Q.Correct the statement, if necessary, by changing the underlined word only: In tissue culture, amorphous mass of thin-walled parenchymatous cells developing from proliferating cells is called explant.
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🔒 Start your 14-day free trial to unlock the full solution →Concept understanding — Tissue Culture and Micropropagation
Tissue culture is a technology in which a whole plant is regenerated from an explant — any small piece of plant tissue — grown in vitro under sterile conditions in a nutrient medium containing sucrose, salts, vitamins, amino acids and growth regulators. This ability of a cell or explant to regenerate an entire plant is called totipotency, and using it to mass-produce genetically identical plants (somaclones) quickly is called micropropagation, now used commercially for crops like tomato, banana and apple. Because a plant's meristem stays free of virus even when the rest of the plant is infected, culturing meristem tissue allows scientists to recover virus-free plants of banana, sugarcane and potato. Tissu …
In plant tissue culture, the small piece of tissue used to start a culture and the mass of undifferentiated cells it later proliferates into are two different structures with two different names. …
The statement is incorrect as given; "explant" must be replaced with "callus", the unorganised proliferating cell mass produced during tissue culture.
In plant tissue culture (micropropagation):
- An explant is the small piece of living tissue (e.g., shoot tip, leaf disc, nodal segment) that is EXCISED from the parent plant and placed onto nutrient/culture medium to START the culture. It is the starting material, not the outcome of proliferation.
- Once placed on an appropriate nutrient medium (containing auxins and cytokinins), the explant's cells dedifferentiate and divide repeatedly to produce an unorganised, amorphous mass of thin-walled, relatively undifferentiated parenchymatous cells - this proliferated mass is called the callus. …
Showing the 12 most recent of 20 on this concept.
- CBSE 2026Set 57/1/11 markMCQQ.Pomato was produced by fusing protoplasts of (A) Tomato and Potato (B) Pomegranate and Tomato (C) Pomegranate and Potato (D) Pomegranate, Potato and Tomato
›Reveal solutionSolution
Pomato is a somatic hybrid plant created by fusing the protoplasts of a tomato plant and a potato plant.
The creation of 'Pomato' is a fascinating example of somatic hybridization, a powerful technique within plant biotechnology. This process involves the fusion of protoplasts from two different plant species or varieties, aiming to combine desirable traits that might not be achievable through conventional sexual reproduction. To understand Pomato, we first need to grasp what protoplasts are and how their fusion works.
A protoplast is essentially a plant cell from which the rigid cell wall has been enzymatically removed, leaving only the cell membrane enclosing the cytoplasm and nucleus. Without the cell wall, these naked cells become amenable to fusion. In somatic hybridization, protoplasts are isolated from two different parent plants, often using enzymes like cellulase and pectinase. These isolated protoplasts are then encouraged to fuse together, typically using chemical agents like polyethylene glycol (PEG) or through electrofusion. The resulting fused cell, containing genetic material from both parents, is called a somatic hybrid.
NoteSomatic hybridization is distinct from sexual hybridization. Sexual hybridization involves the fusion of gametes (pollen and ovule), while somatic hybridization involves the fusion of vegetative (somatic) cells' protoplasts. This allows for crosses between species that are sexually incompatible.
Once a somatic hybrid protoplast is formed, it is cultured in a suitable medium where it can regenerate a new cell wall, divide, and eventually develop into a callus. From this callus, a whole new plant, known as a somatic hybrid plant, can be regenerated using plant tissue culture techniques. The goal is to produce a hybrid plant that possesses a beneficial combination of characteristics from both parent plants. …
- CBSE 2025Set 57/6/11 markMCQQ.Assertion (A) : Isolated single cells can be fused to produce somatic hybrids. Reason (R) : Cells selected for somatic hybridisation have desirable characters.
›Reveal solutionSolution
Both statements are true, but the reason does not explain the assertion — fusion is a technical capability, while selection is about breeding goals.
