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Kwame Nkrumah University of Science and Technology Examination Details

Institution: Kwame Nkrumah University of Science and Technology, Kumasi
College: College of Science
Program: B.Sc. (Biological Sciences/Biochemistry)
Course Code: BIOL 153 Introductory Genetics
Year: First Year, First Semester 2021/2022
Exam Date: April 13, 2021
Exam Duration: 2 Hours
Instructions:
- Do not take any part of the question paper away from the examination hall.
- Serious consequences for non-compliance.
Answer Method: All questions to be answered on the scannable sheet provided.

Examination Questions

The theory that an embryo develops progressively from an undifferentiated cell is called:
a. Germplasm
b. Epigenesis
c. Pangenesis
d. Preformation
If a person with blood type AB were crossed with a person with blood type O, the offspring would be:
a. AB or O
b. AB only
c. A or B but not AB or O
d. None of the above
An individual organism whose chromosome number differs from the wild type by part of a chromosome set is a(an):
a. Euploid
b. Duploid
c. Aneuploid
d. Haploid
In pedigree analysis:
a. Double horizontal lines denote consanguineous marriage
b. An affected child is shown with an arrow
c. Probabilities are used to determine genotypes of deceased children
d. Any person marrying into a family is assumed homozygous recessive for the gene in question
The correct model of DNA structure was elucidated by:
a. Linus Pauling
b. Hershey and Chase
c. Erwin Chargaff
d. Watson and Crick
Which of these DNA fragments will have a higher melting temperature?
a. GCATTGACCGGAGGGACT vs CGTAACTGGCCTCCCTGA
b. GGATTTCAATTACTTAAT vs CCTAAAGTTAATGAATTA
A red flowered plant crossed with a white flowered plant results in pink plants showing incomplete dominance. The expected fraction of pink plants in the F1 generation would be:
a. 0.25%
b. 50%
c. 75%
d. 100%
A pictorial representation of an individual's collection of chromosomes is called:
a. Amniocentesis
b. Staining
c. Prototype
d. Karyotype
What can you infer about an organism with a base composition of:
A (adenine) = 23%; T (thymine) = 24%; G (guanine) = 17%; C (cytosine) = 16%
a. Single-stranded DNA
b. Double-stranded RNA
c. Collinearity between pyrimidines and purines
d. None of the above is compatible with the evidence.
During DNA replication, the enzyme DNA ligase:
a. Connects short segments of DNA together
b. Connects the first few nucleotides of each new molecule
c. Opens the helix at the replication fork
d. Removes the "over winding" caused by the opening of the DNA helix.
Alleles on the same chromosome that are usually inherited together are said to be:
a. Functional
b. Synthetic
c. Recombinant
d. Linked
An inversion including the centromere is called pericentric; one not involving the centromere is called paracentric. Which of the following would be considered an inversion?
a. FEFCDAB
b. ABEDCFG
c. ABCEFGD
d. FGCBADE
Which of the following has very few consequences but sometimes causes sterility, menstrual irregularity, or mild mental retardation?
a. 45,X (Turner syndrome)
b. XXY (Klinefelter syndrome)
c. XXX (Trisomy X)
d. Trisomy 21
Which of the following is characterized by a broad "webbed neck," reduced stature, and ankle/wrist swelling?
a. 45,X (Turner syndrome)
b. XXY (Klinefelter syndrome)
c. XXX (Trisomy X)
d. Trisomy 21
Which of the following would you expect to have the longest survival time?
a. Trisomy 13 (Patau syndrome)
b. Trisomy 18 (Edward syndrome)
c. Trisomy 21 (Down syndrome)
d. Trisomy 11 (Patrick syndrome)
How many chromosomes are there in human tetraploidy?
a. 24
b. 47
c. 69
d. 92
Which of the following properties are NOT accepted in the Watson and Crick model for DNA structure?
a. Nucleotides connected by phosphodiester bonds
b. The two strands are complementary
c. Adenine pairs with cytosine
d. The two strands are antiparallel.
