Experimentation in Plant Breeding MCQs

1. Which of the following experimental designs is most commonly used in plant breeding to evaluate genetic variability among different varieties?

a) Completely Randomized Design (CRD)
b) Randomized Complete Block Design (RCBD)
c) Factorial Design
d) Split-plot Design

Answer: b) Randomized Complete Block Design (RCBD)
Explanation: RCBD is commonly used in plant breeding experiments because it helps account for variability in environmental factors. It is especially useful for comparing different varieties under uniform conditions, ensuring a balanced assessment of genetic variability.


2. What is the primary purpose of a diallel cross in plant breeding?

a) To estimate the heritability of a trait
b) To evaluate the effects of inbreeding depression
c) To study the genetic interactions among several parent varieties
d) To assess the environmental impact on crop performance

Answer: c) To study the genetic interactions among several parent varieties
Explanation: A diallel cross involves crossing multiple parent varieties with each other to study genetic interactions, such as dominance, epistasis, and general and specific combining abilities, which are important in selection for breeding programs.


3. Which of the following is NOT a key principle of the “forward breeding” strategy in plant breeding?

a) The crossing of elite varieties to combine desirable traits
b) The use of hybrid vigor to improve yield
c) The introduction of alleles from wild species for disease resistance
d) The selection of the best-performing individuals for self-pollination

Answer: d) The selection of the best-performing individuals for self-pollination
Explanation: Forward breeding focuses on crossing elite varieties and improving desirable traits, often using hybrid vigor. It generally avoids self-pollination as it can lead to inbreeding depression. Selection usually involves choosing the best hybrids, not self-pollinated individuals.


4. Which of the following experimental techniques is used in plant breeding to evaluate the combining ability of two parent plants?

a) Mutation breeding
b) Gene pyramiding
c) Heterosis (hybrid vigor) testing
d) G × E (genotype × environment) interaction studies

Answer: c) Heterosis (hybrid vigor) testing
Explanation: Heterosis, or hybrid vigor, is used to evaluate the combining ability of two parent plants. It assesses whether the hybrid offspring outperform the parent varieties in traits such as yield, size, or disease resistance.


5. In a plant breeding program, the term “heterosis” refers to:

a) The increase in genetic uniformity in the offspring
b) The loss of desirable traits in the offspring
c) The hybrid vigor or increased performance of hybrids compared to parents
d) The genetic improvement achieved by self-pollination

Answer: c) The hybrid vigor or increased performance of hybrids compared to parents
Explanation: Heterosis, or hybrid vigor, is the phenomenon where hybrid plants perform better than their parents, particularly in traits like yield, growth rate, and resistance to stress.


6. What is the main goal of using a recurrent selection method in plant breeding?

a) To combine desirable traits from different varieties into one hybrid
b) To develop a population with increased genetic diversity
c) To improve a population by selecting for specific traits over multiple generations
d) To assess the response of a population to environmental changes

Answer: c) To improve a population by selecting for specific traits over multiple generations
Explanation: Recurrent selection is a method used to improve a population by selecting individuals that exhibit desired traits. It involves repeated cycles of selection and intercrossing over several generations to enhance the trait of interest.


7. Which of the following methods is most commonly used to induce mutations in plants for breeding purposes?

a) Cross-pollination
b) Hybridization
c) Chemical mutagenesis
d) Gene editing

Answer: c) Chemical mutagenesis
Explanation: Chemical mutagenesis, such as using chemicals like EMS (ethyl methanesulfonate), is commonly used in plant breeding to induce mutations that may lead to beneficial traits, such as disease resistance or increased yield.


8. In a breeding program, what is the purpose of backcrossing?

a) To increase genetic diversity in the breeding population
b) To introduce a specific trait from a donor parent into a recurrent parent
c) To evaluate the effects of environment on plant traits
d) To test hybrid vigor between two parent lines

Answer: b) To introduce a specific trait from a donor parent into a recurrent parent
Explanation: Backcrossing is a method used to introgress a desired trait from a donor parent into a recurrent parent by crossing the hybrid offspring back to the recurrent parent multiple times. This helps retain the genetic background of the recurrent parent while introducing the trait.


