Environmental Biotechnology Multiple Choice Questions on “Metal – Microbe Interactions”.
1. Which of the following is not a sub division of Metal – Microbe Interactions?
a) Intra cellular accumulation
b) Transformation of metals
c) Cell wall-metal interaction
d) Hydrolysis
Answer: d
Clarification: Hydrolysis is not a sub division of Metal – Microbe interactions that happens between microorganisms and metal, it is a method which refers to the breakdown of chemical substances by means of water, whereas, metal – Microbe Interactions can be sub divided into intra cellular accumulation, transformation of metals, cell wall-metal interaction, polymer metal interactions and volatilization of metals.
2. Which of the following functions is not important to assimilation of metals by bacteria?
a) Detoxification
b) Enzyme functions
c) Physical properties of cell
d) Resistance
Answer: d
Clarification: Resistant population is selected over the original strain, that affects the microbial population, may also lead to reduction in abundance and diversity of species but this is not relevant to assimilation of metals by bacteria, whereas, detoxification, enzyme functions, physical properties of cell are important during bacterial assimilation of metals in the cells.
3. 0.3 % of trace metals can be found in E. coli.
a) True
b) False
Answer: a
Clarification: E. coli or Escherichia coli can accumulate metals inside it’s cell by bacterial assimilation. The bacteria can assimilate the metals in its protoplasm by first binding of the ligand to the metal and secondly by slow transport inside the cell. About 0.3 % of trace metals can be found in E. coli.
4. Which of the following binds to toxic metals?
a) Extracellular ligands
b) Intercellular ligands
c) Intracellular ligands
d) Integral proteins
Answer: a
Clarification: The extracellular ligands or the cell wall ligands bind to the toxic metals and that helps in bacterial assimilation of metals. Integral proteins, Intercellular ligands or Intracellular ligands do not bind to the toxic metals in the environment nearby, only the Extracellular ligands bind.
5. Which of the following trace elements are not found in Escherichia coli?
a) Copper
b) Zinc
c) Manganese
d) Phytoremediation
Answer: d
Clarification: Phytoremediation is a technique used to remove heavy metals in the environment using plants, so, that would lead to their reduction in the environment. Whereas, Copper, Zinc, manganese and molybdenum are the trace elements are found in Escherichia coli. E. coli can accumulate metals inside it’s cell by bacterial assimilation, these are among the 0.3 % of trace metals can be found in E. coli.
6. Which of the following is not considered toxic metals?
a) Zinc
b) Copper
c) Uranium
d) H2O
Answer: d
Clarification: Water or H2O is considered as nontoxic, without any contamination water does not cause any harm to the environment and is not toxic at all, whereas, uranium on the other hand is radioactive and highly toxic, also, copper and zinc, both of them are considered to be toxic metals.
7. Which of the following can stimulate chemolithotrophic growth in bacteria?
a) Uranium
b) Nickle
c) Copper
d) Cadmium
Answer: b
Clarification: Nickle is used in many organisms for their growth purposes as they are used as a component of hydrogenase in various microorganisms, Nickle can stimulate chemolithotrophic growth in bacteria. But Uranium is radioactive and highly toxic, copper and cadmium are toxic and they do not stimulate chemolithotrophic growth in bacteria.
8. A large number of bacteria can accumulate which metal?
a) Cadmium
b) Water
c) Carbon dioxide
d) Fungus
Answer: a
Clarification: Cadmium metal is found to be accumulated by a lot of bacterial species. Transport of cadmium inside the cell is dependent on the transport of the cell. Whereas, water and carbon dioxide are not metals. Also, Fungus itself is a microorganism and not a metal, so, cadmium is the right option.
9. What happens after death of the bacteria that has metal accumulation?
a) Metal species released
b) Metal species degraded
c) Free metal species released
d) Free metal species dissolves
Answer: a
Clarification: Metal species released after death of the bacteria that has metal accumulation is compared less toxic than the actual free metal species released in the environment. If the metal is not assimilated by the bacteria and released in the environment, it shows higher toxic potential. After the death of the bacteria, the microorganisms produce aggregates that form complexes with the metals and hence, released into the surrounding after the death of the bacteria.
10. Using microorganisms to extract metals from ores and mine waste is called as?
a) Biomining
b) Bioleaching
c) Afforestation
d) Hydrolysis
Answer: a
Clarification: Hydrolysis is a method which refers to the breakdown of chemical substances by means of water, whereas, afforestation is planting of trees in the forest to restore the flora and fauna and help control pollution the environment, Biomining is the extraction of metals from their ores or mine waste using of microbes, whereas, bioleaching is dissolution of metals from ores using various microorganisms.
11. Intracellular machinery degrades metals.
a) True
b) False
Answer: a
Clarification: The intracellular machinery of the bacteria that accumulates metals has the potential to degrade the metals to a much less toxic form, as, they use enzymes to convert the toxic metal into less toxic form in the intracellular region, which further does not result in accumulation.
12. Which of the following cannot methylate mercury?
a) E. coli
b) Bacillus
c) Clostridium
d) Oxygen
Answer: d
Clarification: Bacteria like E. coli, Bacillus, Clostridium and Pseudomonas can methylate mercury in an area which is more enriched with sulphate. The habitats which have less sulphates or reduced form of sulphates, the methylation of mercury is not possible. However, oxygen doesn’t combine with mercury under normal temperature and hence, it cannot take part in the methylation of the mercury.