Tissue Culture Questions in English

(B) The process of growing plant cells,tissues,or organs in a sterile,nutrient-rich medium under controlled laboratory conditions is known as $Plant \ tissue \ culture$. This technique is widely used for the micropropagation of plants,production of disease-free plants,and genetic improvement of crops. Therefore,the correct option is $B$.

(D) Tissue culture is a technique of growing plant cells,tissues,or organs in a sterile,controlled environment.
$1$. Maintaining a sterile environment is crucial to prevent contamination by microorganisms like bacteria and fungi.
$2$. Providing an optimal temperature (often around $24^oC$ to $28^oC$) is necessary for proper metabolic activity and growth.
$3$. $A$ suitable culture medium containing essential nutrients,vitamins,and plant growth regulators is required to support the growth of the explant.
Therefore,all these factors are essential for successful tissue culture.

(A) $Agar-Agar$ is a polysaccharide obtained from red algae (such as $Gelidium$ and $Gracilaria$).
It is widely used in laboratories as a solidifying agent to prepare culture media for the growth of microorganisms and plant tissue culture.
It provides a stable,jelly-like surface that supports the growth of cells or microbes while allowing nutrients to remain accessible.

(A) Callus culture is a technique in plant tissue culture where an unorganized mass of cells (callus) is grown on a nutrient medium.
$1$. Callus is typically sterilized using chemical agents like sodium hypochlorite or ethanol,not $UV$ light,as $UV$ light can damage the genetic material of the cells.
$2$. The standard temperature for callus culture is generally maintained between $22^oC$ to $28^oC$,so $24^oC$ is an acceptable range.
$3$. Auxins and cytokinins are essential plant growth regulators used to induce cell division and differentiation in callus culture.
$4$. Callus is essentially an unorganized mass of cells formed by continuous cell division.
Therefore,the statement that callus is sterilized using $UV$ light is incorrect.

(C) The suspension culture method involves growing plant cells or small cell aggregates in a liquid medium. $A$ rotary shaker is essential in this method to provide continuous agitation,which ensures proper aeration,uniform distribution of nutrients,and prevents the cells from clumping together. Therefore,the correct answer is the suspension culture method.

(A) Callus and suspension cultures are widely used in plant biotechnology for various purposes.
$1$. Production of biomass: These cultures are used to produce secondary metabolites and biomass on a large scale.
$2$. Isolation of protoplasts: Callus tissue is a common source for isolating protoplasts for somatic hybridization.
$3$. Production of transgenic plants: These cultures are used as targets for genetic transformation to create transgenic plants.
$4$. Obtaining embryos from dormant seeds is a process related to seed germination physiology and is not an application of callus or suspension culture techniques.

(C) Interspecific hybridization often results in the formation of non-viable seeds or embryos due to post-fertilization barriers or endosperm failure.
To overcome this,the immature or hybrid embryo is excised from the developing seed and grown on a nutrient medium under sterile conditions.
This technique is known as embryo culture,which allows the successful development of hybrid plants that would otherwise fail to germinate.

(B) new species is typically formed through evolutionary processes like natural selection,genetic drift,and reproductive isolation.
$A$. Tissue culture is a technique for plant propagation.
$B$. Cloning produces genetically identical copies of an organism,not a new species.
$C$. Hybridization involves crossing two different varieties or species to produce offspring with combined traits.
$D$. Mutation is a primary source of genetic variation that drives evolution and the formation of new species.
Therefore,cloning is the process that does not contribute to the formation of a new species in the evolutionary sense.

(D) Botanical gardens serve as ex-situ conservation centers and research facilities.
To develop new plant species or propagate rare and endangered varieties,various biotechnological and horticultural techniques are employed.
$A$. Grafting is a traditional horticultural technique used to combine the desirable traits of two different plants.
$B$. Tissue culture is a modern technique used for micropropagation and the development of disease-free plantlets.
$C$. Cloning is used to produce genetically identical copies of plants.
Since all these methods are utilized in botanical research and conservation,the correct answer is $D$.

