LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034
B.Sc. DEGREE EXAMINATION – PLANT BIOLOGY & BIOTECHNOLOGY
|
FIFTH SEMESTER – NOV 2006
PB 5506 – GENETICS AND PLANT BREEDING
Date & Time : 01-11-2006/9.00-12.00 Dept. No. Max. : 100 Marks
Part A (20 marks)
Answer All questions
I Choose the Correct Answer ( 5 x 1 = 5 marks)
01.The nucleic acid was first isolated from the nuclei of pus cells by
- Freidrich Miesher b. W.T. Astbury
- Wilkins d. F.G. Banting
- The partial expression of both alleles in a heterozygote so that the phenotype is
intermediate between those of the two homozygotes is
- dominance b. incomplete dominance
- pleotropism d. independent assortment
- Genetic code determines
- constancy of morphological traits b. structural pattern of organism
- sequence of aminoacids in a protein sequence of nucleotides in a protein
- Which of the following represents Klinefelters syndrome ?
- XX b. XO c. XYY d. XXY
- Mutation was proposed as a theory for the operative mechanism of evolution by
- Charles Darwin b. Louis Pasteur
- Francisco Redi d. Hugo de Vries
II State whether the following statements are True or False ( 5 x 1 = 5 marks)
- Individuals with a dominant lethal gene die before they can reproduce.
- The sequence of nucleotide bases in the mRNA is complementary to the template
DNA strand.
- The regulatory gene of trp operon constitutively synthesizes a non- functional protein
called co- repressor.
- Down syndrome is the result of twenty first chromosome present in three doses.
- The cross between the parents belonging to two different species of the same genus
is called intraspecific hybridization.
III. Complete the following ( 5 x 1 = 5 marks)
- The condition in which one member of an allelic pair is manifested to the exclusion
of the other——————-.
12 ________ enzymes are capable of catalyzing phosphodiester bond formation.
13 The __________ gene marks the site at which transcription of mRNA starts.
14 The second correction system for correcting the occasional error missed by the
editing function is called _______ repair.
15 The use and disuse principle of evolution was proposed by _______.
- Answer all, each in about 50 words ( 5 x 1 = 5 marks)
- Define codominance.
- Distinguish between A DNA and Z DNA.
- What is poly A tail ?.
- Write the mode of action of alkylating agents.
- What is pureline selection ?.
PART B ( 5 x 8 = 40 marks)
Answer any five, each within 350 words only. Draw diagrams and flowcharts wherever necessary.
- What is quantitative inheritance? Briefly explain this with suitable example.
- Describe the structure and organization of a gene.
- Explain the structural organization of a chromosome.
- Write a brief note on the features of genetic code.
- Give a brief account on common defects in DNA and their origins.
- What is klinefelter’s syndrome ?. Add a note on its symptoms and related findings.
- Define mass selection. Briefly describe the procedure of mass selection and discuss
its merits and demerits.
- Give a brief account of Darwin’s theory of natural selection.
PART C ( 2 x 20 = 40 marks)
Answer the following, each within 1500 words only. Draw diagrams and flowcharts wherever necessary.
- (a) Write an essay on sex determination in plants.
OR
(b) i. Give an account of supercoiling of DNA.
- Discuss : ‘DNA is the genetic material’.
- (a) Describe the following with suitable examples.
- Genetic recombination using tetrad analysis.
- Transposable elements in plants.
OR
(b) Write an essay on different types of chromosomal aberrations.
Latest Govt Job & Exam Updates: