This set of Class 12 Biology Chapter 9 Multiple Choice Questions & Answers (MCQs) focuses on “Plant Breeding for Disease Resistance”.
1. Which of the following is not responsible for crop losses?
a) Fungi
b) Bacteria
c) Virus
d) Earthworm
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Explanation: A wide range of fungal, bacterial and viral pathogens, affect the yield of cultivated crop species, especially in tropical climates. Crop losses can often be significant, up to 20-30 per cent, or sometimes even total.
2. Which of the following term is used for organisms which are attacked by pathogens?
a) Crop
b) Variety
c) Host
d) Susceptible host
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Explanation: The term susceptible host is used for those organisms which are not resistant to the pathogens but are attacked and harmed by pathogens. The susceptible individuals in which a disease is caused by a pathogen is called as host.
3. How is the resistance of the host plant towards a pathogen determined?
a) By looking at the leaves
b) By researching the seed
c) By studying the genetic constitution of the plant
d) By cutting the stem
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Explanation: Resistance of the host plant is the ability to prevent the pathogen from causing disease and is determined by the genetic constitution of the host plant. Before breeding is undertaken, it is important to know about the causative organism and the mode of transmission.
4. How does the development of disease-resistant plants enhance food production?
a) Reduce the dependence on fertilizers
b) Reduce the dependence of fungicides
c) Reduce the dependence of water
d) Reduce the dependence of air
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Explanation: When there are crop losses, then breeding and development of cultivars resistant to disease enhance food production. This also helps reduce the dependence on the use of fungicides and bacteriocides.
5. Which of the following is not a sequential step of breeding disease resistance crop?
a) Harvesting crops
b) Screening germplasm
c) The hybridisation of selected parents
d) Selection and evaluation of hybrids
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Explanation: The various sequential steps of breeding disease resistance crop are screening germplasm for resistance sources, hybridisation of selected parents, selection and evaluation of the hybrids and testing and release of new varieties.
6. Which of the following is a variety of wheat crop?
a) Pusa Swarnim
b) Pusa Shubhra
c) Himgiri
d) Pusa Komal
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Explanation: Himgiri is the variety of Wheat crop. Pusa Swarnim, Pusa Shubhra and Pusa Komal are the varieties of Brassica, Cauliflower and Cowpea respectively.
7. Which of the following crops is resistant to the chilly mosaic virus?
a) Cowpea
b) Cauliflower
c) Chilli
d) Brassica
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Explanation: Chilli crop is resistant to chilly mosaic virus, tobacco mosaic virus and leaf curl disease. Cowpea is resistant to bacterial blight. Cauliflower is resistant to black rot and curl blight black rot disease. Brassica is resistant to white rust disease.
8. Availability of a limited number of disease resistance genes constrains conventional breeding practices.
a) True
b) False
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Explanation: Conventional breeding is often constrained by the availability of a limited number of disease resistance genes that are present and identified in various crop varieties or wild relatives. Inducing mutations in plants through diverse means and then screening the plant materials for resistance sometimes leads to desirable genes being identified.
9. What is a mutation?
a) Change in DNA
b) Change in the entire genetic makeup of the organism
c) Change in RNA
d) Change in base sequence within genes
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Explanation: Mutation is the process by which genetic variations are created through changes in the base sequence within genes resulting in the creation of a new character or trait not found in the parental type.
10. Which of the following is used to induce mutations in plants?
a) Radiations
b) Water
c) Virus
d) Leaves
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Explanation: It is possible to induce mutations artificially in plants through the use of chemicals or radiations (gamma radiations), and selecting and using the plants that have the desired character as a source of breeding. This process is known as mutation breeding.
11. In mung bean, resistance to chilly mosaic virus and powdery mildew were induced by mutations.
a) True
b) False
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Explanation: In mung bean, resistance to yellow mosaic virus and powdery mildew were induced by mutations. This process involves the source of resistance genes that are in the same crop species, which has to be bred for disease resistance, or in a related wild species.
12. Resistance to the yellow mosaic virus in bhindi (Abelmoschus esculentus) resulted in a new variety called _________
a) Pusa Sadabahar
b) Parbhani Kranti
c) Himgiri
d) Pusa Shubhra
View Answer
Explanation: Resistance to the yellow mosaic virus in bhindi (Abelmoschus esculentus) was transferred from a wild species and resulted in a new variety of Abelmoschus esculentus called Parbhani Kranti. Transfer of resistance genes is achieved by sexual hybridisation between the target and the source plant followed by selection.
Sanfoundry Global Education & Learning Series – Biology – Class 12.
To practice all chapters and topics of class 12 Biology, here is complete set of 1000+ Multiple Choice Questions and Answers.
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- Practice Class 11 - Biology MCQs
- Practice Class 12 - Physics MCQs
- Practice Class 12 - Chemistry MCQs
- Check Class 12 - Biology Books
- Practice Class 12 - Mathematics MCQs
