Chapter-Plant Cell

(c)

Explanation. The plant cell culture is based on a unique property of the cell-totipotency (L. totus=entire, potentia=power) and it may be defined as the ability of a plant cell to regenerate into whole plant.

(a)

Explanation. Regeneration of whole plant from cultured plant tissue is called in vitro morphogenesis.

(b)

Explanation. A somatic embryo is an embryo derived from a somatic cell, other than zygote, usually on culture in vitro, and the process is known as somatic embryogenesis.

(c)

Explanation. Gottieb Haberlandt described the cultivation of mesophyll cells of Lamium purpureum and Eichhornia crassipes, epidermal cell of Ornithogalum and hair cells of Pumonaria. These calls survived for 3-4 weeks. Gottieb Haberlandt is regarded as the ‘father of tissue culture’ due to this endeavor.

(a)

Explanation. Work on tissue culture was started in India during mid 1950s at the Department of Botany (University of Delhi) by Panchanan Maheshweri who regarded a ‘father of embryology’ in India.

(c)

Explanation. In vitro gene banks: it has been made to preserve the genetic resources by non-conventional methods (i.e. cell and tissue culture methods).

(b)

Explanation. Explant culture is a technique used for the isolation of cells from a piece or pieces of tissue. Tissue harvested in this manner is called an explant. It can be a portion of the shoot, leaves, or some cells from a plant, and can be any part of the tissue from an animal.

(d)

Explanation.Tissue culture enables rapid vegetative propagation of plants using small amounts of tissue as explant; this is usually called micropropagation.

(a)

Explanation.Breeding assisted by molecular (nucleic acid) markers, is known as molecular breeding. A molecular marker describes a molecular feature that can be identified particular locations in the genome.

(b)

Explanation.Many bacteria accumulate polyhydroxy butyrate (PHB), which is used to produce a biodegradable plastic.

(a)

Explanation. Polyethylene Glycol (PEG) is the most important, widely used and most successful method for protoplast fusion and it induce DNA uptake into plant cell.

(b)

Explanation. Diploid cells have two homologous copies of each chromosome, usually one from the female and one from the male.

(b)

Explanation. Somatic hybrids and cybrids are not produced through sexual fertilization. These are produced through fertilization of somatic cells.

(d)

Explanation. The techniques of somatic hybridization involves four steps-

a. Isolation of protoplast

b. Fusion of protoplast of desired species/varieties

c. Selection of somatic hybrid cells

d. Culture of hybrid cells and regeneration of hybrid plants from them.

(a)

Explanation. Triploid plants raised by endosperm culture show seed sterility or seedlessness. This characteristic increases edibility of fruits and desirable in plants like citrus, apple, banana and pear.

(b)

Explanation. Micropropagation is used to multiply novel plants, such as those that have been genetically modified or bred through conventional plant breeding methods.

(c)

Explanation.The explants can be any part of the plant like leaf, hypocotyls, cotyledons and the piece of stem etc. It is used for induction or regeneration of plants.

(c)

Explanation. These are essential inorganic nutrients for plant growth which are divided in to two categories-

1. Macronutrients-N, P, K, Ca, Mg and S

2. Macronutrients-Zn, Fe, Mn, B, Mo and Cu

(a)

Explanation.The plant cell culture is based on a unique property of the cell-totipotency (L. totus=entire, potentia=power).

(d)

Explanation. After hardening process plantlets are transferred to green house or field conditions.

(a)

Explanation.In electroporation, a pulse of high voltage is applied for protoplast/tissue/cell, which makes transient pores in the plasma membrane, which facilitates the uptake of foreign DNA. Using this process, transient expression of foreign DNA has been demonstrated in wheat, rice and maize.

(c)

Explanation.Weed decrease crop yields and quality primarily by competing with crop plants for water, light and nutrients. There are certain herbicides, which are used as pre-emergence stage to kill weeds before planting the crop.

(c)

Explanation.The cry gene of Bacillus thuringiensis (Bt gene) was found to express proteinaceous toxin inside the bacterial cells. When specific insects ingest the toxin, they are killed.

(b)

Explanation. This process is utilizes the long-term preservation of tissues and cells at ultra-low temperature i.e. in liquid nitrogen (-196⁰C) by using cryoprotectants e.g. glycerol, proline, dimethylsulfoxide and mannitol.

