Sunday, March 10, 2019

Molecular basis of inheritance: Previous Year Questions Part 3

MOLECULAR BASIS OF INHERITANCE

2016 MARCH
1.     Result of a famous experiment is given in the figure. Answer the questions.
a.     Identify the experiment.
b.     Which property of the DNA is proved by this experiment?  (Scores: 2)
2.     Read carefully the sequence of codons in the mRNA unit and answer the questions.
a.     What change is needed in the first codon to start the translation process?
b.     If translation starts by that change, till which codon it can continues? Why?    (Scores: 2)
3.     Schematic representation of DNA fingerprints is shown below:
[Hints: C is a sample taken from a crime scene, A and B from suspected individuals]
a.     Which one of the suspected individual may involved in the crime?
b.     Write any other use of DNA fingerprinting. (2)
2016 SAY
1.     Observe the figure of mRNA and answer the questions:
a.     Find the start and stop codons. (Score 1)
b.     How many amino acids will be present in the protein translated from this mRNA?         (Score 1)
c.     The additional sequences that are not translated in mRNA are called ……….                                 (Score 1)
2.     a)  The hints of lac operon are given below:
Hints: Inducer, Repressor, Structural genes, Operator, Regulatory gene
1.   Which substance is acting as inducer in this operon?            (Score 1)
2.   Explain the working of operon in presence of the inducer.     (Scores 2)
OR
b)  With the help of the figure given, explain the processing of hnRNA to mRNA in eukaryotes.  (Scores 3)
2017 MARCH
1.     Which of the following combinations do not apply to DNA?
(a) Deoxyribose, Guanine               (b) Ribose, Adenine
(c) Deoxyribose, Uracil                    (d) Guanine, Thymine
(1)   (a) and (b)     (2)   (b) and (c)
(3)   (c) and (d)     (4)   (a) and (d)     (Score: 1)
2.     Examine the diagram of mRNA given below. Mark the 5’ and 3’ ends of the mRNA by giving reasons.  (Scores: 2)
3.     A small fragment of skin of a different person was extracted from the nails of a murdered person. This fragment of skin led the crime investigators to the murderer. Based on this incident answer the following questions:
(l) What technique was used by the investigators?
(2) What is the procedure involved in this technique?    (3)
OR
In an E. coli culture lactose is used as food instead of glucose. If so, answer the following questions:
(1) How do the bacteria respond to the above situation at genetic level?
(2) If lactose is removed from the medium what will happen?
2018 MARCH
1.     Expressed sequences in the gene are called
(a) Introns      (b) Mutons             (c) Exons               (d) Cistrons
2.     DNA is tightly packed structure and is found as units called nucleosomes.
(a) Explain the concept of nucleosomes.
(b) Differentiate between euchromatin and heterochromatin.
3.     Identify the disadvantages of RNA over DNA as a genetic material and explain it.
4.     (a) In lac Operon lactose act as inducer molecule. Evaluate the statement and explain it.
(b) Observe the diagram of lac Operon and identify labelled parts A, B, C and D.


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