A man with an X-linked disease mates with a unaffected female. If they have four sons, how many will have the disease?
a. 3
b. 2
c. 1
d. 0
Which of the following synthesizes a DNA strand complementary to an RNA strand?
a. DNA ligase
b. DNA polymerase
c. Reverse transcriptase
d. Restriction endonuclease
Sister chromatids attach to the centromere during which phase of mitosis?
a. Prophase
b. Metaphase
c. Anaphase
d. Telophase
How many autosomes exist in humans?
a. 22
b. 23
c. 44
d. 46
The process of DNA replication is said to be semi-conservative, meaning:
a. Only half of the DNA is passed on, the remainder is discarded as heterochromatin.
b. RNA replaces some of the DNA during replication.
c. Base-pairing rules change each purine position to a pyrimidine, and vice versa during replication.
d. Each daughter duplex has one parental duplex strand.
In the sex determination of most birds, moths, and some fishes, the females are:
a. Homogametic, heterogametic
b. Heterogametic, homogametic
c. Heterogametic, hemizygous
d. Hemizygous, heterogametic
How many different genotypes can exist in a population with the dominance hierarchy g> gb> ge> gd> ge> g> gh?
a. 16
b. 18
c. 22
d. 28
In the chi-square test, the p-value refers to:
a. The chance that the results could have been caused by a true null hypothesis
b. The chance that the results could have been caused by a false null hypothesis
c. The chance that results could have been caused by a true alternative hypothesis.
d. The null hypothesis should be accepted
If cells undergo mitosis without cytokinesis, this results in:
a. A cell with a single large nucleus
b. A cell with two nuclei
c. Cells with abnormally small nuclei
d. Death of a cell line
What is the correct definition of a dominant allele?
a. Expressed only in a heterozygous condition
b. Expressed only in a homozygous condition
c. A recessive allele expressed in a homozygous condition
d. A dominant allele is more likely to be passed to future generations than a recessive allele
Crossing two true-breeding strains of corn results in purple kernels with a subsequent F2 ratio of 9 purple to 7 white. This is likely an example of:
a. Incomplete dominance
b. Blending
c. Codominance
d. Epistasis
The closer genes are to each other, the:
a. Less likely they are to undergo recombination
b. Less likely they are to be linked
c. More likely they are to undergo recombination
d. More likely they are to be linked
The two strands of a DNA molecule are held together by:
a. Phosphodiester bonds
b. Ionic bonds between the phosphates
c. Hydrophobic interactions between the bases
d. Hydrogen bonds
Which genetic disorder results in taller than average males with possible aggressive behavior?
a. 45,X (Turner syndrome)
b. XXY (Klinefelter syndrome)
c. XXX (Trisomy X)
d. 47, XYY syndrome
Which is the most common type of inherited X-linked color blindness?
