NEET-UG Biology · Class 12
Microbes as biocontrol agents and biofertilisers — NEET & JEE Questions
Microbes as biocontrol agents and biofertilisers is a topic in Microbes in Human Welfare, a Class 12 Biology chapter of the NEET-UG syllabus. TestBudy holds 13 published NEET-UG questions on Microbes as biocontrol agents and biofertilisers, each with the marking scheme of the real paper.
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Microbes as biocontrol agents and biofertilisers MCQs with solutions
10 of the 13 published questions on this topic, exactly as they appear in a test. Answers and worked solutions come with your result rather than on this page.
Which bacterium is used as a microbial biocontrol agent against insect pests?
- A. Lactobacillus
- B. Rhizobium leguminosarum
- C. Bacillus thuringiensis
- D. Methanobacterium
Which symbiotic bacterium fixes nitrogen in root nodules of many leguminous plants?
- A. Streptococcus
- B. Saccharomyces
- C. Penicillium
- D. Rhizobium
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
Dried spores of a bacterium are mixed with water and sprayed onto vulnerable plants; when caterpillars eat the leaves, the toxin is released in their gut and the larvae die. The bacterium is
- A. Trichoderma
- B. Bacillus thuringiensis
- C. Rhizobium
- D. Azotobacter
Free-living fungi that are very common in root ecosystems and are effective biocontrol agents against several plant pathogens belong to the genus
- A. Glomus
- B. Anabaena
- C. Trichoderma
- D. Penicillium
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
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
A farmer wants to control a caterpillar pest without harming pollinating bees, birds or fish, as part of an integrated pest management programme. Which agent best meets these requirements, and why?
- A. A broad-spectrum chemical insecticide, because it kills quickly
- B. Rhizobium, because it fixes nitrogen
- C. Trichoderma, because it kills all insects
- D. A baculovirus of the genus Nucleopolyhedrovirus, because it is species-specific and narrow-spectrum, with no negative impact on plants, mammals, birds, fish or non-target insects
A farmer growing a non-leguminous crop wants to enrich soil nitrogen using microbes that do not need a root nodule. Which biofertiliser is suitable?
- A. Free-living bacteria such as Azospirillum and Azotobacter
- B. Rhizobium
- C. Glomus
- D. Bacillus thuringiensis
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
Common mistakes in Microbes as biocontrol agents and biofertilisers
Recorded against questions in this topic that are not shown above, so none of these points at an answer you can see on this page.
- Assuming a good biocontrol agent must kill the widest possible range of organisms.
- Attributes nitrogen fixation to a mycorrhizal fungus.
- Gives cyanobacteria a nodule-forming or phosphorus-supplying role.
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