The assertion speaks to a fundamental technique in plant biotechnology: protoplast fusion. When plant cells have their rigid cell walls enzymatically removed, they become protoplasts — naked cells bounded only by their plasma membranes. These isolated protoplasts can indeed be induced to fuse, typically using polyethylene glycol (PEG) or electrical pulses. The fusion merges the cytoplasm and nuclei of two different cells, creating a single hybrid cell that contains genetic material from both parents. This hybrid cell can then regenerate a cell wall, divide, and under the right culture conditions, develop into a complete plant — a somatic hybrid.
This process bypasses the sexual route entirely. Conventional breeding depends on compatible species that can cross-pollinate, but somatic hybridisation allows fusion between cells from species that would never mate in nature — even across genus boundaries. The technique has been used to combine traits from distantly related plants, creating novel combinations impossible through traditional methods.
Now the reason states that cells selected for this fusion carry desirable characters. This is absolutely true from a practical standpoint. Scientists do not randomly pick any two cells to fuse. They choose parent plants with specific valuable traits — disease resistance from one species, high yield from another, drought tolerance from a third. The selection is deliberate and goal-oriented, aimed at pooling beneficial characteristics into a single hybrid organism.
NoteThe NCERT textbook describes protoplast fusion as a method to create hybrids between otherwise incompatible species, emphasising that the technique overcomes natural reproductive barriers. …
- CBSE 2025Set ANNUAL1 markMCQQ.The method of producing thousands of plants through tissue culture is called:(a) Totipotency(b) Micropropagation(c) Somatic Hybridisation(d) None of the above
›Reveal solutionSolution
Micropropagation is the mass clonal propagation of plants from a small explant, grown on a sterile nutrient medium.
Tissue culture rests on the property of totipotency — the ability of a single somatic cell to regenerate into a whole plant — but totipotency is the underlying principle, not the propagation method itself, so option (a) is ruled out.
In micropropagation, a small piece of tissue (explant — e.g. a shoot tip or nodal segment) is surface-sterilised and placed on Murashige and Skoog (MS) medium containing sugar, minerals, vitamins, and plant growth regulators (auxins and cytokinins in a specific ratio). Under aseptic conditions, the explant proliferates into an undifferentiated mass called callus, or directly forms multiple shoots (organogenesis), which are then rooted and hardened before transfer to soil. Because all the regenerated plants (plantlets) arise from a single parent explant, they …
- CBSE 2024Set E1 markMCQQ.Capacity to generate a whole plant from a plant cell is called as(a) Tissue culture(b) Pluripotency(c) Totipotency(d) Micropropagation
›Reveal solutionSolution
Totipotency is the ability of a cell to generate a whole plant.
The capacity of a single (differentiated) plant cell to divide and develop into a complete plant is called totipotency. This property is the basis of plant tissue culture: an explant is grown on a suitable nutrient medium under sterile conditions, forms a mass of cells (callus), and is then induced to regenerate into a whole plan …
- CBSE 2024Set BOTANY1 markMCQQ.Fill in the blank selecting the appropriate alternative: The capacity of any cell or explant to generate a whole plant is called ____.(i) unipotency(ii) multipotency(iii) totipotency(iv) impotency
›Reveal solutionSolution
Totipotency is the capacity of any living plant cell to give rise to a whole new organism.
Totipotency is the ability of a single somatic cell or explant, given the appropriate nutrient medium (containing sugars, amino acids, and growth hormones), to dedifferentiate into a mass of unorganised cells (callus) and then redifferentiate into a complete new plant. This property, first demonstrated in plant tissue cul …
- CBSE 2023Set BOTANY1 markMCQQ.Fill in the blank selecting the appropriate term given under the bit: The capacity of a plant cell to give rise to a new plant is called _____.(a) totipotency(b) reproduction(c) budding(d) regeneration
›Reveal solutionSolution
Totipotency is the ability of a single (differentiated) plant cell to give rise to a whole new organism when provided suitable conditions.
