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Hml 300: Genetic Disorders Question Paper
Hml 300: Genetic Disorders
Course:Bachelor Of Science In Medical Laboratory Science
Institution: Kenyatta University question papers
Exam Year:2010
INSTRUCTIONS
This Examination paper contains three sections:
1.
Section A:
Short Answer Questions
2.
Section B:
Essay Questions
3.
Section C:
Multiple Choice Questions
SECTION A:
Short Answer Questions:
Attempt ALL questions in this section (5 marks each)
Answers should be written on the provided booklet.
1.
Differentiate sex linked from sex limited traits.
2.
Explain dosage compensation in humans and its manifestation.
3.
Compare paracentric with pericentric inversions.
Page 1 of 9
SECTION B:
Essay Questions. Attempt ONLY ONE Question. (20 marks each)
Answers should be written in the provided booklet.
1.
Discuss variation in chromosome structure and associated syndromes.
2.
Discuss Y-linked and X-linked traits in humans giving appropriate examples.
SECTION C
There are thirty (30) Multiple Choice Questions (MCQ) in this section. Attempt ALL of
them by placing a circle around the letter representing the right answer. Each correct MCQ
answer is equal to half ( ½ ) a mark while a wrong answer attracts a minus quarter (- ¼)
of a mark. Total (15 marks)
1.
Which statement about human chromosomes is not correct?
a)
Sex is determined by sex chromosomes
b)
Males are homogametic
c)
A sperm has 22 autosomes and either X and Y chromosomes
d)
Presence of Y chromosome makes an individual male
e)
Y chromosome is usually smaller than X chromosome
2.
One of these statements incorrectly defines colour blindness
a)
Depends upon red, green and blue pigments
b)
Expressed in recessive condition
c)
Gene for normal vision is recessive over that of colour blindness
d)
A woman can be colour blind
e)
The gene can be transferred from a mother to a son.
3.
Which of these chemicals is not associated with albinism?
a)
Tyrosine
b)
Melamine
c)
Phenyalalamine
d)
Methiomine
Page 2 of 9
4.
In pedigree charts, a consanguineous marriage is represented by
a)
Two circles joined by an arrow
b)
Two squares opposite each other
c)
A square and a circle joined by a line
d)
A dark square and a dark circle joined by two lines
e)
A triangle joining a square and a circle
5.
Which statement concerning muscular dystrophy is incorrect.
a)
Affected Individual has muscular weakness
b)
Caused by absence of protein dystrophin
c)
There is excess calcium in the cells
d)
It is inherited in the same pattern as haemophilia
e)
There is excess blood released to the cells.
6.
Which statement is incorrect about sex-linked inheritance?
a)
Can only be recessively inherited
b)
Manifests in males in heterozygous state
c)
Transmission occurs through unaffected carrier females to their sons
d)
Male to male transmission is not possible
e)
Females manifest it if homozygous
7.
Which statement best defines autosomal recessive inheritance?
a)
Expression of defect is only in females
b)
Defect is not expressed if genes are heterozygous
c)
Genes can be expressed either in X or Y chromosomes
d)
No diseases follow this pattern of inheritance
e)
Inherited if unaffected carrier parent marries a normal partner.
Page 3 of 9
8.
Which statement about deletions is untrue?
a)
May be induced or spontaneous
b)
Can be terminal or interstitial
c)
Can revert to the normal
d)
Effect depends on the section that has been deleted
e)
Can lead to formation of acentric chromosomes
9.
One statement about Prader - Willi syndrome is correct:
a)
Caused by duplication
b)
Caused by partial deletion of long arm of chromosome 15
c)
Children have excessive suckling reflex in the early years
d)
Caused by partial deletion of short arm of chromosome 15
e)
Caused by deletion of chromosome 22
10.
A heterobrachial duplication is when the duplicated segment
a)
is displaced on a chromosome in a reversed order
b)
is adjacent to each other
c)
is displaced to a non-homologous chromosomes
d)
is displaced on a different arm within a chromosome
e)
Forms an extra chromosome
11.
What causes Wolf - Hirschorn syndrome?
a)
Deletion of short arm of chromosome 5
b)
Deletion of long arm of chromosome 4
c)
Duplication of a section of a chromosome
d)
Deletion of long arm of chromosome 5
e)
Deletion of long arm of chromosome 4
Page 4 of 9
12.
