Concepts in Genetics and Evolution — DU B. Sc. (Hons) Biochemistry Previous Year Question Papers

(iii) Allopatric and sympatric speciation (iv) Narrow and broad sense heritability (v) Generalized and Specialised transduction 2. There are 8 questions. 1. (a) Mention the term that best describes the following statements : (i) A gene present on Y chromosome responsible for a human embryo to develop as a male. (ii) An allele that causes death frequently at an early developmental stage, resulting in a missing genotype among the progeny. (iii) An autosomal trait expressed in one gender only. (iv) The appearance or manifestation of a character. (v) First individual being diagnosed with a trait/ disease shown in pedigree is denoted by a symbol. (vi) The test/tool used for analyzing genetic crosses in which one individual of unknown genotype is crossed with another individual with a homozygous recessive genotype for the trait in question. (c) State the Hardy Weinberg law. Calculate the allelic, genotypic and phenotypic frequencies in a ! population of 30,000 individuals in which 65 individuals are diagnosed positive for autosomal recessive disorder. (5,6,4) 7. Write short notes on the following: i (i) Penetrance and expressivity (ii) Genetic basis of flower development in (iii) Complementation test with an example (iv) Dosage compensation with a suitable example 8. Differentiate the following : (i) Maternal genetic effect and cytoplasmic inheritance (ii) Sex limited characteristic and sex influenced characteristic (iv) An allotetraploia formed from species I and species II (4,7,4) 6. (a) Elaborate on somatic-cell hybridization. A panel of cell lines was created from human-mouse somatic-cell fusions. Each line was examined for the presence of a human chromosome and for the production of a human protein. The following results were obtained: Human Human Chromosomes Cell Line Protein On the basis of these results, justi fy which human --chromosome carries the gene for protein. (b) Mention different types of chromosomal mutations and explain any one with the help of a diagram. What is the cause of Bar eye phenotype in Drosophila melanogaster? (vii) The phenomenon responsible for appearance of white-eyed females and red-eyed males in the F1 progeny of drosophila flies in a cross between a white-eyed female and a red-eyed male. (viii) One of the methods that determine the physical location of the genes on the chromosomes. (b) Define the following : (ii) Molecular markers (iv) LOD score (c) Give contribution of the following scientists : (i) Thomas Hunt Morgan 2. (a) In four Hfr strains of bacteria, all derived from an original Ft culture grown over several months, a group of hypothetical genes was studied and shown to be transferred in the order shown in the following table: Hfr Strain Order of Transfer (i) Assuming that F is the first gene along the chromosome, determine the sequence of all genes shown. Also show point of origin, and direction of gene transfer. (ii) One strain creates an apparent dilemma.