(a)

Explanation. This process is used for short or medium term storage of germplasm. The storage of germplasm by using nodal or meristem explant culture, shoot tip, under conditions that impose slow growth (such as low temperature 4⁰C or 15⁰C) and nutrient limitation.

(c)

Explanation. Agrobacterium tumefaciens bacteria is also known as natural genetic engineer of plants due to its natural ability of DNA transfer.

(a)

Explanation. This bacterium is also known as natural genetic engineer of plants due to its natural ability of DNA transfer. Gene transfer through Agrobacterium is achieved by its co- culture with tissue explants.

(c)

Explanation.Agrobacterium tumefaciens consists of Ti-plasmid, which is directly responsible for tumour induction. Transfer of small DNA segment (T-DNA) from Ti- plasmid and its integration into host genome induces tumour formation in plants.

(d)

Explanation. This technique has been used to produce virus resistant varieties of potato, papaya and tomato etc.

(c)

Explanation. Based on insecticidal activities against insects, the insecticidal toxin of Bacillus thuringiensis has been classified into the four major classes: cry I, cry II, cry III and cry IV. They do not harm to silkworm and butterflies or other beneficial insects.

(a)

Explanation. Blocking or reducing ethylene production can slow therefore ripening down. This can be achieved by introducing ethylene forming gene(s) in a way that will suppress its own expression in the crop plant.

(b)

Explanation. In the USA a transgenic tomato named FlavrSavr (Flavour Saver) was produced where ripening is delayed by lowering polygalacturonase activity.

(c)

Explanation. Plant leaves are the most convenient and popular source of plant protoplast due to their uniformity.

(d)

Explanation. Genetic variation arises in cultured plant cell and is present in the plants regenerated from them and in the progeny from these plants. This variation is called somaclonal variation.

(a)

Explanation. Roundup Ready crop plants tolerant to the most extensively used herbicide-Roundup, has already been commercialized.

(c)

Explanation. The cry gene of Bacillus thuringiensis (Bt gene) was found to express proteinaceous toxin (b- endotoxin) inside the bacterial cells. When specific insects ingest the toxin, they are killed.

(b)

Explanation. The inducing agent is called ‘Fusogen’. Polyethylene Glycol (PEG) is the most important, widely used and most successful method for protoplast fusion.

(c)

Explanation. There are some plants that resist drought conditions. The plants naturally check the property of resistance against water loss from the surface of plants. A specific gene called drought resistance gene or DR gene controls this special feature.

(d)

Explanation. Stress is either abiotic or biotic in nature. Abiotic stress is due to nonliving factors i.e. drought, herbicide etc. and biotic stress is produced by a living organism (e.g. a virus, an insect and a bacterium etc.).

(a)

Explanation. In such a case, the plants serve the purpose of bioreactors, to modify or new compounds such as amino acids, vitamins, proteins and pharmaceuticals etc. for food industries or so on.The cultivation of such plants is called molecular farming.

Animal Cell Culture and Applications

(b)

The surface for experiments is sterilized by sodium hypochorite, which is used as a disinfectant.

(a)

The gelling agent in culture medium is agar. Agar is a polysaccharide obtained from red algae, Gelidium amansii.

(d)

The most widely used nutrient medium is MS medium, which was developed by Murashige and Skoog in 1962.

(c)

Agar is a polysaccharide obtained from red algae, Gelidium amansii. It is used as a gelling agent that helps in solidification of the liquid medium.

(b)

Agar is used as a gelling agent that helps in solidification of the liquid medium.

(b)

Sub-culturing means transfer of callus cells to new medium in a new tube. Callus culture can be maintained for prolonged periods by repeated sub-culturing.

(b)

The enzymes pectinase/ macerozyme are used to isolate single cell from either callus or any other plant part. These enzymes dissolve the middle lamella to release single cell.

(c)

In mass cell culture the plant cells can be cultured in specially designed bioreactors. These reactors do not have stirrers.

(c)

In mass cell culture the plant cells can be cultured in specially designed bioreactors. These reactors do not have stirrers as plant cells are shear sensitive.

(b)

The enucleated and nucleated protoplasts are fused to create cytoplasmic hybrids or cybrids.