Which statement is incorrect about cri du chat syndrome?
a)
Caused by deletion of short arm of chromosome 5
b)
Caused by deletion of short arm of chromosome 22
c)
Children have moonlike faces and a flat nasal bridge
d)
Children are severely mentally retarded
e)
Patients reach adult age
13.
Which of these is not associated with a patient suffering from Pallister-Killian
syndrome?
a)
Mental retardation
b)
Flat nasal bridge
c)
Webbed neck
d)
Large mouth
e)
Small abnormal ears
14.
A non-reciprocal translocation
a)
Is unidirectional
b)
Does not interfere with the length of a chromosome
c)
Is not as common as reciprocal
d)
Occurs only on the same chromosome arm
e)
Interferes with gene order within a chromosome
15.
What chromosomes are usually involved in chronic Myelogenous leukemia?
a)
8 and 12
b)
4 and 5
c)
22 and 23
d)
9 and 22
e)
8 and 14
Page 5 of 9
16.
Which statement about Down''s syndrome is wrong?
a)
The centromere forms part of the inverted region
b)
Some sections are duplicated
c)
The exchange of segments produces unbalanced gametes
d)
Always produces unviable offsprings
e)
The wild type can be found in some gametes
17.
Which statement about Down''s syndrome is incorrect?
a)
Common among children born of older mothers
b)
Trisomy for chromosome 21
c)
Mental retardation and short body among patients
d)
Rare chromosomal abnormality
e)
Average survival age is 16 years
18.
One of the following is not characteristic of an XXY male:
a)
Average body height
b)
Abnormality of internal and external genitalia
c)
Bad facial expression
d)
Very low IQ
e)
Polydactyly on both hands
19.
Which statement about Alzheimer''s disease is incorrect?
a)
Harelip and cleft palate may occur
b)
Familial disease
c)
Common in old people
d)
Patients loose memory
e)
Caused by malfunction of chromosome 21
Page 6 of 9
20.
Which statement best describes mosaicism
a)
Tissues of organisms which look alike
b)
Tissues of organisms which look different
c)
Organisms that perform a common function
d)
Tissues within the same organism which are genetically different
e)
Tissues within the same organism which are genetically similar
21.
Which statement best describes epistatic gene action?
a)
Gene that affects several traits
b)
Gene that modifies the action of the other
c)
When a gene masks the effect of another
d)
When genes do the same function
e)
When a gene reinforces the work of the other
22.
A normal sequence of a certain human chromosome is 123*45678, where the star
represents the centromere. Give the correct name of the aberration if the order
mutated to 16543*278
a)
Pericentric inversion
b)
Interstitial deletion
c)
Paracentric inversion
d)
Intrachromosomal translocation
e)
Tandem duplication
23.
What is the basis of DNA finger printing?
a)
Use of chemicals to separate nucleotides
b)
Using identical blood types
c)
Appearance of unique nucleotide sequences in an individual
d)
Use of fingers to see print outs
e)
Use of unique enzymes
Page 7 of 9
24.
Which is the odd one out?
a)
Colour blindness
b)
Albinism
c)
Haemophilia
d)
Prader-Willi
e)
Phenylketunoria
25.
Which of the following is a sex-limited trait?
a)
Mid-digital hair
b)
Tongue rolling
c)
Window''s peak
d)
Milk production
e)
Polydactyly
26.
Which statement best describes penetrance?
a)
Percentage of individuals who are able to express a given genotype
b)
The degree of which a genotype is expressed
c)
The number of genes in an organism
d)
Occurrence of an event in a population
f)
Probability of expression of a given genotype
27.
A normal woman whose father was albino marries an albino man. What is the
probability that they have albino children?
a)
1/8
b)
1/4
c)
1/2
d)
1/3
e)
1/6
Page 8 of 9
28.
Which of these is an example of co-dominance?
a)
Albinism
b)
Muscular dystrophy
c)
A,B, O blood group
d)
Colour blindness
e)
Turner syndrome
29.
What is an antisense strand?
a)
A DNA strand that is transcribed to mRNA
b)
A DNA molecule that has no work
c)
A strand that destroys others
d)
Opposite strand
e)
A strand without a phosphate group
30.
A genetic counselor wants to trace the origin of a given disorder. Which is the most
appropriate method to use?
a)
Restriction Fragment Length Polymorphism
b)
Pedigree analysis
c)
PCR data
d)
DNA fingerprinting
e)
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