9. Which of the following is the primary advantage of using molecular markers in plant breeding?

a) To reduce the need for field trials
b) To identify and select for traits that are difficult to observe phenotypically
c) To improve the efficiency of traditional crossbreeding
d) To create genetically uniform populations

Answer: b) To identify and select for traits that are difficult to observe phenotypically
Explanation: Molecular markers allow breeders to identify specific genes or alleles associated with desirable traits, which is especially useful for traits that are difficult or time-consuming to observe phenotypically.


10. In a plant breeding experiment, what is the primary purpose of using a control group?

a) To measure the effect of different experimental treatments
b) To prevent contamination of the experiment by external factors
c) To ensure that all experimental treatments are conducted under identical conditions
d) To measure the environmental impact of breeding methods

Answer: a) To measure the effect of different experimental treatments
Explanation: A control group is used in experiments to compare the effect of different experimental treatments. It is often subjected to standard conditions or no treatment, allowing for a baseline measurement to assess the impact of the experimental treatments.


11. What is the primary focus of “mutation breeding” in plant breeding programs?

a) To cross different plant varieties and observe hybrid performance
b) To introduce new genetic variations by inducing mutations
c) To select plants based on phenotypic traits
d) To develop inbred lines through repeated self-pollination

Answer: b) To introduce new genetic variations by inducing mutations
Explanation: Mutation breeding involves the use of physical or chemical agents to induce mutations in plant genomes, thereby creating genetic variations that can be exploited for improving traits like yield, disease resistance, and stress tolerance.


12. Which of the following is the most common method for creating hybrid varieties in crop breeding?

a) Using genetic engineering to insert foreign genes
b) Cross-pollination between two genetically different parental lines
c) Inbreeding between genetically similar individuals
d) Hybridization using molecular markers

Answer: b) Cross-pollination between two genetically different parental lines
Explanation: The most common method for creating hybrid varieties is cross-pollination between two genetically different parental lines. This method leverages hybrid vigor (heterosis), where the hybrid offspring exhibit superior traits compared to the parents.


13. What is the main objective of using the “single seed descent” method in plant breeding?

a) To maintain genetic variability in the breeding population
b) To rapidly advance generations while maintaining genetic integrity
c) To develop genetically uniform populations
d) To create hybrids with increased heterosis

Answer: b) To rapidly advance generations while maintaining genetic integrity
Explanation: The single seed descent method allows rapid advancement of generations by selecting a single seed from each plant in the population and growing it to produce the next generation. This method helps in quickly fixing desirable traits while maintaining the genetic integrity of the population.


14. Which of the following is a disadvantage of using inbreeding in plant breeding?

a) It can lead to a higher genetic diversity in the offspring
b) It can increase the risk of inbreeding depression, where traits like vigor or fertility decrease
c) It results in immediate hybrid vigor
d) It increases the heterozygosity in the population

Answer: b) It can increase the risk of inbreeding depression, where traits like vigor or fertility decrease
Explanation: Inbreeding, which involves mating closely related plants, can result in inbreeding depression, where the genetic uniformity leads to a loss of vigor, fertility, or overall plant performance.


15. Which of the following statistical methods is commonly used in plant breeding to estimate the heritability of a trait?

a) Analysis of Variance (ANOVA)
b) Regression analysis
c) Correlation analysis
d) Principal Component Analysis (PCA)

Answer: a) Analysis of Variance (ANOVA)
Explanation: Analysis of Variance (ANOVA) is commonly used in plant breeding to partition the total variation into genetic and environmental components, helping to estimate the heritability of a trait.

Leave a Reply

Your email address will not be published. Required fields are marked *