(d)

In mass cell culture the plant cells can be cultured in specially designed bioreactors. These reactors do not have stirrers as plant cells are shear sensitive. In place of stirrer, gas is used, as it provides stirring as well as oxygen.

(c)

Protoplasts are plant cells without cell wall. As protoplasts lack cell wall, it can be easily utilized for creating cybrids.

(d)

Miller and Skoog proved that formation of root or shoot depends on the relative concentration of auxin and cytokinin. If, auxins are in high concentration, then it promotes rooting and if, cytokinins are high, then shoot is formed.

(a)

Micro-propagation can be done by culture of apical shoots, axillary buds and meristems in suitable nutrient medium.

(c)

Micro-propagation can be done by culture of apical shoots, axillary buds, and meristems in suitable nutrient medium. It is very rapid method and is used for the commercialization of many seedless and ornamental plants.

(a)

The distribution of viruses in plants is uneven but generally the apical and axillary meristems are free from viral particles.

(b)

The embryos are encapsulated in protective chemicals like calcium alginate. This chemical prevents the embryos from desiccating.

(c)

It is difficult to produce hybrids by inter-specific and inter-genetic crosses because of abnormal development of the endosperm, which causes premature death of hybrid embryos.

(a)

The embryo of sterile hybrids seeds can be excised at an appropriate time and can be cultured on a suitable nutrient medium to produce novel hybrids. This process is known as embryo rescue.

(b)

The somatic cell hybridization is also known as para-sexual hybridization. This method offers an alternative method for obtaining somatic hybrids.

(a)

Somatic hybrids or para-sexual hybrids would never be formed in nature through sexual fertilization.

(b)

The first inter-specific somatic hybrid was formed in 1972 between Nicotiana glauca and N. langsdorffii.

(c)

Secondary metabolite are used in defense mechanism in plants e.g. alkaloids, resins etc. Taxol is alkaloid that is produced by Taxus spp. It is used as anti-carcinogenic compound.

(c)

Secondary metabolite are used in defense mechanism in plants e.g. alkaloids, resins etc. Azadirachtin is used as an insecticide, it is the product of neem tree i.e. Azadirachta indica.

(d)

In 1981 Larkin and Scowcroft proposed the term somaclones for plant variants, which are obtained from tissue cultures of somatic tissues.

(a)

The in vivo gene bank preserve the genetic resources by conventional methods and in vitro gene banks preserves the genetic resources by non-conventional methods like cell and tissue culture methods.

(d)

In Cryopreservation the cells and tissues are stored at ultra-low temperature i.e. –196°C in liquid nitrogen.

c) Liquid nitrogen is used in cryopreservation of cells and tissues at ultra-low temperature i.e. –196°C.

(c)

Cryopreservation utilizes the long-term preservation of tissues and cells at ultra-low temperature i.e. in liquid nitrogen (-196⁰C) by using cryoprotectants e.g. glycerol, proline, dimethylsulfoxide and mannitol.

(c)

The gene of interest is flanked by the controlling sequences, which are promoter and terminator. These sequences are very necessary for gene transfer.

(a)

Agrobacterium tumefaciens is a natural genetic engineer of plant that has the natural ability to transfer T-DNA of their plasmid.

(d)

Crown gall is an unorganized growth of a cell mass at the wound site that is formed upon infection of cells.

(b)

The transgenic plants can be confirmed by molecular techniques like PCR and southern blot hybridization.

(a)

Calgene introduced the nitrilase gene in cotton to control weed.

(c)

Antisense gene is used to delay ripening in tomato. The developer is Calgene.

(c)

Weeds are the plants that grow, where they are not wanted. Weeds grow especially with crop plants and decrease the yield and quality of crops by competing with crop plants e.g. Striga.

(d)

Herbicide-round up is commercialized in markets and roundup ready crop plants are tolerant to this herbicide.

(a)

The first gene available for genetic engineering of crop plants for pest resistance was Cry genes. They are also called Bt genes.

(b)

Flavr Savr is a transgenic tomato that was commercialized in U.S.

(b)

Golden rice is genetically engineered rice developed by Prof. Ingo Potrykus and Dr. Peter Beyer. This rice is enriched in pro-vitamin A.