Tissue culture techniques: organogenesis, embryogenesis, synthetic seeds MCQs With Answer

Introduction: This quiz set focuses on advanced tissue culture techniques—organogenesis, embryogenesis and synthetic seeds—tailored for M.Pharm students studying Medicinal Plant Biotechnology (MPG 201T). Questions probe practical and theoretical aspects: explant selection, plant growth regulators, direct vs indirect pathways, stages of somatic embryos, encapsulation materials and methods, maturation and storage strategies, and common problems such as somaclonal variation and low conversion rates. Designed to reinforce laboratory decision-making and exam preparation, the MCQs emphasize mechanisms, protocols and applications relevant to medicinal plant propagation, germplasm conservation and scalable production of high-quality plant material for pharmaceutical research.

Q1. What is the most accurate definition of a synthetic seed in plant tissue culture?

• Encapsulated zygotic embryo only
• Encapsulated somatic embryo or other regenerative propagule capable of developing into a plantlet
• Seeds produced by chemical synthesis mimicking natural seed components
• Genetically engineered seeds with synthetic coatings

Correct Answer: Encapsulated somatic embryo or other regenerative propagule capable of developing into a plantlet

Q2. Which statement best distinguishes direct organogenesis from indirect organogenesis?

• Direct organogenesis requires callus formation before organ initiation
• Indirect organogenesis occurs directly from explant tissue without callus
• Direct organogenesis forms organs directly from the explant without an intervening callus phase
• Indirect organogenesis uses only cytokinin and no auxin

Correct Answer: Direct organogenesis forms organs directly from the explant without an intervening callus phase

Q3. Which plant growth regulator is most commonly used to induce somatic embryogenesis in many species?

• Benzylaminopurine (BAP)
• Gibberellic acid (GA3)
• 2,4‑Dichlorophenoxyacetic acid (2,4‑D)
• Abscisic acid (ABA)

Correct Answer: 2,4‑Dichlorophenoxyacetic acid (2,4‑D)

Q4. Which hormonal balance typically promotes shoot organogenesis in explant cultures?

• High auxin : low cytokinin
• Equal auxin and cytokinin
• Low auxin : high cytokinin
• No hormones required

Correct Answer: Low auxin : high cytokinin

Q5. What is secondary somatic embryogenesis?

• Somatic embryos arising directly from zygotic embryos
• Somatic embryos developed from callus only
• Formation of new somatic embryos from existing somatic embryos or their tissues
• Somatic embryos that fail to mature and form callus

Correct Answer: Formation of new somatic embryos from existing somatic embryos or their tissues

Q6. Which combination is most commonly used for forming the alginate beads in synthetic seed production?

• Polyvinyl alcohol + magnesium chloride
• Sodium alginate + calcium chloride
• Agarose + potassium nitrate
• Gelatin + ammonium sulfate

Correct Answer: Sodium alginate + calcium chloride

Q7. What is the principal role of abscisic acid (ABA) during somatic embryo development?

• Initiation of callus formation
• Promotion of shoot bud differentiation
• Maturation of embryos and induction of desiccation tolerance
• Breaking seed dormancy

Correct Answer: Maturation of embryos and induction of desiccation tolerance

Q8. Which is a major technical limitation frequently encountered with synthetic seeds in commercial deployment?

• Unlimited long-term storage without treatment
• High conversion frequency universally across species
• Low plantlet conversion rates and reduced storage viability for many species
• Complete genetic uniformity among regenerants

Correct Answer: Low plantlet conversion rates and reduced storage viability for many species

Q9. What is the goal of the encapsulation‑dehydration approach when preparing propagules for long-term storage?

• Increase water content to improve metabolism during storage
• Reduce water content to enhance tolerance to low-temperature storage or cryopreservation
• Eliminate the need for encapsulation polymer
• Promote rapid germination at ambient temperature

Correct Answer: Reduce water content to enhance tolerance to low-temperature storage or cryopreservation

Q10. Which light condition is commonly used during the induction phase of somatic embryogenesis for many species?

