Question

Which of the following is a pair of biofertilizer?

• A. Azolla and BGA
• B. Nostoc and legume
• C. Rhizobium and grasses
• D. Salmonella and E. coli

Hint:

Important biofertilizers from NCERT: \[ \textit{Rhizobium} \] \[ \textit{Azotobacter} \] \[ \textit{Anabaena} \] \[ \textit{Nostoc} \] \[ \textit{Azolla-Anabaena} \] For paddy fields, remember: \[ \boxed{\text{Azolla + BGA}} \] as a highly important biofertilizer combination.

Answer 1

The Correct Option is A

Step 1: Recall the meaning of biofertilizers. Biofertilizers are living microorganisms that enrich soil fertility by increasing the availability of nutrients, especially nitrogen and phosphorus.

Step 2: Examine the given options.
• Azolla is a water fern associated with the nitrogen-fixing cyanobacterium Anabaena. It is widely used as a biofertilizer in paddy fields. \(\checkmark\)
• BGA (Blue-Green Algae) such as Nostoc and Anabaena are important nitrogen-fixing biofertilizers. \(\checkmark\)
• Legume is a plant, not a biofertilizer. \(\times\)
• Grasses are not biofertilizers. \(\times\)
• Salmonella and E. coli are bacteria, but they are not used as biofertilizers. \(\times\)

Step 3: Identify the correct pair. Among the given options, only \[ \boxed{\text{Azolla and BGA}} \] are both used as biofertilizers. Therefore, \[ \boxed{\text{(A) Azolla and BGA}} \] is the correct answer.