(C) $Conservatory$ is a specialized structure,often made of glass,designed to provide a controlled environment for the cultivation and protection of rare or exotic plants. Unlike a standard greenhouse,which is primarily used for commercial plant production,a conservatory is specifically maintained to house and preserve rare plant species that require specific environmental conditions to survive.

(D) Botanical gardens serve as ex-situ conservation centers and research facilities. To develop new plant species or varieties,various biotechnological and horticultural techniques are employed.
$1$. Grafting is a traditional method used to combine desirable traits from two different plants.
$2$. Tissue culture allows for the rapid propagation of plants and the creation of genetically uniform clones or new variants under controlled conditions.
$3$. Cloning is a technique used to produce genetically identical copies of an organism.
Since all these methods are utilized in botanical research and plant breeding,the correct answer is $D$.

(D) $Micropropagation$ is a modern technique used to obtain a large number of plantlets through plant tissue culture.
It is termed $micropropagation$ due to the very small size of the propagules used.
This process involves the repeated subculturing of an explant by modifying the culture medium to induce the formation of numerous plantlets from a single explant.
$Somatic$ $embryogenesis$,which refers to the development of embryos from somatic cells,is a key technique utilized within $micropropagation$.

(D) The correct answer is $D$.
Somatic hybridization is a technique used to produce somatic hybrids by fusing protoplasts from two different plant varieties or species.
To achieve this,the cell walls of the plant cells are first removed using enzymes.
The resulting protoplasts are then brought into contact and induced to fuse using specific agents known as fusogens.
Commonly used chemical fusogens include Polyethylene glycol $(PEG)$ and sodium nitrate $(NaNO_3)$.
Electrofusion is another physical method used for this purpose.
Once fused,the protoplasts regenerate their cell walls and develop into somatic hybrid cells.

(A) : Clonal propagation can be characterized by $PCR$ and $RAPD$.
The polymerase chain reaction $(PCR)$ technique generates microgram $(\mu g)$ quantities of $DNA$ copies (up to billion copies) of the desired $DNA$ (or $RNA$) segment, present even as a single copy in the initial preparation, in a matter of a few hours.
$RAPD$ stands for Random Amplification of Polymorphic $DNA$.
It is a type of $PCR$, but the segments of $DNA$ that are amplified are random.
No knowledge of the $DNA$ sequence for the targeted gene is required, as the primers will bind somewhere in the sequence, but it is not certain exactly where.
Its resolving power is much lower than targeted, species-specific $DNA$ comparison methods, such as short tandem repeats.

(C) : Meristem is a localized group of cells,which are actively dividing and undifferentiated but ultimately give rise to permanent tissue.
Even if the plant is infected with a virus,the meristematic tissue remains free of the virus.
Therefore,the meristem can be removed and grown in vitro to obtain virus-free plants.
Cultivation of axillary or apical shoot meristems is called meristem culture.
Both apical and axillary meristems are generally free from viruses.

(A) : Plant tissue culture,also called micropropagation,is the growth of plant cells outside the plant body in a suitable culture medium which contains a mixture of nutrients in solid or liquid form,under controlled environmental conditions.
Tissue culture technique is based on the totipotent nature of plant cells or the phenomenon of totipotency,$i.e.$,each and every plant cell has the inherent capacity to develop into a complete plant.
The entirely vegetatively produced descendants of somatic cells are collectively called a clone.
They are genetically identical to the parents,thus ensuring the production of a genetically uniform population.

(B) is the correct answer. Somatic embryos develop from somatic cells,not from microspores. Their development is comparable to that of a zygotic embryo. They are similar to a normal embryo except that their development is induced from a diploid somatic cell. Somatic embryo culture is typically induced by a high concentration of an auxin,such as $2, 4-D$. Microspores are haploid cells that give rise to pollen grains,not somatic embryos.

(C) : Meristem is a localized group of cells that are actively dividing and undifferentiated, ultimately giving rise to permanent tissue.
Even if a plant is infected with a virus, the meristem remains free of the virus.
Therefore, the meristem can be removed and grown $in vitro$ to obtain virus-free plants.
The cultivation of axillary or apical shoot meristems is known as meristem culture.
The apical or axillary meristems are generally free from viruses.

