Bacillus licheniformis
c) Candida oleophila
d) Saccharomyces cerevisiae
View Answer

Answer: d
Explanation: Saccharomyces cerevisiae is not used for the production of citric acid. It is mainly used in the production of beer as it is a brewers’ yeast. Aspergillus niger, Aspergillus wentii, Bacillus licheniformis, Candida oleophila, etc. are used in the production of citric acid.

7. The first product of TCA cycle is ___________
a) Fumaric acid
b) Oxalic acid
c) Malic acid
d) Citric acid
View Answer

Answer: d
Explanation: The first product of TriCarboxylic Acid cycle is citric acid. Therefore, it is also called a citric acid cycle or Krebs cycle. The cycle is primarily regulated by the concentration of ATP, NADH and is controlled by the key enzymes like isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, etc.
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8. Which of the following fruit contain more amount of citric acid?
a) Mango
b) Tomato
c) Orange
d) Coconut
View Answer

Answer: c
Explanation: Oranges contain more amount of citric acid including lemon, lime, grapefruit, etc. are high in citrus whereas tomatoes contain a low amount of citric acid and coconut and mango do not contain citric acid at all.

9. Citrate is the feedback inhibitor of ____________
a) Hexokinase
b) Phosphofructokinase
c) Pyruvate dehydrogenase
d) Malate dehydrogenase
View Answer

Answer: b
Explanation: Citrate is the feedback inhibitor of phosphofructokinase (PFK). The reduction or inhibition of Phosphofructokinase is required for the good accumulation of citric acid.
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10. Magnesium hydroxide is used to precipitate calcium citrate.
a) True
b) False
View Answer

Answer: b
Explanation: Magnesium hydroxide cannot be used for the precipitation of calcium citrate as some of the acids may get lost in the solution as magnesium citrate if magnesium is added. The addition of magnesium-free calcium hydroxide is used for the precipitation of calcium citrate.

11. Citric acid is used in the manufacture of jams and jellies.
a) True
b) False
View Answer

Answer: a
Explanation: Citric acid is used in the manufacture of jams and jellies. It is also used in the manufacture of sweets and soft drinks. It can also be used for artificial flavoring of various foods and is also used in the manufacture of processed cheese.

12. Who discovered the citric acid cycle?
a) Hans Krebs
b) Carl Wilhelm
c) Wehmer
d) Adam
View Answer

Answer: a
Explanation: Citric acid cycle was discovered by Sir Hans Adolf Krebs and these studies were performed in the breast muscle of pigeon as the breast muscle was a powerful muscle for flight and the oxidative capacity of the breast muscle was maintained even after its disruption and suspension in aqueous media. It is also called a Krebs’ cycle.

13. Citric acid cycle occurs in _____________
a) Vacuoles
b) Golgi apparatus
c) Mitochondria
d) Nucleus
View Answer

Answer: c
Explanation: The citric acid cycle or TriCarboxylic acid cycle occurs in the innermost compartment of mitochondria where the chemical energy is generated from the end product of the glycolysis pathway. It occurs in mitochondria of eukaryotes whereas, in prokaryotes, it occurs in the cytoplasm.

Sanfoundry Global Education & Learning Series – Fermentation Technology.

To practice all areas of Fermentation Technology, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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