a. Red and green
b. Red and blue
c. Blue and yellow
d. Blue and green
An allele at one locus affecting several phenotypic traits is an example of:
a. Codominance
b. Incomplete dominance
c. Epistasis
d. Pleiotropic gene effect
The stages of prophase I in order are:
a. Zygonema, leptonema, diakinesis, pachynema, diplonema
b. Leptonema, zygonema, pachynema, diplonema, diakinesis
c. Diakinesis, diplonema, zygonema, pachynema, leptonema
d. Zygonema, leptonema, pachynema, diakinesis, diplonema
The expression of human blood groups illustrates:
a. Epistasis
b. Pleiotropism
c. Incomplete dominance
d. Codominance
All of the following are true about telomeres EXCEPT:
a. Non-coding regions at the tips of chromosomes
b. Composed of repeating sequences of TTAGGG
c. Increased longevity with every division
d. Decreased longevity with every division
A human gene is said to be sex-linked if:
a. More common in females
b. Found on the Y chromosome
c. Found on the X chromosome
d. Expressed only in males
In a pedigree, an affected male is represented by:
a. Half-shaded square
b. Non-shaded square
c. Fully-shaded square
d. Half-shaded circle
A child diagnosed with a rare genetic disease from consanguineous parents, with a grandparent having the same disorder, follows:
a. X-linked dominant
b. X-linked recessive
c. Autosomal dominant
d. Autosomal recessive
Probability that an unaffected sister of a cystic fibrosis child is a carrier is:
a. 1/3
b. 1/4
c. 1/2
d. 2/3
Only found in meiosis:
a. Spindle formation
b. Chromosome condensation
c. Chromosome movement to poles
d. Synapsis
If a father and son both have postaxial polydactyly, the pattern of inheritance is likely:
a. X-linked recessive
b. Autosomal dominant
c. Autosomal recessive
d. Y-linked
The probability of all children being either boys or girls is:
a. 1/4
b. 1/6
c. 1/8
d. 1/10
First to obtain X-ray diffraction data of DNA showing it as a helix:
a. Watson and Crick
b. Erwin Chargaff
c. Rosalind Franklin
d. P. A. Levine
At birth, oocytes are suspended in which phase of meiosis?
a. Prophase I
b. Metaphase I
c. Anaphase I
d. Metaphase II
What does bivalent of homologous chromosomes mean in meiosis?
a. Two chromosomes in the unit
b. Four chromosomes in the unit
c. Two chromatids in the unit
d. Four chromatids in the unit
What does tetrad of homologous chromosomes mean in meiosis?
a. Two chromosomes in the unit
b. Four chromosomes in the unit
c. Two chromatids in the unit
d. Four chromatids in the unit
Master gene for male sex determination is named:
a. SRY
b. MSG
c. DNA
d. RNA
A girl resembles her father more than her mother implies:
a. Identical karyotype as father
b. Most genes inherited from the father are sex-linked
c. Sex chromosomes transmitted from the mother have few or no genes
d. Dominant genes inherited from the father
Syndrome associated with the chromosome complement of 47, XXY is:
a. Prader Willi syndrome
b. Angelman syndrome
c. Klinefelter syndrome
d. Turner syndrome
Expected outcome of a cross between two heterozygous tall plants is:
a. 76 tall: 23 short
b. 24 tall: 49 medium: 25 short
c. 53 tall: 147 short
d. All tall
Blood transfusion compatibility involves:
a. Agglutination reaction
b. Histocompatibility test
c. Cross matching
d. Karyotyping
In an area with malaria, the parents had children with the following genotypes: ss, Ss, SS, ss, Ss, Ss, and SS. The parental genotypes must be:
a. ss x SS
b. SS x SS
c. Ss x Ss
d. Ss x ss
Which is not a common method in human genetic analysis?
a. Test cross
b. Karyotyping
c. RFLP analysis
d. Pedigree analysis
Why is it predicted that half of human babies are male and half female?
a. Due to segregation of X and Y chromosomes during male meiosis
b. Due to segregation of X chromosomes during female meiosis
c. All eggs contain an X chromosome
d. One-half of all eggs produce females
A human male with an allele on the X chromosome is described as:
a. Homozygous
b. Hemizygous
c. Monozygous
d. Holozygous
Diagnosis of chromosomal aneuploidy is done via a combination of amniocentesis, cell culture, and:
a. RFLP analysis
b. Pedigree analysis
c. Karyotyping
d. Somatic cell fusion
The terminal glycoprotein of the A antigen is _ while that of the B antigen is:
a. Fructosamine and glucosamine
b. Galactosamine and glucose
c. Galactosamine and galactose
d. Galactose and galactosamine
Hemophilia is an X-linked recessive disorder. If an unaffected father mates with an affected mother, what is the probability all children will be affected?
