Class 12th Biology 2017 Set1 Outside Delhi Board Paper Solution
Question 19
Describe the roles of heat, primers and the bacterium Thermus aquaticus in the process of PCR.
Answer
Role of Heat : It helps in denaturation or separation process in PCR. The ds DNA is heated in this process at very high temperature (95ºC) so that both the strands separates.
Role of primers : Primers are chemically synthesised small oligonucleotides of about 10-18 nucleotides that are complementary to a region of template DNA and helps in the extension of new chain.
Role of Bacterium Thermus aquaticus : From this bacterium, a thermostable DNA polymerase is isolated which can tolerate high temperatures and forms new strand.
Popular Questions of Class 12th biology
- Q:- What is spermatogenesis? Briefly describe the process of spermatogenesis.
- Q:- Why is reproduction essential for organisms? Answer
- Q:- Write a short note on
(a) Adaptations of desert plants and animals
(b) Adaptations of plants to water scarcity
(c) Behavioural adaptations in animals
(d) Importance of light to plants
(e) Effect of temperature or water scarcity and the adaptations of animals. - Q:- With a neat diagram explain the 7-celled, 8-nucleate nature of the female gametophyte.
- Q:- What is DNA fingerprinting? Mention its application.
- Q:- What is oogenesis? Give a brief account of oogenesis.
- Q:- Describe the structure of a seminiferous tubule.
- Q:- What is triple fusion? Where and how does it take place? Name the nuclei involved in triple fusion.
- Q:- With a neat, labelled diagram, describe the parts of a typical angiosperm ovule.
- Q:- Explain the Law of Dominance using a monohybrid cross.
Recently Viewed Questions of Class 12th biology
- Q:- Among the ecosystem services are control of floods and soil erosion. How is this achieved by the biotic components of the ecosystem?
- Q:- Draw a labeled diagram of female reproductive system.
- Q:- Offspring formed due to sexual reproduction have better chances of survival. Why? Is this statement always true?
- Q:- Find out what the various components of the medium used for propagation of explants in vitro are?
- Q:- If one can induce parthenocarpy through the application of growth substances, which fruits would you select to induce parthenocarpy and why?
- Q:- What is the ecological principle behind the biological control method of managing with pest insects?
- Q:- How is biodiversity important for ecosystem functioning?
- Q:- The species diversity of plants (22 per cent) is much less than that of animals (72 per cent). What could be the explanations to how animals achieved greater diversification?
- Q:- Can you think of a situation where we deliberately want to make a species extinct? How would you justify it?
- Q:- List any three important characteristics of a population and explain