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Although a prokaryotic cell has no defined nucleus, yet DNA is not scattered throughout the cell. Explain. Ans. DNA (being negatively charged) is held with some proteins (that have positive charges) in a region termed as ‘nucleoid’. The DNA in nucleoid is organised in large loops held by proteins. Also the DNA in form of single chromosomes is attached to mesosome at a point.

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Following are the analogous structure from the given list : (i) Wings of butterfly and birds. (ii) Tubers of sweet potato and potato.

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A nematode is a type of parasitic worm. Meloidegyne incognitia infects the roots of tobacco plants, reducing production dramatically. A novel strategy was adopted to prevent thisi nfestation which as based on the process of RNA inteference (RNAi). Nematode-specific genes were delivered into the host plants using Agrobacterium vectors. In the host cells, DNA was introduced in such a way that it produced both sense and anti-sense RNA. Because these two RNAs were complementary, they generated a double-stranded (dsRNA) that triggered RNAi and silenced specific nematode mRNA. As a result, the parasite was unable to live in a transgenic host that expressed particular interfering RNA. The transgenic plant so found itself protected from the parasite

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Yes. India has greater ecosystem diversystem diversity than norway having deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, and alphine meadows. (b) Write the difference between genetic biodiversity and species biodiversity that exists at all the levels of biological organisation. (b) Genetic diversity : (i) Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. (ii) A single species might show high diversity at the genetic level (E.g. Man : Chinese, Indian American, African etc.) India has more than 50,000 genetically different strains of rice, and 1,000 varieties of mango. (iii) Genetic diversity allows species to adapt to changing environments. This diversity aims to ensure that some species survive drastic changes and thus carry on desirable genes. Specific diversity : (i) It is the ratio of one species population over total number of organisms across all species in the given biome.‘Zero’would be infinite diversity,and‘one’represents only one species present. i) Species diversity is a measure of the diversity within an ecological community that incorporates both species richness (the number of species in a community) and the eveness of species. (iii) For example, the Western Ghats have a greater amphibian species diversity than the Eastern Ghats. There are more than 2,00,000 species in India of which several are confined to India (endemic).

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In birds, sex determination is of ZW – ZZ type. In this type the males are homogametic and have ZZ sex chromosomes, and females are heterogametic with ZW pair of sex chromosomes. If Parents are male (ZZ), the gametes will be Z and Z and in females (ZW), gametes are Z and W. The offspring can have the genetic configuration as ZW and ZZ whereas, in human beings, the chromosomal mechanism of sex determination is of XX – XY type. The human male is heterogametic and have XY sex chromosomes and human female is homogametic with XX sex chromosome

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In birds, ZW-ZZ type of sex determination is followed. The males are homogametic (ZZ) and females are heterogenetic (ZW). In The F1 generation, ZW(female) and ZZ (male) are formed.

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Out-breeding : Out-breding is the breeding of the unrelated animals, which may be between individuals of the same breed but having no common ancestors for 4-6 generations (out-breeding) or between different breeds (cross-breeding) or different species (inter-specific hybridisation). Out-crossing : This is the practice of mating of animals within the same breed, but having no comon ancestors on either side of their pedigree up to 4-6 generations. The offspring of such a mating is known as an out- cross. It is the best breeding method for animals that are below average in productivity in milk production, growth rate in beef cattle, etc. A single outcross often helps to overcome inbreeding depression. Cross-breeding : In this method, superior males of one breed are mated with superior females of another breed. Cross - breeding allows the desirable qualities of two different breeds to be combined. The progeny hybrid animals may themselves be used for commercial production. Alternatively, they may be subjected to some form of inbreeding and selection to develop new stable breeds that may be superior to the existing breeds. Many new animal breeds have been developed by this approach. Hisardale is a new breed of sheep developed in Punjab by crossing Bikaneri ewes and Marino rams.

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a) Chemical methods often kills both useful and harmful life forms indiscriminately. Eradication of the creatures that are often described as pests in not only possible, but also undersirable, for without them the beneficial predatory and parasitic insects which depend upon them as food or hosts would not be able to survive. (b) Insects = Ladybird and Dragonflies. Bacteria = Bacillus thuringiensis. Fungus = Trichoderma

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Small volume cultures cannot yield appreciable quantities of products. To produce in large quantities, the development of bioreactors, where large volumes (100 - 1000 litres) of culture can be processed, was required. Thus, bioreactors can be thought of as vessels in which raw materials are biologically converted into specific products, individual enzymes, etc., using microbial plant, animal or human cells