nnmlblh Ui'HVERSlTY DEPARTMENT OF NATURAL AND APPLIED SCIENCES COURSE CODE: GENSOZS PAPER: THEORY INSTRUCTIONS PWE J! PERMISSIBLE MATERIALS

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1 nnmlblh Ui'HVERSlTY OF SCIENCE nnd TECHNOLOGY FACULTY OF HEALTH AND APPLIED SCIENCES DEPARTMENT OF NATURAL AND APPLIED SCIENCES QUALIFICATION: BACHELOR OF SCIENCE (MAJOR AND MINOR) QUALIFICATION CODE: 07BOSC LEVEL: 6 COURSE NAME: GENETICS COURSE CODE: GENSOZS SESSION: JANUARY 2018 PAPER: THEORY DURATION: 3HOURS MARKS: 120 SUPPLEMENTARY/SECOND OPPORTUNITY EXAMINATION QUESTION PAPER EXAMINER(S) Prof Percy Chimwamurombe MODERATOR: Prof Sylvester Rodgers Moyo INSTRUCTIONS PWE J! Write clearly and neatly Number the answers clearly All written work MUST be done in blue or black ink No books, notes and other additional aids are allowed PERMISSIBLE MATERIALS Non- programmable Calculators THIS QUESTION PAPER CONSISTS OF 6 PAGES (Including this front page)

2 SECTION A: Multiple Choice Section [20 MARKS] A1. In Biotechnology, reporter genes are incorporated into vectors because they encode proteins that are readily detected. (1) chehsneedthem notchehneedthem A2. What is a shuttle vector? (1) is a cloning vector that can stably replicate in two different organisms veiflcle ashuflhngdevke noneoftheabove A3. lngenetherapmiuncfionalcowesofagenecanbesupphedtoan individual to treat human genetic diseases. (1) only for some diseases only for microbial diseases A4. The following are examples of transgenic plants (1) Bt- cotton Bt-maize Tomato flvr savr AHoftheabove A5. if two pa rents carry the recessive gene of Cystic Fibrosis, that is, they are heterozygous (C c), What is the probability that one child of the parents will suffer from the disease (1) )6 O lfi 34 A6. Genes show incomplete dominance when the heterozygous phenotype is (1) (C) fuzzy intermediate half way

3 A7. In codominance two alleles both affect phenotype in separate distinguishable ways (1) not always A8. What is epistasis? (1) a gene at one locus alters phenotypic expression of a gene when genes are silenced when gene are at the middle of the cell at another locus A9. Polygenic variation results in. (1) quantitative traits qualitative traits complex traits A10. If sex is determined by the X-Y system in humans, what system is used for chicken. (1) X-O system Z-W system Z~Y system haploid-diploid system A11. Which of the following define pleiotropism? (1) The action of two genes affects more than one trait (phenotype) The action of one gene affects more than one trait (phenotype) The action of three genes affects more than one trait (phenotype) all of the above A12. Pleiotropy and epistasis can be assumed to be the norm in biological systems (1) (3) since genes and their products operate within multiple networks operate in mutually interdependent networks. operate in both within the cell and between cells all of the above

4 A13. Phenocopy is phenotype arising from an environmental agent that mimics the effect of a mutant gene and it is (1) Not heritable Can be deleterious or beneficial can ignored (cl) a and b be are correct A14. Where do genetic variations come from? (1) (cl) mutations recombinations genetic drift all of the above A15. What is a genome? (1) a complete sets of genes of an organism a complete sets of genetics of an organism a complete sets of proteins of an organism a complete sets of DNA of an organism A16. The observable characteristics of an organism that result from the expression of genes is the organism s (1) phenotype. phenocopy genotype karyotype A17. A cross between homozygous purple-flowered and homozygous white-flowered pea plants result in offspring with purple flowers. This demonstrates (1). the blending model of genetics.. -breeding.. dominance.. a dihybrid cross. A18. What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants? (1) a) There is considerable genetic variation in garden peas. b) Traits are inherited in discrete units, and are not the results of "blending. c) Recessive genes occur more frequently in the F1 than do dominant ones. d) Genes are composed of DNA.

5 A19. What is the difference between a monohybrid cross and a dihybrid cross? (1) a) A monohybrid cross involves a single parent, whereas a dihybrid cross involves two parents. b) A monohybrid cross produces a single progeny, whereas a dihybrid cross produces two progeny. c) A dihybrid cross involves organisms that are heterozygous for two characters and a monohybrid only one. d) A monohybrid cross is performed for one generation, whereas a dihybrid cross is performed for two generations. A20. Human blood groups are an example of complete dominance. (1) it depends it depends on race on sex SECTION B [80 MARKS] 1. In guinea pig (Cavia), there are two alleles for colour, black and white and two alleles for hair length, short and long. In a breeding experiment all the F1 phenotypes produced from a cross between pure breeding, short -black haired and long white haired parents had short, black hair. Explain which alleles are dominant. (2) Explain the expected proportions of F2 phenotypes (8) 2. Explain using appropriate genetic symbols, the possible blood groups of children whose parents are both heterozygous, the father being blood group A and the mother B (5) If these parents have non-identical twins, what is the probability that both will have blood group A? (5) 3. In pepper plants, green (G) fruit color is dominant to red (g) and round (R) fruit shape is dominant to square (r) fruit shape. These two genes are located on different chromosomes.. What gamete types will be produced by a heterozygous green, round plant? (5). If two such heterozygous plants are crossed, what genotypes and phenotypes will be seen in the offspring and in what proportions? (5)

6 4. Hemophilia is a sex-linked trait where XH gives normal blood clotting and is dominant to the hemophilia allele X.. Give the genotypes of 1) a woman with normal blood clotting whose father had hemophilia and 2) a normal man whose father had hemophilia. (2). What is the probability that a mating between these two individuals will produce a child, regardless of sex, that has hemophilia? (4). If this couple has a daughter, what is the probability that the daughter a carrier of the hemophilia trait? What is the probability a daughter would have will be hemophilia? (2). If this couple has a son, what is the probability he will have hemophilia? (2) 5. Write the single letter abbreviation of the following peptide: -asn-lys-gln-arg-phe-trp-tyr-ile-leu-va - (10) 6. What is the role of the RNA polymerases in eukaryotes? (10) 7. Describe site-specific recombination in E. coli. (10) 8. Describe the three classes of transposons. (10) SECTION C [20 MARKS] 1. Describe in detail the various points at which gene expression regulated in eukaryotes from DNA to functional gene products. (20) can be END OF EXAMINATION QUESTIONS