• Continuous bright light
• Photoperiod of 16h light / 8h dark
• Complete darkness or low light during early induction
• Intermittent ultraviolet exposure

Correct Answer: Complete darkness or low light during early induction

Q11. How is “conversion frequency” defined in the context of synthetic seeds?

• Percentage of beads that remain intact after storage
• Percentage of encapsulated propagules that develop into viable plantlets
• Time required for plantlets to reach maturity
• Number of somatic embryos formed per callus

Correct Answer: Percentage of encapsulated propagules that develop into viable plantlets

Q12. Polyethylene glycol (PEG) is often applied during somatic embryo maturation to:

• Provide mineral nutrients
• Create osmotic stress that promotes maturation and desiccation tolerance
• Act as a gelling agent for bead formation
• Replace sucrose as an energy source

Correct Answer: Create osmotic stress that promotes maturation and desiccation tolerance

Q13. Which explant source typically exhibits the highest embryogenic potential in many crop and medicinal species?

• Mature leaves from old plants
• Root hairs from field-grown plants
• Immature zygotic embryos or young meristematic tissues
• Fully lignified stem segments

Correct Answer: Immature zygotic embryos or young meristematic tissues

Q14. Which culture practice most increases the risk of somaclonal variation in regenerated plants?

• Short-term direct organogenesis without callus
• Regeneration via protoplast fusion only
• Prolonged callus culture and repeated subculturing prior to regeneration
• Using only meristem tip cultures with no hormones

Correct Answer: Prolonged callus culture and repeated subculturing prior to regeneration

Q15. Which storage strategy improves short- to mid-term viability of many synthetic seeds?

• Storage at room temperature with high moisture
• Deep-freeze without dehydration
• Controlled desiccation followed by low temperature storage (e.g., 4°C)
• Exposure to continuous light at 25°C

Correct Answer: Controlled desiccation followed by low temperature storage (e.g., 4°C)

Q16. Which analytical technique is commonly used to verify genetic fidelity of plants regenerated from somatic embryos or synthetic seeds?

• High-performance liquid chromatography (HPLC) only
• Random Amplified Polymorphic DNA (RAPD) or SSR marker analysis
• Visual comparison of leaf color only
• Soil nutrient analysis

Correct Answer: Random Amplified Polymorphic DNA (RAPD) or SSR marker analysis

Q17. Which application is NOT a typical advantage of synthetic seed technology?

• Large-scale clonal propagation of elite genotypes
• Facilitated exchange of germplasm without whole plants
• Guaranteed elimination of pathogens from mother plants
• Temporary storage and distribution of transgenic material

Correct Answer: Guaranteed elimination of pathogens from mother plants

Q18. Which sequence correctly describes the classical morphological stages of somatic embryo development?

• Cotyledon → Torpedo → Heart → Globular
• Globular → Heart → Torpedo → Cotyledon
• Torpedo → Cotyledon → Heart → Globular
• Callus → Shoot → Root → Plantlet

Correct Answer: Globular → Heart → Torpedo → Cotyledon

Q19. Cytokinins primarily influence which process during organogenesis?

• Root elongation and lateral root formation only
• Induction of somatic embryos by osmotic stress
• Stimulation of cell division and shoot bud initiation
• Induction of desiccation tolerance in embryos

Correct Answer: Stimulation of cell division and shoot bud initiation

Q20. For long-term preservation of synthetic seeds from recalcitrant (desiccation‑sensitive) species, the preferred conservation method is:

• Room temperature storage in nutrient gel
• Refrigeration at 4°C without dehydration
• Cryopreservation in liquid nitrogen following appropriate encapsulation‑dehydration or vitrification
• Continuous light incubation at low humidity

Correct Answer: Cryopreservation in liquid nitrogen following appropriate encapsulation‑dehydration or vitrification

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