Plant Breeding - methods of crop improvement: introduction, selection, heterosis, hybridization, polyploidy, mutation breeding - Question Bank

1. Which of the following is an example of an allopolyploid?
A) A plant with 4 sets of chromosomes from the same species
B) A plant with 6 sets of chromosomes from the same species
C) Triticale (a hybrid of wheat and rye)
D) A plant with 3 sets of chromosomes from the same species
2. The process of inducing mutations using agents like gamma rays or EMS is part of:
A) Hybridization
B) Selection
C) Mutation Breeding
D) Introduction
3. Which of the following is a key characteristic of heterosis?
A) Increased homozygosity
B) Superior performance of F1 hybrids over parents
C) Reduced genetic variation
D) Sterility of offspring
4. What is the main goal of using selection in plant breeding programs?
A) To create genetic mutations
B) To increase the ploidy level
C) To isolate and propagate individuals with desirable traits
D) To induce heterosis
5. The introduction of a variety developed in one agro-climatic zone into another agro-climatic zone is termed:
A) Introduction
B) Acclimatization
C) Naturalization
D) Adaptation
6. Which method is useful for transferring a specific desirable gene from a wild relative into an elite cultivated variety?
A) Mutation Breeding
B) Polyploidy
C) Backcrossing
D) Mass Selection
7. A plant with an even number of chromosome sets, such as 4n or 6n, generally has:
A) Lower fertility
B) Higher fertility compared to odd-numbered polyploids
C) No viable seeds
D) Reduced vigor
8. Which type of hybridization is essential for creating new species or overcoming reproductive isolation barriers between species?
A) Intervarietal hybridization
B) Interspecific hybridization
C) Intergeneric hybridization
D) Intraspecific hybridization
9. What is the genetic basis of heterosis?
A) Complete dominance of desirable alleles in homozygous state
B) Overdominance (heterozygote superiority) and/or epistasis
C) Accumulation of recessive deleterious alleles
D) Increased homozygosity
10. The selection of individual plants that are genetically uniform and breed true is called:
A) Mass selection
B) Progeny selection
C) Pure-line selection
D) Recurrent selection
11. A plant breeding method that directly uses induced or spontaneous genetic changes is:
A) Hybridization
B) Selection
C) Mutation Breeding
D) Introduction
12. Which of the following is a disadvantage of polyploidy breeding?
A) Often leads to larger plant size
B) Can result in reduced fertility in odd-numbered polyploids (e.g., triploids)
C) Increases genetic diversity
D) Can be used to overcome interspecific hybridization barriers
13. What is the main objective of developing hybrid varieties?
A) To achieve uniformity in the offspring
B) To exploit heterosis for increased yield and vigor
C) To increase chromosome number
D) To introduce genes from wild relatives
14. The process of selecting desirable genotypes from a segregating population and maintaining records of their ancestry is known as:
A) Mass selection
B) Pedigree selection
C) Pure-line selection
D) Bulk selection
15. Which chemical is commonly used to induce polyploidy by inhibiting spindle formation during mitosis?
A) Ethyleneimine
B) Colchicine
C) EMS
D) Gamma rays
16. Allopolyploidy results from:
A) Chromosome doubling within a species
B) The fusion of gametes from different species followed by chromosome doubling
C) The spontaneous mutation of chromosomes
D) The loss of chromosomes
17. What is the primary challenge in interspecific or intergeneric hybridization?
A) High probability of success
B) Lack of genetic variation
C) Cross-incompatibility and reduced fertility of hybrids
D) Rapid development of stable varieties
18. The phenomenon where inbred lines, when crossed, produce offspring with superior traits is the basis of:
A) Polyploidy breeding
B) Mutation breeding
C) Hybridization for heterosis breeding
D) Introduction
19. Which selection method involves selecting individual plants based on their own performance, assuming a relatively uniform population?
A) Progeny selection
B) Mass selection
C) Pedigree selection
D) Recurrent selection
20. What is the term for a variety that is introduced from another country and grown successfully in a new environment?
A) Native variety
B) Exotic variety
C) Indigenous variety
D) Hybrid variety
21. The process of crossing plants from different genera is called:
A) Interspecific hybridization
B) Intervarietal hybridization
C) Intergeneric hybridization
D) Intrageneric hybridization
22. Which polyploid has 6 sets of chromosomes (6n)?
A) Diploid
B) Tetraploid
C) Hexaploid
D) Octoploid
23. What is the main advantage of using mutation breeding for creating new varieties?
A) It is a highly predictable method.
B) It can create new alleles and genetic variation.
C) It always results in superior hybrids.
D) It is faster than hybridization.
