Answer: Biofertilizers use living microorganisms to enrich soil nutrients naturally.
- A Biofertilizers contain synthetic nitrogen compounds manufactured industrially
- B Biofertilizers use living microorganisms to enrich soil nutrients naturally
- C Biofertilizers act considerably faster than conventional chemical fertilizers
- D Biofertilizers are effective exclusively within tropical soil conditions
Correct answer: B. Biofertilizers use living microorganisms to enrich soil nutrients naturally
Explanation: Biofertilizers contain living microorganisms (bacteria, fungi, cyanobacteria) that naturally fix nitrogen or solubilize nutrients, unlike chemical fertilizers which are synthetic inorganic compounds.
Sewage passes through physical removal (primary), then aerobic biological treatment where microbes form flocs that consume organic matter (secondary); the settled activated sludge is then digested anaerobically to produce biogas - a deliberate switch from aerobic to anaerobic conditions between stages.
Concept context
Microorganisms in food, medicine, sewage treatment, biocontrol, and biofertilizers