Consider statements about microorganisms: 1. Cyanobacteria are photosynthetic prokaryotes. 2. Mycorrhiza is a symbiotic association between fungi and plant roots. 3. Nitrosomonas is a denitrifying bacterium. Which are correct? MCQ with Answer and Explanation

Cyanobacteria (blue-green algae) are photosynthetic, oxygenic prokaryotes that play a crucial role in nitrogen fixation in aquatic and terrestrial ecosystems. Mycorrhiza is a mutualistic symbiotic association between a fungus and the roots of a vascular plant, where the fungus aids in nutrient absorption and the plant provides carbohydrates. Nitrosomonas is a nitrifying bacterium that converts ammonia to nitrite; denitrifying bacteria like Pseudomonas convert nitrates to nitrogen gas. Thus, statements 1 and 2 are correct.