1. Which of the following techniques is used to generate genetically modified plants by introducing foreign genes into their genome?
a) Somatic hybridization
b) CRISPR-Cas9
c) Polyploidization
d) Genetic engineering
Answer: d) Genetic engineering
Explanation: Genetic engineering involves introducing foreign genes into a plant’s genome, often through methods like Agrobacterium-mediated transformation or biolistic particle bombardment.
2. In Marker-Assisted Selection (MAS), molecular markers are used to:
a) Induce mutations in the plant genome
b) Select desirable traits based on their genetic linkage to known markers
c) Create genetically modified organisms
d) Introduce foreign genes into a plant’s genome
Answer: b) Select desirable traits based on their genetic linkage to known markers
Explanation: MAS uses molecular markers that are linked to traits of interest, enabling breeders to select plants with those traits without needing to observe the traits directly.
3. Which of the following methods is primarily used to generate new genetic variability in a plant population by exposing seeds or tissues to mutagenic agents like chemicals or radiation?
a) Mutation breeding
b) Hybridization
c) Somatic embryogenesis
d) Genome editing
Answer: a) Mutation breeding
Explanation: Mutation breeding involves exposing plants to mutagenic agents, such as chemicals or radiation, to induce genetic variability. This can result in the appearance of new traits that may be beneficial for breeding programs.
4. Which technique uses an enzyme to induce specific, targeted changes in a plant’s DNA by cutting and repairing the genome at designated sites?
a) Transgenesis
b) Polyploidization
c) CRISPR-Cas9 gene editing
d) Protoplast fusion
Answer: c) CRISPR-Cas9 gene editing
Explanation: CRISPR-Cas9 is a precise gene-editing technique that uses an enzyme (Cas9) to create specific cuts in the plant genome at targeted locations, allowing for accurate modifications.
5. In plant breeding, the creation of polyploid plants is beneficial because it:
a) Reduces genetic diversity
b) Increases the number of chromosomes, often leading to larger plant size and improved yield
c) Allows the transfer of genes between species
d) Introduces random mutations into the genome
Answer: b) Increases the number of chromosomes, often leading to larger plant size and improved yield
Explanation: Polyploidization involves doubling the number of chromosomes in a plant, which can result in increased plant vigor, larger fruit, or enhanced yield. It is particularly used in crops like wheat and potato.
6. Which method is used to recover hybrid plants that cannot be obtained through normal fertilization due to incompatibilities or sterility, often by rescuing the embryo before it aborts?
a) Protoplast fusion
b) Embryo rescue
c) Hybridization
d) Somatic embryogenesis
Answer: b) Embryo rescue
Explanation: Embryo rescue is used to recover hybrid embryos that would normally abort or be unable to germinate due to interspecies or intergeneric incompatibilities.
7. Gene pyramiding is a technique used to:
a) Introduce a single gene for disease resistance into a plant
b) Combine multiple genes for different traits into a single genotype
c) Introduce transgenes into a plant using CRISPR-Cas9
d) Create genetically uniform plants by self-pollination
Answer: b) Combine multiple genes for different traits into a single genotype
Explanation: Gene pyramiding involves stacking multiple beneficial genes, often for disease resistance or improved performance, into one genotype, providing enhanced protection or traits.
8. Which of the following is an application of somatic hybridization in plant breeding?
a) Creating genetically modified plants by introducing foreign DNA
b) Developing hybrid plants through protoplast fusion from different species
c) Using molecular markers to select for desired traits
d) Editing specific genes using CRISPR-Cas9 technology
Answer: b) Developing hybrid plants through protoplast fusion from different species
Explanation: Somatic hybridization involves the fusion of protoplasts (plant cells without cell walls) from different species to create hybrid plants that combine traits from both parent species.
9. Which of the following is the primary goal of marker-assisted backcrossing (MABC) in plant breeding?
a) To produce transgenic plants
b) To introgress a single trait into an elite variety
c) To create genetic variability through mutagenesis
d) To achieve high-yielding hybrid plants
Answer: b) To introgress a single trait into an elite variety
Explanation: Marker-assisted backcrossing (MABC) is a technique used to introduce a specific gene (e.g., disease resistance) into an elite breeding line by repeatedly backcrossing with the parent variety while selecting for the desired trait using molecular markers.
10. Which of the following is NOT a method used for producing hybrid plants in modern breeding?
a) Protoplast fusion
b) Cross-pollination
c) Polyploidization
d) In-vitro mutagenesis
Answer: d) In-vitro mutagenesis
Explanation: In-vitro mutagenesis involves exposing plant tissues to mutagenic agents to induce mutations, but it is not a method for producing hybrid plants. Hybridization typically involves crossing different plants or species, while protoplast fusion, cross-pollination, and polyploidization are direct methods of producing hybrids.
11. Which of the following is a primary advantage of using CRISPR-Cas9 gene editing in plant breeding over traditional breeding methods?
a) It introduces random mutations into the plant genome
b) It requires no molecular markers for trait selection
c) It allows precise, targeted modifications of specific genes
d) It is not dependent on the plant’s reproductive cycle
Answer: c) It allows precise, targeted modifications of specific genes
Explanation: CRISPR-Cas9 is a precise gene-editing tool that enables breeders to make targeted changes in the plant’s genome, offering the advantage of precision compared to traditional breeding methods that rely on the inheritance of multiple genes.
12. Which of the following is a limitation of using transgenic approaches in plant breeding?
a) It is slow and labor-intensive
b) It is limited to a few crops
c) Public opposition and regulatory hurdles
d) It does not allow the transfer of traits between species
Answer: c) Public opposition and regulatory hurdles
Explanation: Transgenic approaches often face public opposition due to concerns about genetically modified organisms (GMOs), as well as regulatory challenges related to the approval and commercialization of genetically modified crops.
13. Which of the following techniques allows the creation of genetically uniform plants in a relatively short period by doubling the chromosome number?
a) Polyploidization
b) Somatic embryogenesis
c) Mutation breeding
d) CRISPR-Cas9 gene editing
Answer: a) Polyploidization
Explanation: Polyploidization involves doubling the chromosome number in a plant, often leading to genetically uniform and vigorous plants. It is commonly used to enhance traits such as yield and disease resistance.
14. Which method is used to combine desirable traits from two different species by fusing their protoplasts?
a) Hybridization
b) Somatic hybridization
c) Gene pyramiding
d) Marker-assisted selection
Answer: b) Somatic hybridization
Explanation: Somatic hybridization involves fusing the protoplasts of two different species to combine their genetic material and create hybrid plants. This method can overcome reproductive barriers between species.
15. Which of the following is a key feature of gene editing techniques, such as CRISPR, in modern plant breeding?
a) It involves the random insertion of foreign DNA into the plant genome
b) It is used to produce polyploid plants
c) It can make precise, targeted changes in the plant genome
d) It only works on plants with high genetic diversity
Answer: c) It can make precise, targeted changes in the plant genome
Explanation: Gene editing techniques like CRISPR allow for precise, targeted modifications of specific genes within the plant genome, enabling the improvement of traits without introducing foreign DNA.