RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture

Rajasthan Board RBSE Class 12 Biology Chapter 16 Plant Tissue Culture

RBSE Class 12 Biology Chapter 16 Multiple Choice Questions

Question 1.
Who is the credited for producing haploid plants from anther lobe culture?
(a) Johari and Maheshwari
(b) Haberlandt
(c) P.R. White
(d) Guha and Maheshwari
Answer:
(d) Guha and Maheshwari

RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture

Question 2.
Disease-free plants are obtained from virus-infected plant by?
(a) Embryo culture
(b) Root culture
(c) Pollen culture
(d) Apical meristematic culture
Answer:
(d) Apical meristematic culture

Question 3.
Who is known as the father of Plant Tissue culture?
(a) Robert Hooke
(b) Haberlandt
(c) Steward
(d) Cocking
Answer:
(b) Haberlandt

Question 4.
Ti plasmid is found in?
(a) A.tumefaciens
(b) A. rhi-bogenes
(c) E.coli
(d) Bacillus thermogenesis
Answer:
(a) A.tumefaciens

Question 5.
Who is credited for obtaining Protoplast by enzymatic degradation of Plant cell wall?
(a) T. Murashige
(b) E.Ball
(c) F.W. Went
(d) E.C. Cocking
Answer:
(d) E.C. Cocking

RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture

Question 6.
For triploid culture in plants, which is taken as explant?
(a) Apical Meristematic tip
(b) Embryo
(c) Endosperm
(d) Anther lobe/Pollensa
Answer:
(c) Endosperm

Question 7.
Indirect gene transfer is done in plants by?
(a) Gene gun
(b) Electroporation
(c) Microinjection
(d) Agrobacterium
Answer:
(d) Agrobacterium

Question 8.
Insect-resistant Bt gene is found in which of the following?
(a) Bacillus subtilis
(b) Bacillus thermogenesis
(c) Bacillus anthracis
(d) Pseudomonas citrus
Answer:
(b) Bacillus thermogenesis

RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture

Question 9.
For which characteristic, a gene was transferred in “Golden rice”?
(a) Vitamin A
(b) Vitamin C
(c) Vitamin D
(d) Vitamin B
Answer:
(a) Vitamin A

Question 10.
A special feature of “Flavr-Savr” tomatoes is?
(a) Drought resistant
(b) High salinity resistant
(c) Strong fruit wall
(d) All of the above
Answer:
(c) Strong fruit wall

Question 11.
Bt gene containing cotton is called?
(a) Aseptic cotton
(b) Romil cotton
(c) Golden cotton
(d) Killer cotton
Answer:
(d) Killer cotton

RBSE Class 12 Biology Chapter 16 Very Short Answer Questions

Question 1.
Define totipotency.
Answer:
The capacity or potential of a plant cell to regenerate the whole plant of which it is a part of is called · totipotency. Due to this property, the whole plant can be regenerated through tissue culture technique.

Question 2.
What is an artificial seed?
Answer:
The encapsulated somatic embryo is called artificial seed. The somatic embryo is protected by covering it with calcium alginate beads or by desiccating it. Thus artificial seeds are produced from somatic embryos.

RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture

Question 3.
What is callus?
Answer:
The unorganised mass of cells developed from the cultured meristematic cells is called callus. The cells in the callus are generally parenchymatous in nature.

Question 4.
What is the importance of haploid plant production?
Answer:

  • Haploid plant production through anther and pollen culture as well as the ovary or ovum culture is of immense use in plant breeding programme carried out for improvement of crops.
  • It enables raising plants which express recessive traits.
  • It is helpful in producing genetically homozygous plants which serve as parents in crossbreeding.
  • Homozygous plants can be raised by diploidization of haploids through colchicine treatment.

Question 5.
What are the different types of nutrient media used in tissue culture?
Answer:

  • The culture media developed by White’s (1953); Gamborg et. al. (1968) and M.S. medium (1962).
  • Of these. M.S. medium (Murashige and Skoog medium) is commonly used for general experiments of plant tissue culture.

Question 6.
What do you understand by micropropagation?
Answer:
The modern technique of rapid multiplication of plants through tissue culture is called micropropagation. This technique has been used for multiplication of novel plants at commercial level. By this technique, a large population of similar plants can be raised in a small space in a relatively short time.

RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture

Question 7.
Write the names of any three methods of direct gene transfer.
Answer:

  • Gene gun method
  • Electroporation
  • Lipofection
  • Microinjection

Question 8.
What do you understand by indirect gene transfer?
Answer:
When gene transfer is done through some biological vector, the process is called the indirect method. In this process, the desired gene is first transferred in the vector and than through the vector, it is transferred into the target plant. Hence such a transfer of gene is called indirect gene transfer.

Question 9.
What are the different components of artificial seed?
Answer:
The artificial seed contains, the embryo and shoot bud, nutrients, plant hormones, pesticide and antibiotic substances.

Question 10.
Define the following:

  1. Culture medium
  2. Protoplast
  3. Explant
  4. Transgenic plant

Answer:
1. Culture medium:
The nutrient medium, the chemical composition of which is precisely known and which is used to raise tissue culture and its multiplication is known as culture medium.

2. Protoplast:
The contents of the plant cell devoid by the cell wall collectively constitute the protoplast. Protoplast is thus a plant cell without a cell wall.

3. Explant:
The part of the plant used for raising tissue-culture is known as explant. Meristematic tissue, part of root, stem or leaves and flower and floral parts can be used as explant.

4. Transgenic plant:
Genetically modified plants are known as transgenic plants. Transgenic plants are developed by introducing desired features through recombinant DNA technique through genetic engineering

RBSE Class 12 Biology Chapter 16 Short Answer Questions

Question 1.
Explain microinjection technique of gene transfer.
Answer:
Microinjection:
In this method, genes are injected in plant protoplasts or cells with the help of glass needle of 0.5 – 1.0 mm diameter or micropipette directly in the cytoplasm or nucleus of the protoplasts or cells of plants. This is the suitable method of transferring genes in the isolated protoplasts.
RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture img 1

Question 2.
Write a note on any two insect-resistant plants.
Answer:
Several important crop plants are attacked by a variety of insects and pests. Bacillus thermogenesis bacterium is known as Bt in short. It was discovered that this was instrumental in causing the death of larvae of four species of Bollworm. This bacterium was registered as a biopesticide in the U.S.A. in 1961. A gene called a cry gene is found in this bacterium. This gene (cry gene) codes for a protein which kills the insect pests. This gene was separated from Bt bacterium and was incorporated in the genome of the cotton plant. The cotton variety so developed is called Bt cotton or killer cotton. This cotton is resistant to the Bollworm.

RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture

Question 3.
Write a note on the steps of tissue culture.
Answer:
1. Selection of explant and pretreatment:
Selection of explant depends on objective and experimental requirements. For callus culture, and healthy, part of the plant can be used as explant. The explant is washed under running water with the help of chemical Tween-20. This treatment cleans dust and microbes present on the surface.

2. Surface Sterilization of explant:
The selected explants are surface sterilized by appropriate disinfectant chemical under laminar airflow. This results in to complete sterilization of explant. Depending upon the nature of explant various types of disinfectants such as Mercuric chloride (Hg Cl2), Ethanol, Silver nitrate (AgNO3), Bromine or Chlorine water can be used.

3. Initiation of Culture:
The surface-sterilized explant is transferred on a suitable nutrient medium under aseptic conditions and transferred to the culture room. In a culture chamber, callus formation is initiated in due course of time. The explant and callus may be transferred to fresh medium for multiplication.

Question 4.
Differentiate between a normal embryo and somatic embryo?
Answer:
Culture of a mature or immature embryo of plants is called embryo culture. Embryo culture is used to induce germination of the mature embryo and for development of an immature embryo. When an embryo develops from somatic cells, it is called the somatic embryo.

It can be haploid or diploid depending upon the somatic cells from which it develops. The normal embryo is formed from the zygote. This is diploid and is formed by the fusion of male and female gametes.

RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture

Question 5.
Describe the method of micropropagation and its significance.
Answer:
The regeneration of plants through tissue culture technique is called micropropagation. In this technique, plantlets are developed through differentiation in the callus and these plantlets are transferred to nature after hardening and acclimatization.

This technique has been adopted to regenerate commercially important plants such as many species of orchids (Cattleya, Cymbidium, Dendrobium, Vanda) and many ornamental plants such as “Gerbera”, Carnation, Bignonia, Chrysanthemum, etc. Many institutions and universities are engaged in a multiplication of important forestry and horticultural plants by micropropagation.

