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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 ----—-