UPSC Prelims 2013 · Question 47 of 99
UPSC Prelims 2013 question on Mycorrhizal Biotechnology
- ExamUPSC CSE
- Year2013
- PaperGeneral Studies Paper I
- SubjectScience and Technology
- TopicBiotechnology
- DifficultyHard
- TypeStatement
Mycorrhizal biotechnology has been used in rehabilitating degraded sites because mycorrhiza enables the plants to:
1. Resist drought and increase absorptive area
2. Tolerate extremes of pH
3. Resist disease infestation
Select the correct answer using the codes given below:
Show answer
Answer: D. 1, 2 and 3
Verdict
Correct Answer: 1, 2 and 3
Analysis
According to the official UPSC Answer Key for Prelims 2013 General Studies Paper, the correct option is 1, 2 and 3.
Mycorrhiza is a symbiotic association between fungi and plant roots. It helps plants survive in degraded sites by improving water absorption, nutrient uptake, stress tolerance and disease resistance.
Statement by statement
1. Resist drought and increase absorptive area — Correct
Mycorrhizal fungi have thin thread-like structures called hyphae.
These hyphae spread beyond the plant root zone and increase the absorptive surface area.
This helps plants absorb more water and nutrients, especially phosphorus, and survive better in dry and degraded soils.
2. Tolerate extremes of pH — Correct
Mycorrhizal fungi help modify the soil environment around plant roots.
They can secrete organic acids and improve nutrient availability in acidic or alkaline soils.
Thus, they help plants tolerate pH stress in degraded sites.
3. Resist disease infestation — Correct
Mycorrhiza provides biological protection to plant roots.
It competes with pathogens for space and nutrients and can also stimulate the plant’s defence response.
Therefore, it helps plants resist disease infestation.
Extra UPSC info
* Mycorrhiza is a mutualistic relationship: the plant gives sugars to the fungus, while the fungus supplies water and minerals to the plant.
* Mycorrhiza is especially important for phosphorus uptake, as phosphorus is often fixed in soil and not easily available to roots.
* Mycorrhizal biotechnology is useful in ecological restoration, afforestation and rehabilitation of degraded lands.
* It can help plants survive in mining and industrially degraded sites by reducing heavy metal stress.
* Mycorrhizal fungi are used as biofertilizers in sustainable agriculture.
* Ectomycorrhiza forms a sheath around roots, while endomycorrhiza or arbuscular mycorrhiza penetrates root cells.
How to crack it
Mycorrhiza helps plants absorb more water and nutrients, tolerate pH stress and resist diseases, so all three statements are correct.
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