UPSC Prelims 2013·GS1·science-and-technology·ipr and biotechnology

Consider the following organisms : 1. Agaricus 2. Nostoc 3. Spirogyra Which of the above is/are used as biofertilizer/biofertilizers?

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Last updated 23 May 2026, 3:31 pm IST
  1. A(a) 1 and 2
  2. B(b) 2 onlyCorrect
  3. C(c) 2 and 3
  4. D(d) 3 only

Explanation

The correct answer is B) 2 only (Nostoc). Nostoc is a cyanobacterium (blue-green algae) capable of nitrogen fixation. This means it converts atmospheric nitrogen into ammonia, a form usable by plants. Therefore, it's widely used as a biofertilizer, particularly in rice paddies. Agaricus is a genus of mushrooms. While beneficial as a food source and in decomposition, it doesn't fix nitrogen and isn't used as a biofertilizer. Spirogyra is a filamentous green algae. It contributes to oxygen production through photosynthesis but doesn't fix nitrogen and isn't a biofertilizer. Therefore: Option A (1 and 2) is incorrect because Agaricus is not a biofertilizer. Option C (2 and 3) is incorrect because Spirogyra is not a biofertilizer. Option D (3 only) is incorrect because Spirogyra is not a biofertilizer.
science-and-technology: Consider the following organisms : 1. Agaricus 2. Nostoc 3. Spirogyra Which of the above is/are used as biofertilizer/bi
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