Question 6.
What is embryo rescue technique? Write its importance.
Answer:
It is very difficult to produce hybrids in case of interspecific and inter-generic crosses (crosses between distantly related plants), because abnormal development of the endosperm causes the premature death of the hybrid embryo and leads to sterile seeds. The embryo from such sterile hybrid seeds can be excised at an appropriate time and cultured on a suitable nutrient medium to produce novel hybrids which are otherwise not possible. This is known as Embryo Rescue. Several useful hybrids were produced in a variety of crops using this technique.

Question 7.
Comment on Ti plasmid.
Answer:
Among the various vectors used in plant transformation, the Ti-plasmid of Agrobacterium tumefaciens has been used extensively. This bacterium contains large-sized plasmid, known as Ti-plasmid (tumour-inducing plasmid) and a portion of this plasmid referred to as T-DNA (transferred DNA).

When is transferred to plant genome, in the infected cells it causes these plant tumours (crown galls). This means that A. tumefacient has natural ability to transfer T-DNA of its plasmid into the plant genome (plant chromosomes) upon infection of cells at the wounded site and therefore this bacterium is known as ‘natural genetic engineer of plants’. Ti-plasmid can be used as a vector for inserting useful foreign genes into a genome of plant cells.

RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture

Question 8.
What do you understand by tissue culture?
Answer:
Culture of plant protoplast, cell, tissue, organ or complete system on chemically known medium under aseptic condition is known as tissue culture. Plant tissue culture is the modern technique through which regeneration of commercially important plants can be carried out on commercial level in a small space in a relatively short period and conveniently. It is a main tool of biotechnology and is extensively used in developing genetically modified plants or transgenic plants.

RBSE Class 12 Biology Chapter 16 Essay Type Questions

Question 1.
Write a brief note on the history of tissue culture.
Answer:
Plant tissue culture was first of all successfully conducted by Haberland (1902). This was the beginning of the culture of a plant cell under aseptic condition. Extensive work was carried out by various scientist in this field and presently it is widely used for regeneration of commercially useful Novel plants and also for developing transgenic plants.
Modern Cell theory:

  • A cell is a structural, functional and fundamental unit of life.
  • New cells arise from pre-existing cells.
  • All types of metabolic reactions take place in the cell.
  • Genetic information is transferred from one generation to next through cells.

According to cell theory, each and every cell of any plant posses all characteristics through which the whole plant can be regenerated. The capacity of producing complete plant from any cell is called “Totipotency”. The term totipotency was first of all used by Morgan (1909).

Due to this totipotency property, the whole plant can be regenerated from a plant cell. This was experimentally proved by Haberlandt (1902). Most of the animals lack the property of totipotency. Culture of plant protoplast, cell, tissue, organ or complete system on chemically known medium under sterile and controlled conditions is called Tissue culture.

Plant tissue culture was first of all conducted by a German scientist, Gottlieb Haberlandt (1902). Contribution of various scientists in the field of plant tissue culture has been shown in Table.
RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture img 2

RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture

Question 2.
What are Transgenic plants? How these are developed? Write their importance.
Answer:
Genetically Modified Plants Or Transgenic Plants:
Transgenic plants are genetically engineered plants. These are developed by introducing new qualities through recombinant DNA technique during plant breeding programme. These new qualities pass in the progeny generation after generation.

These genetically engineered plants or organisms are called genetically modified organisms (GMO). The products obtained from such plants are referred to as genetically modified food (GM food).

During the last few decades many transgenic plants both among dicotyledons and monocotyledons, have been developed through genetic engineering and these are being tested in the crop fields.
Transgenic plants of desired species can be developed by the following steps:

  • Identification and isolation of the gene of desired features.
  • Formation of recombinant plasmid and transformation of Agrobacterium.
  • Transfer of transformed Agrobacterium in the cells of the target plant.
  • Selection of transformed plant cells, their culture and regeneration.
  • Expression of the desired gene in the developed transgenic plants.

Importance of Transgenic plants:
As Bioreactors:
Genetically modified plants are used as bioreactors. We know plants are like chemical factories and are capable of synthesizing several types of chemical compounds by using sunlight as the source of energy.

By incorporating right (desired) genes plants can be made to serve as bioreactors to produce the desired type of compounds such as amino acids, proteins, vitamins, pharmaceutical products, enzymes etc. for use in food and medicine industry.

Thus transgenic plants are being used to produce various types of chemicals. Because of this, the field of biotechnology is called molecular farming.

Some of the plants developed for molecular farming are:

  • “Golden Rice” (Vitamin A enriched).
  • Super Potato.
  • Improved seed protein quality.
  • Edible vaccines.
  • Important medicines.
  • Biodegradable Plastic.
  • Genetically engineered metabolism.

RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture

Question 3.
Describe vector-mediated methods of gene transfer in plants.
Answer:
Transfer of desired genes and expression of these genes into plant cells is a modern application of plant tissue culture. In vector-mediated gene transfer, some biological agent is employed for transferring desirable genes into the plant cell. This vector-mediated transfer is also known as indirect gene transfer.
(1) Vector Mediated or indirect Gene Transfer:
In this procedure, the DNA is transferred with the help of some vector. There are three methods of this –
1. Agrobacterium-mediated Gene Transfer:
Among the various vectors used in plant transformation, the Ti-plasmid of Agrobacterium tumefaciens has been used extensively. This bacterium contains large-sized plasmid, known as Ti-plasmid (tumour-inducing plasmid) and the portion of this plasmid referred as T-DNA (transferred DNA) when is transferred to plant genome, in the infected cells, it causes plant tumours (crown galls).

This means that A. thermogenesis has natural ability to transfer T-DNA of its plasmid into plant genome at the site of infection, and therefore this bacterium is known as “natural genetic engineer of plants”. Because of this unique property. Ti-plasmid can be used as vectors for inserting useful foreign genes into plant cells and tissues.

The foreign genes (transgenes), i.e., the gene of interest(e.g. Bt gene for insect resistance) and plant selection marker gene, usually an antibiotic gene like no-till which confer resistance to kanamycin are cloned in place of the T-DNA region of Ti plasmid.

There is a possibility of tumour formation in plants by Ti plasmid. Hence for developing transgenic plants the tumour inducing gene (T-DNA) is separated from the plasmid DNA of Agrobacterium and in place of this desired gene is incorporated. Now the desired gene containing Agrobacterium is cultured with the tissues of the plant in which the desired gene is to be transferred.

Normally the rings or discs of leaves of tomato, tobacco, Petunia, rose etc. are used for composite culture because the acetosyringone produced by the rings or discs of leaves activate the operons of Ti plasmid. As a result of activation of these operons the desired gene containing Ti plasmid enters in several cells and gets incorporated in the genome of the plant cells. After 2 to 3 days of composite culture, the transformed cells are cultured in a suitable medium. This technique can be used for dicotyledon plants only.

Up to the beginning of 20th century Agrobacterium tumefaciens and associated species were considered as causative of plant diseases. But after knowing its ability to transfer foreign DNA, it is now used in Genetic engineering and due to extensive use in genetic engineering, it is known as Natural Genetic engineer.

Transformation of the gene in plants can be detected on the basis of production of amino acids by the genes present in the plasmid of this bacterium. The genetically transformed cells produce opines. These opines are of different types which depend on the strain of the Agrobacterium. The strains of A. thermogenesis produce octopine and nopaline whereas strains of A. rhizogens produce atropine and man opine opines.

In various research institutes, scientists are using Ti plasmid as a vector. By inserting desired and important genes in T DNA we can produce many important characteristics in plants such as Herbicide tolerance, Pathogen tolerance, Stress tolerance, increase in nutritive value (enrichment of rice with vitamin A, golden rice), improvement in nitrogen fixation.

Agrobacterium does not infect monocot plants normally but in 1994, Japanese scientists were able to do transformation with the help of Ti plasmid in rice.

2. Virus Mediated Gene Transfer:
Both DNA and RNA viruses act as an ideal vector for transfer of desired genes. Two virus groups Caulimo viruses and Gemini viruses, which have DNA genome are the most widely used DNA viruses for gene transfer. Retroviruses, Lentivirus and Adenovirus are also used widely in genetic engineering for gene transfer.

3. In-planta method:
This technique of gene transfer was developed by Failzadman and Markakes (1987). They kept Arabidopsis seed with genetically modified Agrobacterium and then raised the plants. Seeds obtained from these plants were germinated on antibiotic-free medium and identified the transformed plants.

Similarly, the apical meristematic part of embryo of germinated seeds can also be infected with Agrobacterium to produce genetically modified plants. In this method of gene transfer, the genes are directly transferred into a plant and for this reason, this technique is called In planta technique.

(2) Direct gene transfer:
In this method, the DNA of the desired gene(s) is transferred directly with some technique without involving any vector. Normally gene transfer by Agrobacterium is possible only in dicotyledons. In monocotyledons, which are chief cereals, gene transfer by Agroinfection is normally not possible.

