Microbes as Biofertilisers - Rhizobium, Azospirillum, Mycorrhiza - Unsolved Practice Set
Chapter: Microbes in Human Welfare | Topic: Microbes as Biofertilisers Rhizobium Azospirillum Mycorrhiza
MICROBES AS BIOFERTILISERS - RHIZOBIUM, AZOSPIRILLUM, MYCORRHIZA - UNSOLVED PRACTICE SET
Topic: Microbes as Biofertilisers Rhizobium Azospirillum Mycorrhiza
Multiple Choice Questions
Q1. Biofertilisers are organisms that:
- Kill harmful pests in soil
- Enrich the nutrient quality of soil, often through nitrogen fixation or nutrient absorption
- Replace the need for water in agriculture
- Are always harmful to crop plants
Q2. Rhizobium bacteria are well known for their symbiotic relationship with:
- Cereal crops like wheat and rice
- Leguminous plants, where they form root nodules and fix atmospheric nitrogen
- Fungal spores only
- Aquatic plants only
Q3. Azospirillum and Azotobacter are examples of:
- Symbiotic nitrogen-fixing bacteria found only in legume roots
- Free-living nitrogen-fixing bacteria found in the soil
- Fungi used only for biocontrol
- Viruses used in biofertilisers
Q4. Mycorrhiza refers to a symbiotic association between fungi and:
- Animal cells
- Plant roots
- Bacterial colonies
- Viral particles
Q5. One key benefit that mycorrhizal fungi provide to their host plant is:
- Reduced water absorption
- Improved absorption of phosphorus and water, along with resistance to certain root-borne pathogens
- Complete resistance to all types of stress
- No measurable benefit at all
Short Answer Questions
Q6. Define biofertilisers, and explain why they are considered a more sustainable alternative to chemical fertilisers.
Q7. Describe the symbiotic relationship between Rhizobium and leguminous plants.
Q8. Differentiate between Rhizobium and Azospirillum/Azotobacter in terms of how they fix nitrogen.
Q9. What is mycorrhiza, and what benefits does it provide to the host plant?
Long Answer Questions
Q10. Discuss the role of Rhizobium as a biofertiliser, explaining the process of symbiotic nitrogen fixation in legume root nodules.
Q11. Explain the significance of free-living nitrogen-fixing bacteria (like Azospirillum) and mycorrhizal fungi in improving soil fertility and plant health.
APPLICATION / ANALYSIS
Q12. A farmer growing a leguminous crop like chickpea notices that the soil in that field remains fertile for the next crop, even without adding much nitrogen-based fertiliser. Explain, using your understanding of Rhizobium and biological nitrogen fixation, why this might be happening.
Q13. An agricultural scientist recommends inoculating a farmer's crop roots with a mycorrhizal fungus before planting, especially in a field with historically low phosphorus availability. Explain how this recommendation could help address the farmer's specific soil fertility problem.