Class 12th Biology 2012 Set3 Delhi Board Paper Solution
Question 19
(a) Construct a complete transcription unit with promotor and terminator on the basis of the hypothetical template strand given below:
(b) Write the RNA strand transcribed from the above transcription unit along with its polarity.
OR
How are the structural genes inactivated in lac operon in E. Coli? Explain.
(a) Construct a complete transcription unit with promotor and terminator on the basis of the hypothetical template strand given below:
(b) Write the RNA strand transcribed from the above transcription unit along with its polarity.
OR
How are the structural genes inactivated in lac operon in E. Coli? Explain.
Answer
(a)
(b) RNA strand transcribed from above transcription unit.
(c) In the absence of lactose, no inactivation of repressor occurs and hence the repressor (which is constitutively produced from i gene) binds to the operator region of the operon; thus preventing RNA polymerase from transcribing the operon thus inactivating of the production of structural genes in E.coli occurs.
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:- Describe the structure of a seminiferous tubule.
- Q:- What is oogenesis? Give a brief account of oogenesis.
- 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:- What is pedigree analysis? Suggest how such an analysis, can be useful.
- Q:- Two heterozygous parents are crossed. If the two loci are linked what would be the distribution of phenotypic features in F1 generation for a dihybrid cross?
- Q:- Can you think of a situation where we deliberately want to make a species extinct? How would you justify it?
- Q:- Find out through internet and popular science articles whether animals other than man have self-consciousness.
- Q:- Depending upon the chemical nature of the template (DNA or RNA) and the nature of nucleic acids synthesised from it (DNA or RNA), list the types of nucleic acid polymerases.
- Q:- Explain the Law of Dominance using a monohybrid cross.
- Q:- In the medium where E. coli was growing, lactose was added, which induced the lac operon. Then, why does lac operon shut down some time after addition of lactose in the medium?
- Q:- Draw a labeled diagram of male reproductive system.
- Q:- What is triple fusion? Where and how does it take place? Name the nuclei involved in triple fusion.
- Q:- What is oogenesis? Give a brief account of oogenesis.