The German botanist Gottlieb Haberlandt first proposed (1902) that plant cells possess an inherent capacity to regenerate a whole plant - a property he termed totipotency. This principle underlies modern plant tissue culture: a single somatic cell (explant) placed on a nutrient medium containing sugars, minerals, vitamins and plant growth regulators (auxins and cytokinins in the right ratio) can dedifferentiate to form an unorganized mass called callus, which then redifferentiates to regenerate a complete plantlet - a technique widely used for micropropagation, production of disease-free/virus-free plants, and somatic hybridiz …
- CBSE 2023Set ANNUAL1 markMCQQ.The pH of nutrient medium for plant tissue culture is in the range of _______.(a) 2 to 4.2(b) 5 to 5.8(c) 7 to 7.5(d) 8 to 9.5
›Reveal solutionSolution
Plant tissue culture nutrient media are generally maintained at a mildly acidic pH of about 5 to 5.8.
The nutrient (basal) medium used in plant tissue culture, such as MS (Murashige and Skoog) medium, is adjusted to a pH of roughly 5.0-5.8 before autoclaving. This mildly acidic range is optimal for nutrient and hormone uptake, for the solidifying action of agar, and for healthy callus …
- CBSE 2023Set ANNUAL1 markMCQQ.Somaclonal variation is obtained by which?(a) tissue culture(b) gamma rays(c) mixing of both(d) chemical mutation
›Reveal solutionSolution
Somaclonal variation arises from tissue culture.
Somaclonal variation refers to the genetic variation observed among plants (somaclones) regenerated from cultured somatic cells or tissues in vitro. It arises spontaneously during the culture process and can be exploited to select improved crop lines. It …
- CBSE 2022Set ANNUAL1 markQ.What is totipotency?
›Reveal solutionSolution
Totipotency is the ability of a single somatic cell to regenerate a whole new plant, and it is the biological basis of plant tissue culture technology.
Totipotency refers to the inherent capability of any living plant cell (given appropriate nutrient medium, growth regulators, and aseptic conditions) to divide and differentiate into an entire new plant. This property means that a single explant (a small excised piece of tissue) can, in principle, be used to regenerate a whole organism — this is precisely the biological principle that underlies plant tissue culture and micropropagation tech …
- CBSE 2022Set ANNUAL1 markMCQQ.The capacity to generate a whole plant from any cell/explant is called____(a) Totipotency(b) Biofortification(c) Somatic hybridization(d) Micropropagation
›Reveal solutionSolution
Totipotency is the capacity of any living plant cell to give rise to a complete organism.
Totipotency is the property, possessed by many plant cells, of being able to regenerate a whole new plant when grown in vitro (in culture) under appropriate nutrient and hormone conditions — this is the fundamental biological principle underlying plant tissue culture techniques. Biofortification is breeding crops with enhanced nutrition; somatic hybridization is fusion of protoplasts from two different somatic cells (usually of different species) to form a hybrid …
- CBSE 2021Set D1 markMCQQ.Which one of the following is possible in micropropagation ?(a) Asexual reproduction(b) Sexual reproduction(c) Both (A) and (B)(d) None of these
›Reveal solutionSolution
Micropropagation is asexual (vegetative) multiplication through tissue culture, producing genetically identical clones (somaclones).
Micropropagation is the technique of producing thousands of plants in vitro from small explants using tissue culture. Because the new plants develop from somatic (body) cells without the fusion of gametes, it is a form of asexual (vegetative) reproduction; the resulting plants are genetically i …
- CBSE 2021Set D1 markMCQQ.Every living cell of plant can give rise to the whole plant. This property is known as(a) Cloning(b) Somaclonal(c) Totipotency(d) All of these
›Reveal solutionSolution
The ability of a single cell to form a whole plant is totipotency.
Every living plant cell carries the complete genetic information of the organism. Given the right nutrient medium and hormones (auxin, cytokinin) in tissue culture, such a cell can dedifferentiate, divide and regenerate an entire plant. This inherent capacity is termed totipotency and is the basis of plant tissue culture and micropropagation. Cloning is the p …
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