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Sbt2254:General Genetics Question Paper

Sbt2254:General Genetics

Course:Bachelor Of Crop Protection

Institution: Meru University Of Science And Technology question papers

Exam Year:2013

QUESTION ONE (30 MARKS)
a) State any two (2) qualities that make an organism suitable for genetic experimentation. (2 Marks) b) Distinguish between i. Penetrance and expressivity ii. Linkage and crossing over iii. Genotype and phenotype (6 Marks) c) State any two (2) reasons as to why genetic mapping is important. (2 Marks) d) State the meaning of term polyploidy and outline any two (2) commercial applications of polyploidy in plants. (3 Marks) e) State the Hardy – Weinberg equilibrium theory and that the conditions a population must meet in order to maintain the Hardy – Weinberg equilibrium. (3 Marks) f) Name the syndrome associated with the following conditions and state the chromosome involved in each case. i. Trigomy – 13 ii. Trigomy – 18 iii. Trigomy – 21 (3 Marks)
g) Explain briefly three (3) ways in which variations can be introduced in a population through Meiosis. (3 Marks) h) In a survey of 1000 individuals, the following genotype distribution was reported. AA =353, Aa=494 and aa=153. Calculate the genotype and allele frequencies of this population. (3 Marks) i) State two (2) causes of inbreeding depression. (2 Marks)
2
j) State three (3) uses of inbreeding in qualitative genetics. (3 Marks)
QUESTION TWO (20 MARKS)
Describe in details any five (5) gene interactions and exceptions to mendelian inheritance.
QUESTION THREE (20 MARKS)
Construct a genetic map using the following data.
A line of drogophila has been constructed with three recessive mutations.

Vg=vestigial wings
The determinant of vergion (wild type) of each allele is vg+ or ec+, but will be written Parental homozygous recessive flies (sc ec vg/sc ec vg) were crogged with homozygous dominant type (wild type) (+++/+++). All the Fn flies produced had the dominant (wild type) phenotype. i.e
F1 were genotype (sc ec vg/+++)
F2 was produced by mating F1, flies with homozygous recessive flies (sc ec vg/sc ec vg). F2 generation with 6 different phenotype were produced:
Sc ec vg -417 (parental combination alleles)
+ + + -430 (parental combination alleles)
Sc + + - 25
+ ec vg -29
Sc ec + -44
+ + vg -37
Sc + vg -4
+ ec + -5
Total flies in F2:991
From this genetic data, determine the recombination frequencies between each pair of genes (i.e gc/ec ec/vg gc/vg). From recombination frequencies for each gene pair, construct a genetic map. Which are the rarest recombination phenotypes.

Sbt2254:General Genetics Question Paper

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