Science (English Medium) इयत्ता १२ - CBSE Important Questions

State the medicinal value and the bioactive molecules produced by Streptococcus, Monascus and Trichoderma.

Given below is a list of six micro-organisms. State their usefulness to humans.

1. Nucleopolyhedrovirus
2. Saccharomyces cerevisiae
3. Monascus purpureus
4. Trichoderma polysporum
5. Penicillium notatum
6. Propionibacterium sharmanii

Explain the significant role of the genus Nucleopolyhedrovirus in an ecological sensitive area.

How do methanogens help to generate biogas?

Organic farmers prefer the biological control of diseases and pests to the use of chemicals for the same purpose. Justify

Can we use slurry of human excreta instead of cowdung slurry to produce biogas in a typical biogas plant? Support your answer giving reasons.

Study the given diagram of the Sewage Treatment  Plant (S.T.P.) and answer the question that follows:

1. Which one of the two 'S.T.P.' (A) or (B) will be more effective in treating the human excreta in municipal waste?
2. Write the steps followed in carrying the treatment of the sewage in step (Z), once the BOD of sewage is reduced significantly till it is passed on to the "anaerobic sludge digesters".

Name the drug a patient who has undergone a successful organ transplant, has to take all his/her life.

Farmers are often suggested to use the following organism in their crop land so as to improve the soil fertility. Explain.

Rhizobium

Farmers are often suggested to use the following organism in their crop land so as to improve the soil fertility. Explain.

Anabaena 

Given below are the list of the commercially important products and their source organisms. Select the option that gives the correct matches. 

Retroviruses have no DNA. However, the DNA of the infected host cell does possess viral DNA. How is it possible?

Rearrange the following in the correct sequence to accomplish an important biological reaction:

(a) In vitro synthesis of copies of DNA of interest

(b) Chemically synthesized oligonucleotides

(c) Enzyme DNA-polymerase

(d) Complementary region of DNA

(e) Genomic DNA template

(f) Nucleotides provided

(g) Primers

(h) Thermostable DNA-polymerase (from Thermus aquaticus)

(i) Denaturation of ds-DNA

Mention the type of host cells suitable for the gene guns to introduce an alien DNA.

Suggest a technique to a researcher who needs to separate fragments of DNA.

Suggest and describe a technique to obtain multiple copies of a gene of interest in vitro.

Draw a labelled sketch of sparged-stirred-tank bioreactor. Write its application.

Name the enzymes that are used for the isolation of DNA from bacterial and fungal cells for recombinant DNA technology.

How does a restriction nuclease function? Explain

Name and describe the technique that helps in separating the DNA fragments formed by the use of restriction endonuclease