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The most commonly used bioreactors are of stirring type. A stirred - tank reactors is usually cylindrical or with a curved base to facilitate the mixing of the reactor contents. The stirrer facilitates even mixing and oxygen availability throughout the bioreactor. The bioreactor has an agitator system, an oxygen delivery system and a foam control system, a temperature control system. pH control system and sampling ports so that small volumes of the culture can be withdrawn periodic

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a) Restriction enzymes : 1. Restriction enzymes belongs to class of enzymes nucleases which breaks nucleic acids by cleaving their phosphodiester bonds. 2. Since Restriction endonucleases cuts DNA at specific recognition site,they are used to cut the donor DNA to isolate the desired gene. 3. The desired gene has sticky ends which can be easily ligated to cloning vector cut by same restriction enzymeshavingcomplementarystickyendstoformrecombinantDNA. (1mark) 4. An example is EcoR1 which is obtained from E.coli bacteria “R” strain which cuts DNA at specific palindromic Recognition site. 5‘GAATTC3‘ 3‘ CTTAAG 5‘ (b) Plasmids : 1. Plasmids are autonomous,extra chromosomal circular double stranded DNA of bacteria 2. Since they are small and self replicating,they are used as cloning vectors in genetic engineering. 3. Some plasmids have antibiotic resistance genes which can be used as marker genes to identify recombinant plasmids from non recombinant ones. 4. The plasmids are cut and ligated with desired genes and transformed into host cell for amplification to obtain the desired products. 5. An example of artificial modified plasmids are pBR322 ( constructed by bolivar and rodriguez) or pUC.

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To produce fruits, most plants require pollination and fertilisation. Some plants, on the other hand, can bear fruit before or after fertilisation. Parthenocarpy is the process of producing fruits in plants from unfertilized ovules. Prior to fertilisation, unfertilized ovules develop into fruits. There are no seeds in these fruits. Parthenogenesis is a kind of reproduction that is seen in a variety of organisms, primarily invertebrates and lower plants. It is a process in which an unfertilized ovum develops into an individual without being fertilised (virgin birth). As a result, it might be classified as an asexual reproduction process. Rotifers, honeybees, and even some lizards and birds exhibit this trait (turkey). Parthenogensis differs from parthenocarpy in that parthenogensis is demonstrated by animals and plants while parthenocarpy is shown only by plants. 

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Yes, i do agree with the fact that breastfeeding is the best for newborn babies. Mammary glands start producing milk at the end of pregnancy. The milk produced during the initial few days and lactation is called COLOSTRUM which contains several antibodies. It helps in developing resistance for newborn baby. It helps the baby fight of viruses and bacteria. Thus breast milk is packed with disease-fighting substance that protect your baby from illness. Breast milk also naturally contains many of the vitamins and minerals that a newborn requires. Also, it is easily digested - no constipation, diarrhea and upset stomach.

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1. VNTR stands for “Variable Number of Tandem Repeats”. The VNTR belongs to a class of satellite DNA referred to as mini-satellite. A small DNA sequence is arranged tandemly in many copy numbers. The copy number varies from chromosome to chromosome in an individual. The numbers of repeat show very high degree of polymorphism. As a result th size of VNTR varies in size from 0.1 to 20 kb. Consequently, after hybridization with VNTR probe, the autoradiogram givesmanybandsofdifferingsizes.Thesebandsgive characteristicpatternforanindividualDNAwhichis used to identify individuals.

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(b) Since DNA from every tissue (such as blood, hair - follicle , skin, bone, saliva, sperm etc.), from an individual show the same degree of polymorphism, they become very useful identification tool in forensic applications to identify criminals. Further, as the polymorphisms are inheritable from parents to children, DNA fingerprinting is the basic of paternity testing, in case of disputes.

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a) Two causes of air pollution (1) Burning of fossil fuels. (2) Smoke released from vehicles. (3) Industrial effluents (4) Smoke stacks of thermal power plants. (b) Harmful effects of air pollution. (1) It affects respiratory system of humans and of animals. (2) It also reduces growth and yield of crops & cause premature death of plants. (c) (1) Encouraging public transport i.e. buses & using CNG instead of diesel. (2) Planting more trees to curb pollution.

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Drosophila melanogaster : Morgan carried out several dihybrid crosses in Drosophila to study gens that were sex-lined. Morgan and his group knew that the genes were located on the X chromosome and saw quickly that when the two genes in a dihybrid cross were situated on the same chromosome, the proportion of parental gene combinations were much higher than the non-parental type. Morgan attributed this due to the physical association or linkage of the two genes and coined the term linkage to describe this physical association of genes on a chromosome and the term recombination to describe the generation of non-parental gene combination. Morgan and his group also found that even when genes were grouped on the same chromosome, some genes were very tightly linked (showed very low recombination) while others were loosely linked

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b) Morgans student Alfred Sturtevant used the frequency of recombination between gene pairs on the same chromosome as a measure of the distance between genes and ‘mapped’ their position on the chromosome. Today genetic maps are extensively used as a starting point in the sequencing of whole genomes.