Which one of the following is NOT a biocontrol agent ?
- A.Bacillus thuringiensis
- B.Ladybird beetle
- C.Trichoderma
- D.Aphid
Correct answer
Explanation
The correct answer is D, Aphid. An aphid is a sap-sucking insect pest of crops, so it is the target of biocontrol, not an agent of it.
Biological control means using living organisms, or their products, to keep pests and plant diseases in check instead of chemical pesticides. Aphids are small, soft-bodied insects that suck sap from tender shoots of mustard, cotton, vegetables and many other crops, and they also spread plant viruses. They are themselves controlled by predators such as ladybird beetles and the larvae of lacewings. Biocontrol is a key part of organic farming and integrated pest management.
Option A is wrong because Bacillus thuringiensis is a soil bacterium whose Cry toxin kills caterpillars; it is sprayed as a biopesticide and its gene is used in Bt cotton. Option B is wrong because the ladybird beetle is a well-known predator that eats aphids. Option C is wrong because Trichoderma is a free-living fungus that controls many soil-borne fungal diseases of plants.
Exam tip: ladybird eats aphids, dragonfly eats mosquitoes, Bt kills caterpillars, Trichoderma fights plant fungi, Baculovirus attacks insects.
Practice Questions
View allThe city of Cartagena, which is famous for Protocol on Biosafety, is located in
- A.Colombia
- B.Venezuela
- C.Brazil
- D.Guyana
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Cartagena is a port city on Colombia's Caribbean coast, where talks on the biosafety protocol were held in 1999. The Cartagena Protocol on Biosafety is a supplementary agreement to the Convention on Biological Diversity of 1992.
Read the full explanation →Which of the following can be considered associated with mitigation of environmental problems ?
- A.Biomagnification
- B.Accelerated eutrophication
- C.Release of Nuclear wastes
- D.Categorical disposal of different wastes
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Sorting wastes into categories and disposing of each in the proper way reduces pollution, so it helps solve environmental problems rather than cause them.
Read the full explanation →Which one of the following is the nodal agency in India for the United Nations Environment Programme?
- A.The Ministry of Environment, Forest and Climate Change
- B.The Ministry of Science and Technology
- C.The Ministry of Earth Sciences
- D.The Ministry of Home Affairs
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This ministry plans, promotes and coordinates India's environmental policy, so it deals with UNEP on India's behalf. UNEP was set up in 1972 after the United Nations Conference on the Human Environment in Stockholm and has its headquarters in Nairobi, Kenya.
Read the full explanation →Which one of the following is a cause of acid rains?
- A.Ozone
- B.Ammonia
- C.Sulphur dioxide
- D.Carbon monoxide
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Sulphur dioxide dissolves in rainwater to form sulphuric acid, a main cause of acid rain. Burning coal and oil in power stations, smelters and vehicles releases sulphur dioxide and oxides of nitrogen into the air.
Read the full explanation →Which of the following are the major coral reef areas of India ?
1. Gulf of Kachchh
2. Gulf of Mannar
3. Lakshadweep
4. Andaman and Nicobar Islands
Select the correct answer using the code given below :
- A.1 and 3 only
- B.2 and 4 only
- C.1, 2 and 3 only
- D.1, 2, 3 and 4
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All four areas are recognised as the major coral reef areas of India. India's coral reefs lie in four main regions.
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