Consider the following statements regarding 'bioremediation'. It involves the use of bacteria and fungi to

Answer: (c) 1, 2 and 3 are correct

Aquifers, toxic dumps and oil spills are all cleaned with microbes. Curing disease is not remediation.

Statement by statement

1. ✓ YES Microbes degrade contaminants in groundwater, often helped by pumping in oxygen and nutrients.

2. ✓ YES Toxic waste sites are cleaned by microbes that break down organic pollutants, and by plants (phytoremediation).

3. ✓ YES Oil-eating bacteria (Ananda Chakrabarty’s engineered Pseudomonas, the “superbug”) break down hydrocarbons.

4. ✗ NO Curing disease is medicine (antibiotics), not cleaning the environment.

The idea

Bioremediation is cleaning the environment with living things, mostly microbes that feed on the pollutant. It can be done on the spot (in-situ) or after removing the soil or water for treatment (ex-situ).

Polluted groundwater: pump in air and nutrients → native microbes multiply → Toxic dump: spread and turn the soil → microbes break down the waste → Oil spill: spray nutrients or oil-eating bacteria on the slick

Why the others are wrong

(a) Leaves out oil spills — the best-known example.

(b) Leaves out toxic dumps, though they are a textbook target.

(d) Treats curing disease as remediation. Antibiotics come from microbes, but that is medicine.

The trap

Antibiotics come from fungi and bacteria, so statement 4 feels related. Bioremediation cleans the ENVIRONMENT.

Also know

After the Exxon Valdez oil spill in Alaska (1989), fertiliser was sprayed on beaches to feed oil-eating bacteria. Fungi can be used too (mycoremediation), and plants (phytoremediation).