(D) : Genetic variation present among plant cells during tissue culture is called somaclonal variation.
The term somaclonal variation is also used for the genetic variation present in plants regenerated from a single culture.
This variation has been used to develop several useful varieties.

(A) The correct answer is $A$.
Meristem is a localized group of cells that are actively dividing and undifferentiated, eventually giving rise to permanent tissues.
Even if a plant is infected with a virus, the meristematic tissue remains free of the virus.
Therefore, the meristem can be excised and grown $in vitro$ to obtain virus-free plants.
Cultivation of axillary or apical shoot meristems is known as meristem culture, which is the standard technique for producing virus-free plants.

(D) The capacity to generate a whole plant from any cell or explant is known as $Totipotency$.
This is a fundamental principle of plant tissue culture.
$Biofortification$ refers to breeding crops with higher levels of vitamins and minerals.
$Aquaculture$ is the farming of aquatic organisms.
$Germ \text{ } plasm$ refers to the collection of seeds or plants having diverse alleles of all the genes in a given crop.

(C) Plant tissue culture medium typically contains essential nutrients such as carbon sources (e.g.,sucrose),inorganic salts,vitamins,amino acids,and plant growth regulators (like auxins and cytokinins).
$FSH$ (Follicle Stimulating Hormone) is a gonadotropic hormone found in animals,which regulates reproductive processes.
It is not a component of plant culture media,as plants do not possess the endocrine system found in animals.

(B) In plant tissue culture,any part of a plant (such as a leaf,stem,root,or meristematic tissue) that is excised and placed in a sterile nutrient medium to initiate a culture is known as an $Explant$.
$Micropropagation$ refers to the process of producing large numbers of progeny plants through tissue culture.
$Transplant$ refers to moving a plant from one location to another.
$Plsciculture$ is not a standard biological term related to plant tissue culture.

(D) Tissue culture is a technique of growing plant cells,tissues,or organs in a sterile,controlled environment on a nutrient medium.
The nutrient medium (often called Murashige and Skoog medium or $MS$ medium) must provide all the essential components for the growth and development of the explant.
$I.$ Sucrose acts as a carbon and energy source.
$II.$ Inorganic salts provide essential macro and micronutrients (minerals) required for plant metabolism.
$III.$ Amino acids serve as a nitrogen source for protein synthesis.
$IV.$ Vitamins (such as thiamine,nicotinic acid,and pyridoxine) are essential co-factors for enzymatic reactions.
Therefore,all these components are necessary for the successful growth of plant tissue in vitro.

(D) The process of producing virus-free plants is known as meristem culture.
Even if a plant is infected with a virus,the apical and axillary meristems remain free of the virus.
This is because the meristematic cells divide at a rate faster than the virus can replicate and spread through the tissue.
Therefore,the meristem is excised and grown in vitro to obtain a healthy,virus-free plant.

(B) $Pomato$ is a somatic hybrid produced by the fusion of protoplasts of tomato ($Solanum$ $lycopersicum$) and potato ($Solanum$ $tuberosum$).
It is created through somatic hybridization,a technique in plant tissue culture.
While it is a hybrid plant,it does not possess all the desired combinations of characters (e.g.,it did not produce both high-quality tomatoes and potatoes in a single plant as expected).
Therefore,option $B$ is the most accurate description among the choices provided,as $C$ incorrectly mentions guava.

(C) Micro-propagation is a tissue culture technique used to produce a large number of plants in a very short duration.
This method involves the propagation of plants from explants (small pieces of plant tissue) under sterile conditions in a laboratory.
Because the plants produced are genetically identical to the original plant,they are referred to as somaclones.
This technique is widely used in agriculture and horticulture for the rapid multiplication of high-quality,disease-free plants.

(B) Coconut milk is widely used in plant tissue culture media because it is a rich natural source of $Cytokinin$ (specifically $Zeatin$).
$Cytokinins$ are plant hormones that promote cell division (cytokinesis) and help in the growth and differentiation of plant tissues in vitro.
Therefore,the presence of $Cytokinin$ makes coconut milk an essential supplement for successful tissue culture.

