Download Suppl Y1 Genetics 20.. - UR - College of Science and Technology

KIGALI INSTITUTE OF SCIENCE AND TECHNOLOGY
INSTITUT DES SCIENCES ET TECHNOLOGIE
Avenue de l'Armée, B.P. 3900 Kigali, Rwanda
INSTITUTE EXAMINATIONS - ACADEMIC YEAR 2012 - 2013
SUPPLEMENT EXAMINATION
FACULTY OF SCIENCE
SCIENCE 3: APPLIED BIOLOGY
FIRST YEAR SEMESTER II
BIO 3124- GENETICS
DATE: … /…/2013
TIME: 2 HOURS
MAXIMUM MARKS = 60
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INSTRUCTIONS:
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This examination paper contains two sections: A and B.
Section A is compulsory and choose any two questions in Section B
Do not bring any written material with you into the examination room.
Do not write any answer on this question Exam paper.
Do not forget to write your registration number on your answer booklet.
Write all your answers in the provided answer booklet.
Where appropriate draw large, clear and well labeled diagrams in your answers.
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SECTION A: Compulsory. Answer to all questions in this section, each question is 10 marks.
Total = 30 marks
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1. A) Distinguish between the following terms:
i) Genetics and Heredity
(2marks)
ii) Gene and Allele
(2marks)
iii) Dominant Trait and Recessive Trait
(2marks)
iv) Replication and Translation
(2marks)
v) Genotype and Phenotype
(2marks)
B) Explain the different Mendel`s laws? And give an example for each law.
(10 marks)
C) How many gametes will be produced for the following allele arrangements and indicate
these gametes for i and ii sub-questions:
a. AaBb
(3 marks)
b. AAEeDd
(3marks)
c. MmNnOoPPQQRrssTtQq
(4 marks)
SECTION B: Answer any two questions among the three in this section. Each question is 15
marks. Total = 30 marks
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2.
i) In Drosophila, the gene for white eyes and the gene that produces "hairy" wings have both
been mapped to the same chromosome and have a crossover frequency of 1.5%. A geneticist
doing some crosses involving these two mutant characteristics noticed that in a particular
stock of flies, these two genes assorted independently; that is they behaved as though they
were on different chromosomes. What explanation can you offer for this observation?
(5 marks)
ii) In the nematode Caenorhabditis elegans, dpy-5 and unc-4 are another set of recessive
alleles which confer the phenotypes of a dumpy body and uncoordinated movement,
respectively. A test cross is performed, and yields the following progeny shown below (on
the next page). Are the genes linked? If so, how many units apart are they on the
chromosome?
(5 marks)
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Phenotype
Dpy Unc
Wild Type
Unc
Dpy
#
Progeny
243
251
247
249
3. In mice, black color (B) is dominant to the white (b). at a different locus, a dominant allele
(A) produces a band of yellow just below the tip of each hair in mice with black fur. This
gives a frosted appearance known as agouti. Expression allele (a) results in a solid coat color.
If mice that are heterozygous at both loci are crossed.
a) What is the expected genotypic ratio of their offspring?
(6 marks)
b) What is the expected phenotypic ratio of their offspring?
(9marks)
4. Use the genetic code chart on the next page (page 4) to answer to this question.
The RNA sequence below encodes a very short protein:
5’ ACCGUACGACCAUGUCCCACUAUCCCUAGGCGAUC 3’
a) What is the codon where the protein synthesis will start? And what is the codon where
the translation will stop?
(3 marks)
b) What will be the sequence of amino acids in the protein?
(4 marks)
c) If the underlined base changed from U to G, what would be the effect on the protein?
What do we call this kind of mutation?
(4 marks)
d) If the underlined base changed from U to C, what would be the effect on the protein?
What do we call this kind of mutation?
(4 marks)
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END OF QUESTION PAPER
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