a. 1/2
b. 1/4
c. 1/6
d. 1/8
Using a Punnett square, the genotype probabilities for a homozygous dominant mother and heterozygous father are:
a. 100% homozygous dominant; 0% heterozygous; 0% homozygous recessive
b. 50% homozygous dominant; 50% heterozygous; 0% homozygous recessive
c. 25% homozygous dominant; 50% heterozygous; 25% homozygous recessive
d. 0% homozygous dominant; 25% heterozygous; 75% homozygous recessive
According to Mendel's principle of independent assortment, the following alleles (pea characteristics) would be transmitted together if on different loci?
a. Wrinkled and short
b. Round and tall
c. Wrinkled and tall
d. None are transmitted together
Mendel's principle of segregation states:
a. Paired genes are transmitted together and hereditary factors are blended
b. One member of a paired gene is transmitted, hereditary factors are blended
c. Paired genes are transmitted, and hereditary factors are not blended
d. One member of a paired gene is transmitted, hereditary factors are not blended
Regarding the ABO blood system:
a. A antigen individuals do not produce anti-A antibody
b. Type AB normally produces anti-A and anti-B antibodies
c. Only type O does not have A or B antigens
d. B antigen individuals produce anti-B antibody
An individual's ABO blood type is determined by:
a. Genetic inheritance and environmental influences during life
b. Environmental influences alone
c. The inheritance of 1 of 3 possible alleles (A, B, or O) from each parent
d. The inheritance of 1 of 3 alleles and environmental factors
If one parent is blood type A and the other is B, possible blood types for the offspring are:
a. A
b. O
c. AB
d. Any of the above
Male sex chromosome abnormalities may stem from abnormal numbers of which chromosome?
a. The X
b. The Y
c. Either the X or the Y
d. None of the above
A human female with karyotype XO will:
a. Have Klinefelter Syndrome
b. Have Turner syndrome
c. Be normal since the second X isn't used
d. Have Down syndrome
The ABO blood group system is controlled by:
a. Four and eight phenotypes
b. Four and three phenotypes
c. Eight and four phenotypes
d. Three and four phenotypes
Codominance is where:
a. One allele's expression is suppressed
b. Both alleles contribute to the phenotype of the heterozygote
c. Both alleles express equally
d. The heterozygote has a completely different phenotype from both homozygotes
Most Down syndrome cases result from:
a. Non-disjunction during maternal meiosis
b. Mosaicism of normal and trisomic cell lines
c. Unbalanced translocations
d. End-to-end fusion of two chromosomes 21
A variant form of a gene that produces a different product is called:
a. Gene
b. Allele
c. Locus
d. Genotype
The central dogma of molecular biology states that:
a. DNA directs the making of RNA, which directs protein synthesis
b. A T and G = C
c. Three types of RNA are involved in protein synthesis
d. Primary sites of protein synthesis are nucleus and ribosomes.
In a determined pedigree, affected individuals are represented by filled symbols. This pattern of inheritance can be described as:
a. Autosomal dominant
b. Autosomal recessive
c. Sex-linked dominant
d. Sex-linked recessive
Variation in male heights without obvious phenotypes is an example of:
a. Continuous variation
b. Epistasis
c. Pleiotropism
d. Independent assortment
A couple has a child with Tay Sachs disease and three unaffected children. The most likely genetic explanation is:
a. Autosomal dominant disease
b. Autosomal recessive
c. Sex-linked recessive
d. Cannot make a reasonable guess
Mendel chose true breeding cultivars of the pea plant for an experiment, resulting in:
a. Parental (P) generation
b. First filial (F1) generation
c. Second filial (F2) generation
d. Hybrids
Individuals with type O blood are universal donors because:
a. Their RBCs lack antibodies A and B
b. Their RBCs have antibodies A and B
c. Their RBCs lack antigens A and B
d. Their RBCs have antigens A and B
Which statement about Down syndrome is false?