For improvement in these plants and to incorporate desired features, new techniques for gene transfer have been developed, in which biological vectors are not required. Hence the techniques in which biological vectors such as Agrobacterium or viruses are not required are called direct gene transfer.

Direct gene transfer in plants can be done by the following methods:
1. Chemical mediated gene transfer: Certain chemicals like polyethene glycol (PEG), polyvinyl alcohol, calcium phosphate etc. induce DNA uptake into plant protoplasts Among chemical methods PEG is more commonly used chemical.

In this method, first plasmid DNA is mixed with protoplasts and after some time 15-25% PEG is added. This amount of PEG promotes DNA uptake in the protoplasts. The transformed protoplasts are cultured on selected medium and with the help of marker genes, the transformed protoplasts are selected.

Liposomes, diethyl aminoethyl (DEAE) and dextran proteins are also used for gene transfer in plants and animals. PEG directed gene transfer does not cause any harm to protoplasts.

2. Physical methods of Gene Transfer:
Direct gene transfer in plants is done effectively by several physical methods also. Some main physical methods are as follows.

  1. Gene gun: Gene gun is also known as particle gun, shotgun or microprojectile etc. By this technique, gene transfer is possible in the intact plant cells. (cells having intact cell wall). This technique of gene transfer was first used by Klein and Co-workers (1987) in onion cells for transferring DNA and viral RNA.
    RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture img 3
    In this process, the minute gold or tungsten particles of 1-3 mm diameter (microparticles) coated with desired DNA are shot (Bombarded) in the target cells with the help of microprojectile.
    These desired DNA coated gold or tungsten particles penetrate the cell wall and enter the cell where desired DNA incorporates with the host cell DNA and forms transgenic DNA. By the use of this method, gene transfer has been successfully achieved in wheat, rice, maize, tobacco and soybean etc. This technique is being used now in all type of plants worldwide.
  2. Electroporation: In this technique of gene transfer, the targeted protoplasts, plant cells or tissues are subjected to pulse of high voltage. As a result, minute temporary pores are formed in the plasmalemma (plasma membrane).
    The desired DNA enter through these minute pores. The target cells or the tissues are kept in a solution containing the desired DNA and then subjected to a high voltage pulse. The DNA from the solution first enters into the cells and then gets incorporated into the genome of the cells. This method is extensively used for transferring genes in the cells of monocotyledonous plants.
    RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture img 4
  3. Liposome mediated gene transfer: In this method of gene transfer, spherical lipid molecules filled with desired DNA and water are used for transferring genes. These DNA containing lipid capsules first stick to the plasmalemma (plasma membrane) and then fuse with it.
    The DNA present in these first enter into the cell and then enter the nucleus where it gets incorporated in the genome of the host cell. The liposome directed gene transferring technique also called as lipofection technique is a highly effective technique for transferring genes in bacteria, animal & plant cells
  4. Microinjection: In this method, genes are injected in plant protoplasts or cells with the help of glass needle of 0.5 – 1.0 mm diameter or micropipette directly in the cytoplasm or nucleus of the protoplasts or cells of plants. This is the suitable method of transferring genes in the isolated protoplasts.
    Note: Besides the above methods of gene transfer other methods are also employed for transferring genes. These are Ladder dependent gene transfer and Silicon carbide fibre dependent gene transfer.
    RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture img 5

RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture

Question 4.
Describe in brief various steps of tissue culture.
Answer:
Various Steps Of Tissue Culture:
Following steps are used in micropropagation method from the selection of explant until it is developed in to complete plant.
Zero Step: This step is divided into two parts:

  1. Selection of Explant and Pretreatment: Selection of explant depends on experimental requirements and objective of the experiment. For different objectives, selection of suitable explant is shown in the table below. Before surface sterilization, selected explants are washed under running water with the help of chemical Tween – 20; which cleans dust particles and microbes from its surface. This process is called Pretreatment of explants.
    RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture img 6
    Surface Sterilization of Explant: Various types of surface sterilization chemicals (disinfectants) are used such as Mercuric chloride (HgCl2), Ethanol, Silver nitrate (AgNO3), Bromine and Chlorine water. Selected explants are surface sterilized by appropriate disinfectants in Laminarair flow, which results in complete sterilization (Removal of all microbes) of explant.
    First Step: Initiation of Culture: Surface sterilized explant is transferred on a suitable nutrient medium and then transferred to the culture room. In a culture chamber, either callus or organ formation starts.

RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture

Question 5.
Write an illustrated account of physical methods of gene transfer.
Answer:
Physical methods of gene transfer are as follows:

  1. Gene gun method
  2. Electroporation
  3. Lipofection or Liposome mediated gene transfer
  4. Microinjection

1. Gene gun: Gene gun is also known as particle gun, shotgun or microprojectile etc. By this technique, gene transfer is possible in the intact plant cells. (cells having intact cell wall). This technique of gene transfer was first used by Klein and Co-workers (1987) in onion cells for transferring DNA and viral RNA.
RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture img 7
In this process, the minute gold or tungsten particles of 1-3 mm diameter (microparticles) coated with desired DNA are shot (Bombarded) in the target cells with the help of microprojectile.

These desired DNA coated gold or tungsten particles penetrate the cell wall and enter the cell where desired DNA incorporates with the host cell DNA and forms transgenic DNA. By the use of this method, gene transfer has been successfully achieved in wheat, rice, maize, tobacco and soybean etc. This technique is being used now in all type of plants worldwide.

2. Electroporation: In this technique of gene transfer, the targeted protoplasts, plant cells or tissues are subjected to pulse of high voltage. As a result, minute temporary pores are formed in the plasmalemma (plasma membrane).

The desired DNA enter through these minute pores. The target cells or the tissues are kept in a solution containing the desired DNA and then subjected to a high voltage pulse. The DNA from the solution first enters into the cells and then gets incorporated into the genome of the cells. This method is extensively used for transferring genes in the cells of monocotyledonous plants.
RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture img 8

3. Liposome mediated gene transfer: In this method of gene transfer, spherical lipid molecules filled with desired DNA and water are used for transferring genes. These DNA containing lipid capsules first stick to the plasmalemma (plasma membrane) and then fuse with it.

The DNA present in these first enter into the cell and then enter the nucleus where it gets incorporated in the genome of the host cell. The liposome directed gene transferring technique also called as lipofection technique is a highly effective technique for transferring genes in bacteria, animal & plant cells

4. Microinjection: In this method, genes are injected in plant protoplasts or cells with the help of glass needle of 0.5 – 1.0 mm diameter or micropipette directly in the cytoplasm or nucleus of the protoplasts or cells of plants. This is the suitable method of transferring genes in the isolated protoplasts.

Note: Besides the above methods of gene transfer other methods are also employed for transferring genes. These are Ladder dependent gene transfer and Silicon carbide fibre dependent gene transfer.
RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture img 9

RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture

Question 6.
Describe different steps of micropropagation.
Answer:
Micropropagation:
Following steps are used in micropropagation method from a selection of explant till it is developed in to complete plant.
Zero Step: This step is divided into two parts:

  1. Selection of Explant and Pretreatment: Selection of explant depends on experimental requirements and objective of the experiment. For different objectives, selection of suitable explant is shown in the table below. Before surface sterilization, selected explants are washed under running water with the help of chemical Tween – 20; which cleans dust particles and microbes from its surface. This process is called Pretreatment of explants.
    RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture img 10
  2. Surface Sterilization of Explant: Various types of surface sterilization chemicals (disinfectants) are used such as Mercuric chloride (HgCl2), Ethanol, Silver nitrate (AgNO3), Bromine and Chlorine water. Selected explants are surface sterilized by appropriate disinfectants in Laminarair flow, which results in complete sterilization (Removal of all microbes) of explant.
    Fourth Step: Transplantation: Hardening and acclimatization of tissue culture raised plants as they are tender. Subsequent transplantation to the greenhouse or field.

RBSE Solutions for Class 12 Biology Chapter 16 Plant Tissue Culture

Question 7.
What are the different components of an ideal culture medium? Explain.
Answer:
An ideal culture medium should contain all the mineral nutrients required for plant growth. The most commonly used culture medium is M.S. medium proposed by Murashige and Skoog (1962).
The basic components of an ideal culture medium are as follows:
Basic Composition of culture medium.

  1. Vitamins: B1, B3, B5 and B6
  2. Amino acid-Glycine (Simplest)
  3. Complex Nutrients
    • Casein hydrolysate
    • Coconut milk
    • Malt extract
    • Tomato juice
    • Yeast extract
    • Corn milk
  4. Phyto hormones – Such as –
  5. Auxins – Root Differentiation
    • Indole butyric acid
    • Naphthalene acetic acid
    • Napthoxy acetic acid

RBSE Solutions for Class 12 Biology