Consider the following organisms:1. Agaricus2. Nostoc3. SpirogyraWhich of the above is/are used as biofertilizer/biofertilizers?
✓ Correct answer: b) 2 only
ExplanationBio-fertilizers are living or biologically active products or microbial inoculants of bacteria, algae and fungi (separate- ly or in combination) which are able to enrich the soil with ni- trogen, phosphorus, organic matter etc.Statement 1 is incorrect: Agaricus refers to a genus of fun- gi, commonly known for species like Agaricus bisporus, the common button mushroom.While it is used in culinary and medicinal contexts, it is not used as a biofertilizer.They are not involved in nitrogen fixation or other activities that promote soil fertility, which are characteristic of biofertilizers.Statement 2 is correct: Nostoc is a genus of cyanobacte- ria (blue-green algae) that can fix atmospheric nitrogen.It is often used as a biofertilizer because of its ability to enhance soil fertility by converting atmospheric nitrogen into a form that plants can utilize.Nostoc is commonly found in rice paddies and is used to improve nitrogen content in the soil, especially in or- ganic farming.Statement 3 is incorrect: Spirogyra is a genus of green algae that primarily plays a role in freshwater e
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