The topic of hybridisation is one of the most important topics of plant tissue culture in the life sciences. It is one of the most scoring topics in exams like GATE and CSIR NET. Even though this is not such a vast topic but it is definitely one of the most conceptual topics. We have highly researched the topics and got the best MCQs for the students preparing for the exams, and for the ones who want to have the best of their time by doing last-minute revisions to cover all the topics of the vast syllabus prescribed. All those candidates who want to secure their seats in any of the upcoming examinations may go through these questions without waiting any further.
Which plant species contributed resistance against Plasmodiophora brassicae?
A) N. tabacum
B) B. nigra
C) N. repanda
D) N. plumbaginifolia
Correct Answer: (B) B. nigra
In resistant hybrids developed through somatic fusion, what type of chromosome variation was mainly observed?
A) No variation
B) Great inter- and intra-clonal variation
C) Only stable chromosome number
D) Limited variation in single clones
Correct Answer: (B) Great inter- and intra-clonal variation
The presence of cells with different chromosome numbers in one root suggests what biological process?
A) Stable inheritance
B) Mutation only
C) Chromosome elimination continues after regeneration
D) DNA replication error
Correct Answer: (C) Chromosome elimination continues after regeneration
Who successfully recovered asymmetric hybrids by fusing N. tabacum protoplasts with irradiated N. repanda cells?
A) Menczel
B) Bates
C) Wolters
D) Ramulu
Correct Answer: (B) Bates
Which selectable marker was used for identifying asymmetric hybrids involving N. repanda transformation?
A) Kanamycin resistance
B) Ampicillin resistance
C) Streptomycin resistance
D) Hygromycin resistance
Correct Answer: (A) Kanamycin resistance
When inoculated with TMV, which special response did hybrids from N. repanda show?
A) Immunity to fungi
B) Complete sterility
C) Hypersensitivity to TMV
D) Resistance to antibiotics
Correct Answer: (C) Hypersensitivity to TMV
The asymmetric hybrids produced viable seeds when backcrossed with which species?
A) N. repanda
B) N. tabacum
C) N. glutinosa
D) B. nigra
Correct Answer: (B) N. tabacum
From which donor species was TMV hypersensitivity transferred into N. tabacum through asymmetric hybridization?
A) N. repanda
B) B. nigra
C) N. plumbaginifolia
D) N. glutinosa
Correct Answer: (D) N. glutinosa
In asymmetric hybridization, the extent of donor genome elimination varies depending on which important factor?
A) Irradiation dose only
B) Selection agent only
C) Species involved in fusion
D) Type of chloroplast present
Correct Answer: (C) Species involved in fusion
What type of hybrids are formed by the Fusion of N. plumbaginifolia with irradiated N. tabacum?
A) Normal fertile hybrids
B) Sterile diploids
C) Cybrids having nuclear and plastid DNA
D) Polyploid hybrids only
Correct Answer: (C) Cybrids having nuclear and plastid DNA
At what irradiation dose were cybrids successfully produced in the N. plumbaginifolia and N. tabacum experiment?
A) 10 Gy
B) 50 Gy
C) 100 Gy
D) 500 Gy
Correct Answer: (B) 50 Gy
Fusion of irradiated Solanum tuberosum with Lycopersicon esculentum produced what significant observation?
A) Stable, fertile hybrids
B) No hybrid lacking potato DNA
C) Complete chromosome elimination
D) Fully resistant plants
Correct Answer: (B) No hybrid lacking potato DNA
Even after exposure to 500 Gy irradiation, what component of the potato remained uneliminated in fusion hybrids?
A) Mitochondria
B) Cytoplasm
C) Potato chromosomes
D) Chloroplasts
Correct Answer: (C) Potato chromosomes
Which approach is used to achieve partial donor genome transfer for creating asymmetric hybrids?
A) Using microprotoplasts with few chromosomes
B) Irradiating chloroplasts directly
C) Treating only mitochondria
D) Removing the whole nuclear genome
Correct Answer: (A) Using microprotoplasts with few chromosomes
What treatment is used to induce micronuclei formation for preparing microprotoplasts?
A) Antibiotics
B) Growth hormones
C) Antimicrotubule agents
D) Irradiated water
Correct Answer: (C) Antimicrotubule agents
Which nuclear structures are specifically manipulated to obtain microprotoplasts?
A) Chloroplasts
B) Micronuclei
C) Ribosomes
D) Mitochondria
Correct Answer: (B) Micronuclei
What major plant response did hybrids show when infected with TMV during Bates’ experiment?
A) Strong immunity
B) Hypersensitivity response
C) Tolerance only
D) No reaction
Correct Answer: (B) Hypersensitivity response
Bates recovered asymmetric hybrids by selecting plants resistant to which antibiotic agent?
A) Streptomycin
B) Kanamycin
C) Penicillin
D) Rifampicin
Correct Answer: (B) Kanamycin
Which crop combination failed to produce any hybrid lacking potato DNA, even with high irradiation levels?
A) N. tabacum × N. repanda
B) N. plumbaginifolia × N. tabacum
C) S. tuberosum × L. esculentum
D) B. nigra × Brassica hybrids
Correct Answer: (C) S. tuberosum × L. esculentum
Hybrids that appear similar to N. tabacum but carry some donor traits from N. repanda are called?
A) Stable hybrids
B) Asymmetric hybrids
C) Sterile hybrids
D) Symmetric hybrids
Correct Answer: (B) Asymmetric hybrids
What biological process is indicated when chromosome elimination continues even after full plant regeneration?
A) Stable mutation
B) Hybrid vigor
C) Somatic hybrid instability
D) DNA repair mechanism
Correct Answer: (C) Somatic hybrid instability
What genetic combination was observed in cybrids obtained by Menczel et al. (1982)?
A) Potato nuclear DNA and tomato mitochondria
B) N. plumbaginifolia nuclear DNA and N. tabacum chloroplasts
C) N. repanda nuclear DNA and kanamycin chloroplasts
D) N. glutinosa nuclear DNA and TMV DNA
Correct Answer: (B) N. plumbaginifolia nuclear DNA and N. tabacum chloroplasts
What is the main purpose of using γ-irradiation in protoplast fusion experiments of asymmetric hybrids?
A) Increase chlorophyll production
B) Induce chromosome elimination
C) Enhance seed germination
D) Improve plant height
Correct Answer: (B) Induce chromosome elimination
The ability of largely sterile hybrids to produce viable seeds after backcrossing shows what advantage?
A) Complete sterility
B) Genetic compatibility with N. tabacum
C) Incomplete dominance
D) Reduced adaptability
Correct Answer: (B) Genetic compatibility with N. tabacum
Who demonstrated successful transfer of TMV hypersensitivity from N. glutinosa to N. tabacum through hybridization?
A) Menczel
B) Wolters
C) Ramulu
D) Bates
Correct Answer: (D) Bates
