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Microbes as biocontrol agents and biofertilisers — practice questions

7 questions in the bank on this idea. Below are 7 of them, exactly as they appear in a test.

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  1. Question 1 · difficulty L1 · recall

    Which bacterium is used as a microbial biocontrol agent against insect pests?

    • A. Lactobacillus
    • B. Rhizobium leguminosarum
    • C. Bacillus thuringiensis
    • D. Methanobacterium

  2. Question 2 · difficulty L1 · recall

    Which symbiotic bacterium fixes nitrogen in root nodules of many leguminous plants?

    • A. Streptococcus
    • B. Saccharomyces
    • C. Penicillium
    • D. Rhizobium

  3. Question 3 · difficulty L2 · understanding

    How do mycorrhizal fungi benefit many crop plants?

    • A. They replace all root tissues
    • B. They improve phosphorus uptake
    • C. They prevent photosynthesis
    • D. They convert leaf tissues into permanent nitrogen-fixing nodules

  4. Question 4 · difficulty L3 · application

    What is a major advantage of using microbial biocontrol agents?

    • A. They reduce dependence on chemical pesticides
    • B. They eliminate every organism, including beneficial species, from the field
    • C. They always act faster than chemicals
    • D. They make crop monitoring unnecessary

  5. Question 5 · difficulty L3 · application

    A farmer inoculates rice fields with cyanobacteria such as Anabaena and Nostoc. What is the main expected benefit?

    • A. Direct synthesis of pesticides inside rice grains
    • B. Methane production for the crop
    • C. Biological nitrogen fixation
    • D. Removal of all soil microbes

  6. Question 6 · difficulty L4 · analysis

    A crop root system is colonised by Glomus. Which change would best indicate a successful association?

    • A. Suppression of every soil bacterium around the entire root system
    • B. Loss of all root hairs
    • C. Complete absence of soil fungi
    • D. Improved phosphorus uptake

  7. Question 7 · difficulty L5 · analysis

    A pest-management programme uses a baculovirus that infects a narrow range of insect hosts. Why can this be ecologically useful?

    • A. It spares many non-target organisms
    • B. It kills all insects equally
    • C. It acts by increasing soil nitrogen
    • D. It completely replaces both fertilisation and all other pest-management methods

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