24. The term 'hybrid vigor' is synonymous with:
A) Inbreeding depression
B) Apomixis
C) Heterosis
D) Polyploidy
25. Recurrent selection is a method primarily used for:
A) Developing pure lines
B) Increasing homozygosity
C) Improving quantitative traits by accumulating favorable alleles
D) Creating polyploids
26. What is the primary challenge in the 'Introduction' method of crop improvement?
A) Low genetic variability
B) Adaptation to new environmental conditions and potential pest/disease introduction
C) Difficulty in controlling pollination
D) High cost of inducing mutations
27. Which of the following is an example of a physical mutagen?
A) Ethyl methanesulfonate (EMS)
B) Colchicine
C) Gamma rays
D) Nitrous acid
28. An organism with four sets of chromosomes (4n) is called:
A) Diploid
B) Triploid
C) Tetraploid
D) Hexaploid
29. Backcrossing is a technique used to:
A) Introduce a single gene into an otherwise elite genetic background
B) Combine multiple desirable traits from different parents
C) Induce polyploidy
D) Increase genetic diversity rapidly
30. The phenomenon where the F1 hybrid is less vigorous than its parents is called:
A) Heterosis
B) Hybrid vigor
C) Negative heterosis or anti-heterosis
D) Overdominance
31. Which type of selection is based on the performance of the progeny of individual plants?
A) Mass selection
B) Pure-line selection
C) Progeny selection
D) Family selection
32. What is a 'check variety' used for in crop improvement?
A) To induce mutations
B) To compare the performance of new varieties
C) To maintain genetic purity
D) To measure heterosis
33. Which of the following is a major advantage of mutation breeding?
A) It can create new gene combinations not possible through hybridization.
B) It always results in increased yield.
C) It is a very rapid method for crop improvement.
D) It requires less genetic diversity.
34. Autopolyploidy refers to polyploidy arising from:
A) The fusion of gametes from different species
B) The doubling of the chromosome set within the same species
C) The addition of chromosomes from a different genus
D) The loss of a chromosome set
35. Crossing between plants of different species within the same genus is known as:
A) Intervarietal hybridization
B) Interspecific hybridization
C) Intergeneric hybridization
D) Intraspecific hybridization
36. What is 'hybrid breakdown' in the context of heterosis?
A) The loss of heterotic effect in subsequent generations (F2 onwards)
B) The failure of the hybrid to germinate
C) The reduced fertility of the F1 hybrid
D) The increased susceptibility of the hybrid to diseases
37. Mass selection is a type of selection where:
A) Individual plants are selected based on phenotype
B) A large population is selected based on a common desirable trait
C) Selection is based on performance of progenies
D) Selection is done in multiple generations
38. The introduction of a pre-existing improved variety into a new region without any genetic modification is called:
A) Acclimatization
B) Introduction
C) Naturalization
D) Adaptation
39. Which mutagen is commonly used to induce point mutations in plants?
A) Gamma rays
B) Ethyleneimine (EI)
C) X-rays
D) Ultraviolet radiation
40. A plant with three sets of chromosomes (3n) is an example of:
A) Monoploid
B) Diploid
C) Triploid
D) Tetraploid
41. Which type of hybridization involves crossing between plants of the same species but different varieties?
A) Intervarietal hybridization
B) Interspecific hybridization
C) Intergeneric hybridization
D) Backcrossing
42. In heterosis, the superior performance of the F1 hybrid is often attributed to:
A) Dominance
B) Epistasis
C) Overdominance and/or epistasis
D) Recessive gene action
43. What is the primary goal of selection in plant breeding?
A) To create new genetic combinations
B) To increase chromosome number
C) To isolate and propagate superior genotypes
D) To induce random genetic changes
44. Which method involves bringing a variety or species from a different region or country to a new area for cultivation?
A) Introduction
B) Selection
C) Heterosis
D) Mutation Breeding
45. An increase in the number of chromosome sets in an organism, often leading to larger size and vigor, is termed as:
A) Heterosis
B) Polyploidy
C) Selection
D) Hybridization
46. The deliberate alteration of the genetic makeup of a plant using physical or chemical agents to induce mutations is called:
A) Hybridization
B) Polyploidy
C) Introduction
D) Mutation Breeding
47. What is the phenomenon where the F1 generation of a cross between two genetically dissimilar parents shows significantly enhanced vigor and yield compared to either parent?
A) Polyploidy
B) Mutation Breeding
C) Heterosis
D) Introduction
48. The process of selecting individual plants with superior traits from a mixed population for further propagation is known as:
A) Introduction
B) Hybridization
C) Selection
D) Heterosis
49. Which method of crop improvement involves introducing desirable genes from one variety into another through controlled pollination?
A) Hybridization
B) Selection
C) Mutation Breeding
D) Polyploidy
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