Extra Questions for Class 12 Biology Chapter 11 Biotechnology Principles and Processes
Q.1. Mention the uses of cloning vector in biotechnology.
Ans. Cloning vectors are used for transferring fragments of foreign DNA into a suitable host. They are also used to select recombinants from non-recombinants.
Q.2. Identify the reason for selection of DNA polymerase from Thermus aquaticus for Polymerase Chain Reaction.
Ans. DNA polymerase from Thermus aquaticus remains active during the high temperature induced denaturation of double stranded DNA.
Q.3. What are palindromes?
Ans. Palindromes are group of letters (sequences) that read same both in forward and backward
Q.4. Name the compound used for staining the isolated DNA in the gel electrophoresis.
Ans. Ethidium bromide.
Q.5. How can bacterial DNA be released from the bacterial cell for biotechnology experiments?
Ans. The bacterial cell wall is digested by the enzyme lysozyme to release DNA from the cell.
Q.6. What is recombinant DNA?
Ans. Recombinant DNA is the DNA formed by combining DNAs from two different organisms.
Q.7. Write the two components of the first artificial recombinant DNA molecule constructed by Cohen and Boyer.
Ans. The two components were – antibiotic resistance gene and plasmid vector of Salmonella
Q.8. What is the host called that produces a foreign gene product? What is this product called?
Ans. The host that produces a foreign gene product is called competent host. The product is called recombinant protein.
Q.9. Give any two microbes that are useful in biotechnology.
Ans. E. coli and Saccharomyces cerevisiae.
Q.10. What is the function of restriction enzyme?
Ans. To cut DNA at specific site.
Q.11. How is repetitive/satellite DNA separated from bulk genomic DNA for various genetic experiments?
Ans. By density gradient centrifugation.
Q.12. Name the first plasmid used as vector.
Q.13. Write the name of the enzymes that are used for isolation of DNA from bacterial and fungal cells respectively for Recombinant DNA technology.
Ans. Bacterial cell is treated with enzyme lysozyme.
Fungal cell is treated with chitinase.
Q.14. Biotechnologists refer to Agrobacterium tumifaciens as a natural genetic engineer of plants. Give reasons to support the statement.
Ans. This is because A. tumifaciens can transfer genes naturally by delivering a piece of T-DNA to plant cells. It has a tumour inducing plasmid.
Q.15. Why is the enzyme cellulase needed for isolating genetic material from plant cells and not from the animal cells?
Ans. The enzyme cellulase breaks down cellulose which is present in cell walls of plants but absent in animal cells.
Q.16. What is gene gun?
Ans. The instrument for bombarding micro-projectile particles (gold/tungsten particles) coated with foreign DNA, with great velocity, into a target cell is called gene gun.
Q.17. What is the cell that receives a recombinant gene called?
Ans. Competent host cell/recipient cell.
Q.18. How does an alien DNA gain entry into a plant cell by ‘biolistics’ method?
Ans. In biolistics method, cells are bombarded with high velocity micro-particles of gold or tungsten coated with DNA.
Q.19. Name the host cells in which micro-injection technique is used to introduce an alien DNA.
Ans. Animal cells.
Q.20. Why EtBr is used in gel electrophoresis inspite of it being highly carcinogenic?
Ans. Ethidium bromide (EtBr) exchanges its visible range of wavelength with the invisible wavelength of DNA, to make it visible under UV light.
Q.21. Why does DNA move towards the anode in gel electrophoresis? [HOTS]
Ans. The DNA fragments are negatively charged so they move towards the positively charged anode.
Q.22. Mention the type of host cells suitable for the gene guns to introduce an alien DNA.
Ans. Plant cells
Q.23. Which main technique and instrument is used to isolate DNA from any plant cell?
Ans. Centrifugation and centrifuge
Q.24. Why is it not possible for an alien DNA to become part of a chromosome anywhere along its length and replicate normally?
Ans. Alien DNA must be linked to ori or origin of replication site to start replication.
Q.25. Why is a thermostable DNA polymerase needed in amplification (genetic engineering)?
Ans. Because thermostable DNA polymerase remains active even at high temperature required for extension step of PCR.
Q.26. Suggest a technique to a researcher who needs to separate fragments of DNA.
Ans. Gel electrophoresis is used to separate DNA fragments.