(C) Haploid plants can be produced through tissue culture techniques using pollen grains (microspores).
Since pollen grains are haploid $(n)$ cells formed by meiosis,culturing them on a suitable nutrient medium allows them to develop into haploid embryos and subsequently into haploid plants.
This technique is widely used in plant breeding to obtain homozygous lines rapidly.

(C) The meristem (apical and axillary) is free from viruses even in infected plants because the virus does not spread into the meristematic tissue due to the high rate of cell division and the lack of vascular connection. Therefore,meristem culture is the most effective technique to produce virus-free plants from infected stock.

(D) Somaclones are genetically identical plants produced from a single explant through the process of plant tissue culture (micropropagation). Since they are derived from somatic cells without sexual reproduction,they maintain the same genetic makeup as the parent plant.

(A) In tissue culture,the $Apical$ $meristem$ is used to obtain virus-free or disease-free plants. This is because the $Apical$ $meristem$ is the region of active cell division and is generally free from viral infections even if the rest of the plant is infected. By culturing this meristem,a healthy,disease-free plant can be regenerated.

(A) Tissue culture, specifically micropropagation, involves the production of genetically identical plants (clones) in an $in vitro$ environment.
To verify the genetic uniformity of these clones, molecular markers are used.
$PCR$ (Polymerase Chain Reaction) and $RAPD$ (Random Amplified Polymorphic $DNA$) are standard molecular techniques used to assess genetic stability and ensure that the tissue-cultured plants are true-to-type clones.

(C) Before transferring the explant onto the culture medium,it must be disinfected through surface sterilization. This process typically involves the use of chemical agents such as clorax water,sodium hypochlorite,calcium hypochlorite,or methiolate. Extreme care is required during this procedure to ensure that the explant cells remain viable and do not die due to the chemical treatment.

(A) The concept of totipotency states that any living plant cell has the inherent capacity to generate a whole new plant.
In plant tissue culture,somatic embryos can be induced from various plant cells because of this property of totipotency.
Since any viable plant cell possesses the potential to differentiate into somatic embryos under appropriate culture conditions,the Reason correctly explains the Assertion.
Therefore,both the Assertion and Reason are correct,and the Reason is the correct explanation of the Assertion.

(A) The concept of $Totipotency$ states that any living plant cell has the genetic potential to differentiate and develop into a whole plant or somatic embryo under appropriate culture conditions. Somatic embryos are non-zygotic embryo-like structures that can be induced from various types of plant tissues in vitro. Since the ability to form somatic embryos is a direct consequence of the $Totipotency$ of plant cells,the Reason correctly explains the Assertion.

(A) Somatic hybridization is a significant technique in plant tissue culture that involves the fusion of protoplasts from two different plant varieties.
Protoplasts are plant cells whose cell walls have been enzymatically removed,leaving them 'naked'.
When these naked protoplasts from two different plants are fused,they form a somatic hybrid.
This process allows for the combination of desirable traits from two different species or varieties that might not be crossable through traditional sexual reproduction.
Therefore,protoplast fusion is indeed a major advantage and application of tissue culture technology,and the reason provided correctly explains the process of forming such a hybrid.

(N/A) Apical and axillary meristems of plants are best suited for making virus-free plants.
In a diseased plant,these meristematic regions remain free from viral infection even if the rest of the plant is infected.
This is because the rate of cell division in the meristem is very high,which prevents the virus from establishing itself in these tissues.
Scientists remove the apical or axillary meristems of the infected plant and grow them in vitro (tissue culture) to obtain healthy,virus-free plants.
This technique has been successfully used to produce virus-free plants of banana,sugarcane,and potato.

(B) Micropropagation is a method of producing new plants in a short duration using plant tissue culture.
Some major advantages of micropropagation are as follows:
$1$. Micropropagation helps in the propagation of a large number of plants in a short span of time.
$2$. The plants produced are genetically identical to the mother plant,known as somaclones.
$3$. It leads to the production of healthier plantlets,which often exhibit better disease-resisting powers compared to traditional methods.

