CBSE Biotechnology sample paper class XII 2006

www.cbseguess.com ------------------------------------------------------------------------------------------------------------www.cbseguess.com Other Educational Portals www.icseguess.com | www.ignouguess.com | www.dulife.com | www.magicsense.com Biotechnology Class XII Time: 3 hours Max Marks: 70 SECTION-A (1x5=5) 1. Give any two examples of hydrophobic amino acids. 2. Define exons. 3. Expand RAPD. 4. Name the organism used commercially to produce citric acid. 5. How does DMSO act as cryoprotectant? SECTION-B (2x10=20) 6. Explain briefly any 2 DNA transfer methods into host cell. 7. Write about any four precautions one should take for maximum protein stability during purification. 8. A person suffering from gonorrhoea recovered quickly by constantly having whey protein in his diet. What could be the reason for this? 9. Gene probe labeling using random priming uses combinations of oligonucleotides of 6 bp length. Calculate the number of possible random combinations if all the four nucleotides are included. 10. A lab technician was trying to observe Cos-7 cell line plate under compound light microscope and couldn’t appreciate the cell line. Why? 11. Differentiate between EST and GST. 12. What is the use of magnesium ions in PCR? Give any 3 applications of PCR. 13. Three bacterial colonies each having 106 cells was completely scraped and dissolved in an eppendorf for isolation of proteins. This pool of bacterial colonies was pelleted. Find out the packed cell volume in millilitres if the bacteria is rod shaped with diameter 1μm and height 2μm. 14. What are stem cells? What is their role in the field of biotechnology? 15. Why are blue colonies formed by the cell transformed with pUC 18 in an X-gal, IPTG, LB plate? www.cbseguess.com ------------------------------------------------------------------------------------------------------------www.cbseguess.com Other Educational Portals www.icseguess.com | www.ignouguess.com | www.dulife.com | www.magicsense.com SECTION-C (3x10=30) 16. Why is aeration important for microbial growth? How can proper aeration be achieved in the microbial cultures grown in the laboratory? 17. What is micropropagation? List the steps involved in it. 18. A plasmid vector has restriction sites for only BamHI and EcoRI. BamHI recognizes the sequence  below and cleaves at 5’ GGATCC 3’the position indicated by the arrows. EcoRI recognizes and 3’ CCCAGG 5’   cleaves the following sequence 5’ GAATTC 3’. Explain with the help of a diagram which of these 3’ CTTAAG 5’  two restriction enzymes you would use to cut the plasmid vector in order to join DNA fragment that has been digested with Sau3A which has a recognition sequence 5’ GATC 3’ 3’ CTAG 5’ 19. What does molecular breeding mean? Explain with examples the type of markers used in screening and selection. 20. Given a tomato callus, how would you go about preparing artificial seeds for commercial use? 21. The study of bacterial growth curve shows that in exponential phase or the log phase the concentration of microbial biomass increases from X0 to X in time ‘t’ having a specific growth rate ‘μ’. Prove that X=X0 eμt. 22. What is BLAST? Enlist the principles involved in it. 23. Differentiate between pBR322 and pUC19. What are the possible sites where the gene of interest can be inserted in pUC19? How can this be screened? 24. Human haemoglobin is a tetramer having 2α and 2β subunits. How many bands you will observe if you run this in SDS-PAGE and native PAGE? Justify your stand. www.cbseguess.com ------------------------------------------------------------------------------------------------------------www.cbseguess.com Other Educational Portals www.icseguess.com | www.ignouguess.com | www.dulife.com | www.magicsense.com 25. What are the main areas of consideration for safety aspects specific to microbial biotechnology? OR A bacterial medium contains 103 cells/cc in the beginning and it enters the log phase having specific growth rate 207/minute. Calculate the increase in biomass after three hours and the doubling time. SECTION-D (5x3=15) 26. What is the fate of ions of high molecular mass and low molecular mass in the deflection chamber of a mass spectrometer and how are these ions detected in a detector of a mass spectrometer? Enlist the 4 advantages of using a mass spectrometer. OR Study the following enzyme purification table and answer the question that follow: Procedure total protein (mg) total activity (units) step1: crude extract 1000 2000 step2: precipitation {salt} 200 1890 step3: ion exchange chromatography 100 1500 step4: gel chromatography 90 1400 step5: affinity chromatography 2 1000 i] What is the yield of active protein from crude extract? ii] Write the specific activity for all the 5 steps? iii] Write the overall yield for all the 5 steps? iv] Which step in the purification is least effective and why? v] Which step in the purification is the most effective and why? 27. Give a brief account on types of cell lines. How can you differentiate a cancer cell culture from normal cell culture. 28. A 41 year old women had come to the cancer research institute, Adyar, Chennai, concerned about the lump in her right breast. A biopsy and a mammogram confirmed that a cancer is present. The doctor suggested for a lumpectomy followed by radiation www.cbseguess.com ------------------------------------------------------------------------------------------------------------www.cbseguess.com Other Educational Portals www.icseguess.com | www.ignouguess.com | www.dulife.com | www.magicsense.com treatment and adjunct therapy with anticancer drugs for which the level of gene expression has to be studied. As a biotechnologist, suggest a best method to study the level of gene expression for this patient and systematically scheme the steps involved. OR 29. Bio-informatics databases provide many different types of sequences, such as cDNA, genomic, EST, GST, peptide,etc. which of these would you use as the most suitable starting point for identifying: a)repressor b) insulin c) exon d) cDNA library e) constitutive gene