Question 1

Synthetic seeds (encapsulated somatic embryos): which statement is NOT true about their practical properties and handling?

Accepted Answer

Introduction / Context: Synthetic seeds are somatic embryos encapsulated in a protective gel. They aim to combine advantages of micropropagation with seed-like handling. However, their performance differs from botanical seeds, especially for storage longevity and field establishment. Given Data / Assumptions: Synthetic seeds are living tissue systems without natural protective seed coats. Encapsulation matrices (e.g., alginate) protect and aid handling. Viability during storage depends on moisture, temperature, and embryo physiology. Concept / Approach: True orthodox seeds tolerate drying and long storage at low temperature. Many somatic embryos are recalcitrant by nature, sensitive to drying and freezing, so long-term storage at room conditions is unreliable. Therefore, blanket claims of a full year of storage without loss are not generally accurate without specialized cryopreservation protocols. Step-by-Step Solution: Compare natural seed longevity to somatic embryo physiology.Note that encapsulation aids handling but does not inherently confer long dormancy.Identify the statement asserting year-long storage without losses; this overgeneralizes and is typically untrue. Verification / Alternative check: Published work frequently reports decreased germination after weeks to months unless cold, humidity control, or cryogenic methods are used; routine one-year storage is not guaranteed. Why Other Options Are Wrong: B: Handling is indeed easier in lab workflows. C: Some species allow direct sowing in optimized substrates. D: Hardening is often needed to acclimatize plantlets. E: Asepsis is commonly required to prevent microbial loss. Common Pitfalls: Equating synthetic seeds with orthodox seeds; ignoring species- and protocol-specific variability. Final Answer: Can be stored for a year without the loss of valuable traits or viability

Question 2

Seed biology: “Recalcitrant seeds” are best described as which of the following with respect to drying and low-temperature storage?

Accepted Answer

Introduction / Context: Seeds are often classified as orthodox or recalcitrant based on their tolerance to desiccation and storage conditions. Understanding this distinction is crucial in conservation, genebanking, and nursery operations. Given Data / Assumptions: Orthodox seeds tolerate drying and can be stored at low moisture and temperature for long periods. Recalcitrant seeds are typically from tropical or subtropical species. Cellular damage in recalcitrant seeds occurs on dehydration and freezing. Concept / Approach: Recalcitrant seeds remain metabolically active, have high moisture content, and lack mechanisms to survive desiccation. Ice crystal formation at subzero temperatures and membrane damage during water loss reduce viability, making conventional seed banking unsuitable. Step-by-Step Solution: Identify the class: recalcitrant = desiccation-sensitive.Relate to storage: drying/freezing triggers lethal damage.Therefore select the option stating they are killed by drying and freezing. Verification / Alternative check: Species such as cocoa, mango, and many forest trees exhibit sharp viability declines upon desiccation or low-temperature storage. Why Other Options Are Wrong: A/D: Opposite of the definition; recalcitrant seeds are not resistant and are affected. C: While sensitivity varies in degree, the class is defined by sensitivity, not resistance. E: Irrelevant to the standard classification. Common Pitfalls: Assuming all seeds store like cereals; overlooking moisture content parameters leads to viability loss. Final Answer: Killed by drying and freezing temperatures

Question 3

In synthetic seed technology, preserved somatic embryoids (after encapsulation or storage) are commonly termed:

Accepted Answer

Introduction / Context: Synthetic seed technology packages somatic embryos into bead-like units that mimic true seeds for handling, storage, and sowing. The terminology helps standardize communication between labs and nurseries. Given Data / Assumptions: Somatic embryos are produced via tissue culture (not from fertilization). Encapsulation uses hydrogels such as sodium alginate–calcium chloride systems. Objective: seed-like handling and potential direct planting. Concept / Approach: Once embryoids are encapsulated or preserved for later use, they are referred to as synthetic seeds. The term emphasizes their functional analogy to zygotic seeds while acknowledging their somatic origin and artificial coating. Step-by-Step Solution: Define embryoid storage/encapsulation output.Map common nomenclature used in literature and practice.Select “Synthetic seeds” as the accepted term. Verification / Alternative check: Protocols across horticultural species use “synthetic seeds” to denote encapsulated somatic embryos; no equivalent natural seed coat is present. Why Other Options Are Wrong: B: “Semi-synthetic” is not standard. C/D: Natural or fermented seeds do not describe tissue-culture-derived embryoids. E: Spores are different reproductive structures. Common Pitfalls: Confusing somatic embryos with zygotic embryos; the presence of a protective gel does not create a true seed coat. Final Answer: Synthetic seeds

Question 4

Encapsulation matrices for producing synthetic seeds (e.g., sodium alginate–CaCl2 gels) are typically:

Accepted Answer

Introduction / Context: Encapsulation protects somatic embryos and allows handling similar to seeds. The physical chemistry of the gel determines water retention, gas exchange, and mechanical strength of synthetic seeds. Given Data / Assumptions: Common hydrogels include alginate crosslinked with calcium, carrageenan, and other polysaccharides. Gels must be stable in aqueous environments yet permeable to water and solutes. Somatic embryos are living and require moisture and oxygen. Concept / Approach: Calcium alginate forms a crosslinked polymer network that is insoluble in water but swells to form a hydrogel. This provides mechanical protection and a hydrated microenvironment while preventing the bead from dissolving during handling or sowing. Step-by-Step Solution: Identify the desired property: maintain bead integrity in moist media.Select material behavior: water-insoluble but water-swollen hydrogel.Therefore the correct description is “insoluble in water.” Verification / Alternative check: Standard encapsulation protocols drop alginate–embryo suspensions into CaCl2 baths to instantly form insoluble gel beads that are then rinsed and stored. Why Other Options Are Wrong: A: If soluble, beads would dissolve during sowing or culture. B/D/E: Not representative of hydrogel behavior required for synthetic seeds. Common Pitfalls: Confusing swelling with solubility; hydrogels can absorb water while remaining insoluble. Final Answer: Insoluble in water (hydrogel network that retains integrity)

