Fundamentals of Genetics — DU B.Sc. (Hons.) Zoology Previous Year Question Papers

1. (a) Define the following terms (any three) : (i) Frameshift mutation (ill) Penetrance (b) Give a suitable example for cach (any three): (i) Base Analogue (ii) Sex-influenced trait (iii) Lethal gene (c) Differentiate between the following (any three) : (i) Simple and Composite Transposons (ii) Silent mutation and Non-sense mutation (iii) Nuclear inheritance and extranuclear inheritance (iv) Monoecious and Dioecious organisms (d) Explain the following : (1) Distance in Linkage maps is expressed in map units, not in base pairs. (ii) Inversions are crossover suppressors. 2. (a) In Drosophila, the recessive mutant allele cinnabar (Ch) results in bright red eyes, curved (c) results in curved wings, and plexus (px) has extra wing veins. All three genes are linked. In a cross between on c px/ + + + females and cn c px / en c px males, following progeny were counted : (i) Deduce the order of genes. Phenotype (Genotype) Number cn c px 296 (ii) Determine the map distance and construct a linkage map. (I11) Calculate the coefficient of coincidence and interference. (2+4+2=8) (b) Discuss somatic cell hybridisation and the use of HAT medium. Explain its significance for gene 3. (a) What are non-allelic interactions? Explain any wthree modified Mendelian ratios. (10) (b) Explain how chromosomes carrying visible structural mutations were used to demonstrate the cytological basis of crossing over. (5) 4. (a) Give an account of various types of gene mutations. Discuss their effects with suitable examples. (10) (b) What is aneuploidy? Give one example each of monosomy and trisomy in humans, along with their karyotype abbreviations. (5) 5. (a) What is cytoplasmic inheritance? Classify cytoplasmic inheritance with examples. (10) (b) Write a note on Retrotransposons. (5) 6. Write short notes on any three of the following : (i) Dosage Compensation (ii) Transposable elements in Bacteria (iii) Polyploidy (iv) Polygenic Inheritance