- A. 1 only
- B. 2 and 3 only
- C. 1 and 3 only
- D. 1, 2 and 3
Answer: C
Explanation
Statement 1 is correct. Bioremediation is treatment that uses naturally occurring organisms to break down hazardous substances into less toxic or non-toxic substances. It uses microorganisms to degrade organic contaminants in soil, groundwater, sludge, and solids. The microorganisms break down contaminants by using them as an energy source or cometabolizing them with an energy source. Statement 2 is not correct. Not all contaminants are easily treated by bioremediation using microorganisms. For example, heavy metals such as cadmium and lead are not readily absorbed or captured by microorganisms. Statement 3 is correct. Genetic engineering has been used to create organisms designed for specific purposes. For e.g. bacterium Deinococcus radiodurans (the most radioresistant organism known) has been modified to consume and digest toluene and ionic mercury from highly radioactive nuclear waste.