List of top Questions asked in CBSE CLASS XII

What does the term 'fed' in fed-batch culture refer to?
Describe the Blue-White selection method of screening for the presence of recombinant plasmids.
Briefly describe Nick Translation technique.
How can you differentiate between cancerous and non-cancerous cells in culture by microscopic examination? Give one example of each of such cell types.
Name the genes which fuse during translocation in Philadelphia chromosome.
During FISH technique, is any fluorescence detected in the der 9 chromosome? Why?
Enlist any two limitations of batch culture.
How is CML detected by FISH techniques?
Since many centuries, whey has been used for the treatment of numerous ailments. Briefly elaborate upon the scientific relevance of it.
Explain briefly the procedures of the following techniques used in recombinant DNA Technology:
(i) Transfection
(ii) Electroporation
(iii) Biolistics
What is the use of introducing the property of delayed fruit ripening in some plants? Explain the methods used for delaying fruit ripening.
Briefly explain the process of sickling of Red Blood Cells (RBCs) during sickle cell anaemia. Why does sickle celled RBCs lead to anaemic conditions in patients?
Selection methods are based on the expression or non-expression of certain traits in recombinant microbial cells. Enlist such any three traits.
How does the metagenomics approach helps to identify novel genes present in an environment? Explain the process.
Mention the catalytic triad (along with diagram) which contributes to the enzymatic activity of native subtilisin. Why was this enzyme improved by protein engineering? Write the method used in this process.
Even if we know where the genes are present in a genome, it is not entirely clear how to count them. Give two reasons for this problem.
Although not required for cell growth, antibiotics are one of the most essential components of animal cell culture medium. Why? Give examples of two such antibiotics often used in animal cell culture medium.
Given below is a single stranded sequence of DNA:
5' ACTAGAATTCGCCA 3'
Which restriction enzyme would cleave this sequence in double stranded form? Illustrate the fragments that will be generated upon digestion by this restriction enzyme.
What is meant by 'Gene knock out'? How is it useful in developing mouse models for studying human diseases?
On which plasmid are Bacterial Artificial Chromosome (BAC) vectors based? Enlist the important sequences present in these vectors.
How is chymotrypsinogen converted to chymotrypsin in the duodenum? What is the name of this process?
Why is an inverted microscope required to observe animal cell cultures?
SCID (Severe Combined Immuno Deficiency) is caused due to deficiency of which enzyme?
Assertion (A): The human embryonic stem cells can be derived from the inner cell mass of blastocyst and cultured in a suitable nutrient medium.
Reason (R): It is possible to selectively remove a gene and make precise genetic modification in mouse embryonic stem cells.
Assertion (A): The gene that encodes for Barnase is used to induce male sterility in transgenic plants.
Reason (R): Barnase is a RNA hydrolyzing enzyme that inhibits pollen formation in the tapetal cells of anther.