This set of Environmental Biotechnology Multiple Choice Questions & Answers (MCQs) focuses on “Microbial Transformations of Pesticides – Oxidative Dealkylation”.
1. Which of the following groups can be de-alkylated by microorganisms?
a) N-linked alkylated groups
b) C-linked alkylated groups
c) F-linked alkylated groups
d) G-linked alkylated groups
View Answer
Explanation: N-linked alkylated groups and O-linked alkylated groups can be easily de-alkylated by microorganisms, also something that is bonded to the carbon frame are often more resistant to the breakdown. Also, alkyl groups of all the known pesticides are usually attached to the nitrogen atom and oxygen atom. So, C-linked alkylated groups cannot be de-alkylated by microorganisms. F-linked alkylated groups and G-linked alkylated groups doesn’t take part in the process.
2. Why is S-dealkylation not observed?
a) Greater inclination for oxidation of Sulphur
b) Lesser inclination for oxidation of Sulphur
c) Lesser inclination for reduction of Sulphur
d) Greater inclination for reduction of Sulphur
View Answer
Explanation: S-dealkylation is usually not observed due to greater inclination for oxidation of Sulphur. Sulphur has higher chances to oxidation to form sulphone or sulphoxide. These are nonspecific oxidation reactions; hence, it requires various hydrogen donors. Hence, lesser inclination for oxidation of Sulphur, lesser inclination for reduction of Sulphur, greater inclination for reduction of Sulphur is usually not the case for S-dealkylation.
3. Dealkylation is caused as a co-metabolism process in fungi.
a) True
b) False
View Answer
Explanation: Dealkylation can happens in different fungal species, mostly is caused as a co-metabolism process in fungi. Aspergillus sp. are usually involved in dealkylation process. In fungi, the dealkylation is usually caused by different fungi as a co-metabolism process.
4. How does microbial arbitrated removal of alkyl group from nitrogen atom takes place?
a) Hydroxy-methyl intermediates
b) Intercellular ligands
c) Extracellular ligands
d) Integral proteins
View Answer
Explanation: The reaction is often catalyzed by various oxidases; hydroxy-methyl intermediates are usually used for removal of alkyl group from nitrogen atom that is often arbitrated by microorganisms. Extracellular ligands, Integral proteins or Intercellular ligands doesn’t help in removal of alkyl group from nitrogen atom.
5. Which of the following microorganisms is involved in dealkylation process?
a) Birds
b) Fungi
c) Human
d) Vertebrates
View Answer
Explanation: Fungi is also involved in dealkylation process, as it has enzymes which helps in the dealkylation process. Whereas, birds, human, vertebrates are complex organisms and hence, they are not involved in dealkylation process. Aspergillus sp. are usually involved in dealkylation process.
6. How fungi help in de-alkylation?
a) Oxidation
b) Reduction
c) Assimilation
d) Accumulation
View Answer
Explanation: Usually, oxidation of the groups helps in de-alkylation process, fungi help in de-alkylation process. Reduction of atom does not usually help in de-alkylation. Assimilation and accumulation do not help in de-alkylation process.
7. Which of the following is not a method of dealkylation using microorganisms?
a) Adsorption
b) Chemical precipitation
c) Microbial demethylations
d) Reverse osmosis
View Answer
Explanation: Microbial demethylations is a process which is used for de-alkylation using microorganisms like fungi and bacteria using the process of oxidation. Whereas, adsorption, chemical precipitation, reverse osmosis and solvent extraction is used for heavy metal removal from water and it does not help in method of dealkylation using microorganisms.
8. Which of the following technique is used to metabolize cresols?
a) Activated Alumina
b) Microbial dealkylation
c) Reverse osmosis
d) Chemical precipitation
View Answer
Explanation: Microbial dealkylation, also known as Microbial demethylations helps to metabolize cresols to methyl catechols without loss of any substituent of alkyl group. Chemical precipitation is used to remove heavy metals by use of chemicals which ultimately leads to precipitation of the heavy metals but it doesn’t filter out. Activated Alumina and Reverse osmosis is used to filter out heavy metals.
9. Pesticides with more than one alkoxyl group cannot be de-alkylated.
a) True
b) False
View Answer
Explanation: Pesticides usually have side chains which has one or more alkyl groups. In case, the pesticide does not have more than one alkoxyl group, it cannot be de-alkylated. So, it has to have more than one alkyl group to be de-alkylated.
10. Which of the following can have more than one alkoxyl groups?
a) Pesticides
b) Distilled water
c) Coffee
d) Acetone
View Answer
Explanation: Pesticides can have more than one alkoxyl group which helps in de-alkylation process. The easy of dealkylation of Distilled water, Coffee, Acetone does not depend on the alkoxyl groups present in them or how many of the groups present.
11. Herbicides can undergo microbial dealkylation.
a) True
b) False
View Answer
Explanation: Herbicides can undergo microbial dealkylation in the O-linked side chains and hence, these categories of pesticides can undergo the process of dealkylation using various microorganisms in the soil. The alkyl groups attached the pesticides are usually removed by the process of O-dealkylation.
12. Which of the following bacteria metabolizes cresols?
a) Pesticides
b) Pseudomonads
c) Fungi
d) Algae
View Answer
Explanation: Pseudomonads is a type of bacteria that helps to metabolise cresols into methyl catechols and hence, helps in de-alkylation of pesticides. Pesticides cannot metabolise pesticides themselves, whereas, Fungi and algae are usually not categorized as bacteria that would help in metabolisation of cresols.
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