#1
29th November 2014, 08:07 AM
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Maharashtra State Board 12th class science Solve question papers
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#2
29th November 2014, 09:49 AM
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Re: Maharashtra State Board 12th class science Solve question papers
You are searching for the Maharashtra State Board 12th class science Solve question papers. Here I am uploading a file that contains the Maharashtra State Board 12th science Solve question papers. You can download it from here. These are as follows: |
#3
30th September 2019, 07:53 AM
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Re: Maharashtra State Board 12th class science Solve question papers
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#4
30th September 2019, 07:53 AM
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Re: Maharashtra State Board 12th class science Solve question papers
As you are asking for Maharashtra State Board 12th class science Solve question papers, so on your demand I am providing same here : Q. What is leaching? Ans. It is a process where the water soluble nutrients go down into the soil layers and get locked as unavailable salts. Q. Enlist the basic steps involved in recombinant DNA technology. Ans. Given below are the basic steps involved in recombinant DNA technology: Identification and isolation of gene of interest Joining of this gene into a suitable vector (construction of recombinant DNA) Introduction of this vector into a suitable organism Selection of transformed recombinant cells with gene of interest Multiplication or expression of the gene of interest Q. Describe different steps involved in tissue culture technique. Ans. There are three main steps involved in tissue culture technique, which are described below: (i) Explant culture: Proper explant is excised from the plant which may be a cell, tissue or a piece of the plant organ. Generally, parenchyma tissue or meristem is used as explants. The cells from explant absorb nutrients and start multiplying to form callus. Callus is the unorganised mass of cells. (ii) Sterilization: In tissue culture technique, different apparatus, the medium used and the explant also is to be properly sterilized to avoid the contamination due to which the experiment may fail. The methods used for sterilization may be dry or wet sterilization, Alcohol sterilization etc. The explants used can be sterilized by using 1% sodium hypochlorite or 70% ethyl alcohol or 10% hydrogen peroxide. (iii) Organogenesis: Now the growth hormones like auxins and cytokinins in proper proportion are provided to the callus to induce the formation of organs. If auxins are more, roots are formed (rhizogenesis) and if the cytokinins are in more quantity then the shoot system begins to develop (caulogenesis). Q. State any two symptoms of Downs syndrome. Ans. Symptoms of Down syndrome as observed in children are as follows: (any two) Face tends to be round and flat with small and low-set nose. The nose may be small with a flat and low bridge. The back of the head (called the occiput) is slightly flattened. Eyes slant upwards and have an extra fold of skin (epicanthic fold) on the upper eyelid. This skin fold covers the inner corner of the eye. Mental retardation Q. Describe the histology of ‘human testis. Ans. The testis are retroperitoneal from the time of development, until they descend into their final adult position in the scrotum. The testes hang in suspension attached to the spermatic cord and are covered externally by the loose, wrinkly, pigmented skin known as the scrotum. Just inside the scrotum, there are three more distinguishable layers that protect the testicular tissue. (i) Tunica vaginalis: It is the outermost incomplete peritoneal covering made up of connective tissue and epithelium. (ii) Tunica albuginea: It is the middle layer formed by fibrous connective tissue. (iii) Tunica vasculosa: It is the innermost layer formed of delicate connective tissue, supporting a network of blood capillaries. |