(N/A) The major components of the culture medium used for the in vitro propagation of explants include:
$1$. Carbon sources: Primarily sucrose,which serves as an energy source.
$2$. Inorganic salts: Essential minerals required for plant growth.
$3$. Vitamins: Necessary for metabolic processes.
$4$. Amino acids: Sources of nitrogen for protein synthesis.
$5$. Water: The solvent for all nutrients.
$6$. Agar-agar: $A$ solidifying agent used to provide a firm support for the explants.
$7$. Growth hormones: Specific plant growth regulators such as auxins and cytokinins (or gibberellins) are added to induce differentiation and growth.

(A) As traditional breeding techniques failed to keep pace with demand and to provide sufficiently fast and efficient systems for crop improvement,a technology called tissue culture was developed.
Scientists learned during the $1950s$ that a whole plant could be regenerated from explants,which is any part of a plant taken out and grown in a test tube under sterile conditions in special nutrient media.
This capacity to generate a whole plant from any cell/explant is called totipotency.
The nutrient medium must provide a carbon source such as sucrose,inorganic salts,vitamins,amino acids,and growth regulators like auxins and cytokinins.
By applying these methods,it is possible to achieve the propagation of a large number of plants in very short durations. This method of producing thousands of plants is called micropropagation.
Each of these plants will be genetically identical to the original plant,known as somaclones. Many important food plants like tomato,banana,and apple have been produced on a commercial scale using this method.
Another important application is the recovery of healthy plants from diseased ones. Even if a plant is infected with a virus,the meristem remains free of the virus. Hence,one can remove the meristem and grow it in vitro to obtain virus-free plants.
Scientists have also isolated single cells and,after digesting their cell walls,obtained naked protoplasts. Protoplasts from two different varieties can be fused to form hybrid protoplasts,which can be grown into new plants called somatic hybrids. This process is known as somatic hybridization.

(N/A) The process described is somatic hybridization,which involves the fusion of protoplasts from two different plant species.
$(1)$ Cellulase and pectinase are enzymes used to digest the cell wall to isolate protoplasts.
$(2)$ The process of fusing these protoplasts is called Somatic hybridization.
$(3)$ The resulting plant obtained from the fusion of tomato and potato protoplasts is known as Pomato.
$(4)$ The term used to denote such plants is Somatic hybrid.

(B) Plants obtained by protoplast culture are called somatic hybrids because they are produced by the fusion of protoplasts derived from somatic cells of two different plant varieties or species. This process involves the removal of cell walls,followed by the fusion of the remaining protoplasts,which is a non-sexual method of hybridization.

(N/A) $\Rightarrow$ The process of fusing protoplasts obtained from two different varieties of plants,each having a desirable character,to form a hybrid protoplast is known as protoplast fusion. This technique is used in plant tissue culture to create somatic hybrids.

(N/A) No,it is not wrong to call them 'clones'.
Micropropagation is a method of asexual reproduction (tissue culture) where plants are produced from a single parent cell or tissue.
Since the process involves mitosis and does not involve meiosis or fertilization,there is no genetic recombination.
Therefore,every plant produced through this technique is genetically identical to the parent plant and to each other.
Such genetically identical individuals are referred to as 'clones' or 'somaclones'.

(B) hybrid is typically produced through sexual hybridization,which involves the fusion of gametes from two different plant varieties.
In contrast,a somatic hybrid is produced by the fusion of isolated protoplasts from two different varieties of plants.
These fused protoplasts are then cultured to regenerate a new hybrid plant,a process known as somatic hybridization.

(B) Plant cells possess meristematic tissues that retain the capacity for continuous cell division,which is essential for growth and regeneration in tissue culture.
In contrast,most animal cells are highly differentiated and have lost the capacity for indefinite division,making them more difficult to culture in vitro.
Therefore,the presence of totipotent or meristematic cells makes plant tissue culture more feasible.

(N/A) The culture medium,also known as the nutrient medium,acts as a 'highly enriched laboratory soil' because it provides all the essential components required for the growth and development of plant cells or tissues in vitro.
It contains a carbon source (typically $Sucrose$),inorganic salts,essential vitamins,amino acids,and specific growth regulators such as $Auxins$ and $Cytokinins$.
Just as natural soil provides nutrients to plants in the field,the culture medium provides a controlled,optimized,and nutrient-dense environment that supports rapid cell division and differentiation in a laboratory setting.