Question 5

Somatic embryoids (from tissue culture) are best described as:

Accepted Answer

Introduction / Context: Somatic embryogenesis produces embryo-like structures from somatic cells without fertilization. Their morphology and developmental stages resemble zygotic embryos, making them valuable for clonal propagation and synthetic seed production. Given Data / Assumptions: Somatic embryos arise from single cells or small cell groups. They pass through globular, heart, torpedo stages akin to zygotic development. They do not naturally acquire a maternal seed coat. Concept / Approach: While organization parallels zygotic embryos, the absence of a seed coat is a defining difference. Encapsulation via hydrogels substitutes for protective layers during handling and sowing as synthetic seeds. Step-by-Step Solution: Match structural organization to embryos.Check for seed coat presence: somatic embryos lack it.Select the statement capturing both facts. Verification / Alternative check: Microscopic comparisons and regeneration protocols consistently show embryogenic polarity and organogenesis similar to zygotic counterparts. Why Other Options Are Wrong: B/D: Seed coats are absent; any coating is artificial. C: They are organized and embryo-like, not random masses. E: Unorganized callus is not equivalent to embryoids. Common Pitfalls: Confusing somatic embryos with shoot organogenesis or callus proliferation pathways. Final Answer: Identical to zygotic embryos in organization but lacking natural seed coats

Question 6

Encapsulating somatic embryos for synthetic seeds can be achieved by which method(s)?

Accepted Answer

Introduction / Context: Producing synthetic seeds at scale requires reproducible encapsulation. Two broad approaches are widely referenced: automated bead formation for throughput and chemical gelation for reliable capsule integrity. Given Data / Assumptions: Somatic embryos are sensitive to mechanical stress. Encapsulation must be uniform to ensure consistent germination. Hydrogel chemistry (e.g., alginate–Ca2+) underlies most bead formation. Concept / Approach: Automatic encapsulation devices dispense embryo–alginate droplets into CaCl2 baths, standardizing bead size. Gel complexation refers to the ionic crosslinking reaction that converts the droplet into a stable hydrogel bead. Combining process control with robust chemistry yields high-quality capsules. Step-by-Step Solution: Recognize the two complementary aspects: process engineering and gel chemistry.Automatic processes address scale and uniformity.Gel complexation provides the protective matrix.Therefore, select the option including both methods. Verification / Alternative check: Protocols in carrot, alfalfa, and woody species document both automated and manual gelation methods. Why Other Options Are Wrong: D: Protein coatings alone lack structural robustness. E: Dry pelleting without gel does not protect delicate embryoids adequately. Common Pitfalls: Overlooking embryo size distribution and dwell time in CaCl2, which affect bead strength and germination. Final Answer: Both (a) and (b)

Question 7

Species track record: the production of high-quality, uniform somatic embryos has historically been most successful in which crops?

Accepted Answer

Introduction / Context: Somatic embryogenesis success varies widely by species. Some model systems consistently yield uniform, vigorous embryos suitable for synthetic seed research and commercialization pilots. Given Data / Assumptions: Carrot and alfalfa have long-standing protocols with reliable embryogenesis. Uniformity and conversion rates are key for synthetic seed viability. Woody perennials and certain tropical species remain challenging. Concept / Approach: Species choice influences embryo morphology, synchronization, and germination. Carrot and alfalfa protocols deliver repeatable results, making them benchmark systems for encapsulation studies. Step-by-Step Solution: List species with robust literature support.Identify those with consistent embryo quality and uniformity.Select the combined option acknowledging both carrot and alfalfa. Verification / Alternative check: Numerous reports demonstrate high conversion rates from encapsulated embryos in these two species compared to more recalcitrant crops. Why Other Options Are Wrong: D/E: While research exists, uniformity and large-scale reliability are less established than in the model systems. Common Pitfalls: Assuming success in one species translates directly to another; medium composition and growth regulators must be optimized per crop. Final Answer: Both (a) and (b)

Question 8

Definition check: in plant tissue culture, “synthetic seeds” are best defined as:

Accepted Answer

Introduction / Context: The term “synthetic seed” can be confusing outside plant biotechnology. It specifically refers to encapsulated somatic embryos, not simply to any artificial or GM-derived seed product. Given Data / Assumptions: Somatic embryos arise through tissue culture techniques. Encapsulation matrices include alginate gels with additives (nutrients, growth regulators). The aim is seed-like handling and potential sowing without full in vitro steps. Concept / Approach: By embedding a viable embryo in a gel bead, one obtains a unit that mimics a seed functionally (protection, handling) even without a natural seed coat or endosperm. This is distinct from GM seed, which is a zygotic product bearing a transgene. Step-by-Step Solution: Define somatic embryo and encapsulation.Differentiate from GMO zygotic seeds and other propagules.Select the standard definition used in literature. Verification / Alternative check: Protocols universally describe synthetic seeds as encapsulated somatic embryos; the definition is consistent across species. Why Other Options Are Wrong: A: Lacks a living embryo. C: GM seeds are natural seeds with transgenes, not encapsulated embryoids. D/E: These are other propagules, not encapsulated somatic embryos. Common Pitfalls: Using “synthetic seed” as a catch-all term for any nontraditional propagule. Final Answer: Somatic embryos encapsulated in a suitable protective matrix

Synthetic Seeds Questions