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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
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 allowedPWE‘J!‘PERMISSIBLE MATERIALS
Non- programmable Calculators
THIS QUESTION PAPER CONSISTS OF 6 PAGES
(Including this front page)
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)
(a) true
(b) false
(c) cheHsneedthem
(d) notcheHneedthem
A2. What is a shuttle vector? (1)
(a) is a cloning vector that can stably replicate in two different organisms
(b) veiflcle
(c) ashuflhngdevke
(d) noneoftheabove
A3. lngenetherapmiuncfionalcowesofagenecanbesupphedtoanindividual to treat human genetic diseases. (1)
(a) false
(b) true
(c) only for some diseases
(d) only for microbial diseases
A4. The following are examples of transgenic plants (1)
(a) Bt-—cotton
(b) Bt-maize
(c) Tomato flvr savr
(d) AHoftheabove
A5. if two pa rents carry the recessive gene of Cystic Fibrosis (c), that is, they are
heterozygous (C c), What is the probability that one child of the parents will suffer
from the disease (1)
(a) )6
(b) O
(c) lfi
(d) 34
A6. Genes show incomplete dominance when the heterozygous phenotype is (1)
(a)
(b)
(C)
(d)
fuzzy
intermediate
half way
none of the above
A7. In codominance two alleles both affect phenotype in separate
distinguishable ways (1)
(a) true
(b) false
(c) not always
(d) none of the above
A8. What is epistasis? (1)
(a) a gene at one locus alters phenotypic expression of a gene at another locus
(b) when genes are silenced
(c) when gene are at the middle of the cell
(d) none of the above
A9. Polygenic variation results in. (1)
(a) quantitative traits
(b) qualitative traits
(c) complex traits
(d) none of the above
A10. If sex is determined by the X-Y system in humans, what system
is used for chicken. (1)
(a) X-O system
(b) Z-W system
(c) Z~Y system
(d) haploid-diploid system
A11. Which of the following define pleiotropism? (1)
(a) The action of two genes affects more than one trait (phenotype)
(b) The action of one gene affects more than one trait (phenotype)
(c) The action of three genes affects more than one trait (phenotype)
(d) 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
(b) operate in mutually interdependent networks.
(c) operate in both within the cell and between cells
(d) all of the above
A13. Phenocopy is phenotype arising from an environmental agent that
mimics the effect of a mutant gene and it is (1)
(a) Not heritable
(b) Can be deleterious or beneficial
(c) can ignored
(cl) a and b be are correct
A14. Where do genetic variations come from? (1)
(a) mutations
(b) recombinations
(c) genetic drift
(cl) all of the above
A15. What is a genome? (1)
(a) a complete sets of genes of an organism
(b) a complete sets of genetics of an organism
(c) a complete sets of proteins of an organism
(d) 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)
(a) phenotype.
(b) phenocopy
(c) genotype
(d) karyotype
A17. A cross between homozygous purple-flowered and homozygous white-flowered
pea plants result in offspring with purple flowers. This demonstrates (1)
(a). the blending model of genetics.
(b). true-breeding.
(c). dominance.
(d). 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.
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 producestwo 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)
(a) false
(b) true
(c) it depends on race
(d) it depends 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.
(a)Explain which alleles are dominant. (2)
(b) Explain the expected proportions of F2 phenotypes (8)
2. (a) 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)
(b) 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.
(a). What gamete types will be produced by a heterozygous green, round plant? (5)
(b). If two such heterozygous plants are crossed, what genotypes and phenotypeswill be seen in the offspring and in what proportions? (5)
4. Hemophilia is a sex-linked trait where XH gives normal blood clotting and is
dominant to the hemophilia allele X“.
(a). 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)
(b). What is the probability that a mating between these two individuals will
produce a child, regardless of sex, that has hemophilia? (4)
(c). If this couple has a daughter, what is the probability that the daughter will be
a carrier of the hemophilia trait? What is the probability a daughter would have
hemophilia? (2)
(d). 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 can be
regulated in eukaryotes from DNA to functional gene products. (20)
--------END OF EXAMINATION QUESTIONS ----—-