a. Frequency increases dramatically in mothers over 40
b. Cause is non-disjunction during first meiotic division
c. Affected individuals have two extra autosomes
d. Long-time lag in meiosis onset and completion increases incidence in older mothers
Hemophilia, a genetic disease in royal houses of Europe, implies that:
a. At least one sister was a carrier
b. All four sisters were carriers
c. At least one sister had hemophilia like Alexis
d. Alexis inherited the gene from Nicholas II
Red-green color blindness is sex-linked and recessive (e). A normal vision man marries a color blind woman, resulting in a color blind daughter. This tells us that:
a. The woman is Ee
b. The daughter is eY
c. The man probably is not the child’s father
d. Color blindness is not a genetic trait
A man carrying a harmful sex-linked gene passes it to:
a. All of his daughters
b. Half of his daughters
c. Half of his sons
d. All of his sons
Recessive allele on the X chromosome causes color blindness. A non-color blind woman with a color blind father marries a color blind man. Chance their son will be color blind is:
a. 0%
b. 25%
c. 50%
d. 100%
Traits controlled by sex-linked recessive genes are more often expressed in males because:
a. Males inherit these genes from fathers
b. Males are always homozygous for these genes
c. All male offspring of a carrier get the gene
d. The male has only one gene for the trait
An organism heterozygous for four pairs of genes produces how many genetically distinct gametes?
a. 4
b. 16
c. 24
d. 64
In guinea pigs, black hair (B) is dominant to brown (b), and short hair (S) is dominant to long (s). Crossing BBSS with bbss yields a testcross phenotypic ratio of:
a. 1:1
b. 3:1
c. 9:3:3:1
d. 1:1:1:1
To determine if yellow-seeded pea plants are homozygous or heterozygous, cross with:
a. True breeding yellow-seeded plants
b. True breeding green-seeded plants
c. Heterozygous green-seeded plants
d. Heterozygous yellow-seeded plants
Results of a testcross revealing all offspring resembling the parent tested indicates:
a. Heterozygous
b. Recessive
c. Self-pollinated
d. Homozygous
Mendel's law of segregation states:
a. Paired alleles move apart during gamete formation
b. Each gamete receives a full chromosome complement
c. Alternative gene forms exist
d. Genes end up in gametes by chance
If 20% of nucleotides in double-stranded DNA are G, the percentages of A, C, and T are respectively:
a. 20, 20, 40
b. 20, 30, 40
c. 30, 20, 30
d. 30, 30, 40
A cross resulting in 915 offspring with normal pigmentation and 310 with albinism concludes that:
a. One parent was homozygous for albinism
b. Both parents were heterozygous
c. One parent was homozygous for normal pigmentation
d. Both parents were albinos
Which statement is false?
a. Same phenotype individuals may have different genotypes
b. Dominant phenotype mating can't produce recessive phenotype offspring
c. Recessive phenotype mating usually does not produce dominant phenotype offspring
d. Same genotype individuals might have different phenotypes
Which is not a source of variety in sexually reproducing species?
a. Crossing over
b. DNA replication
c. Distribution of chromosomes in gametes
d. Independent assortment of chromosomes during meiosis I
Which statement is false?
a. DNA mutations are the ultimate source of genetic variability
b. The effects of a mutation depend on the mutation nature, organism, and environment
c. Genetic exchange does not combine useful mutations
d. Eukaryotic organisms use meiosis for genetic exchange between individuals.
Hydrogen bonds can form between guanine and cytosine; while _ bonds form between adenine and thymine:
a. 2
b. 3
c. 4
d. 5
The earliest event of meiosis is:
a. Chromosomes move to the spindle equator
b. Chromatids separate and migrate to opposite poles
c. Crossing over occurs
d. Homologous chromosomes pair along their lengths
Reciprocal exchange of genetic materials between similar chromosomes is termed:
a. Crossing over
b. Segregation
c. Synapsis
d. Translocation

Blood Type and Genetics

A woman of blood group A, Rh positive has a daughter with O positive:
- Possible genotypes:
1. Father's possible genotype: a. Pr, b. PPRR, c. PIR, d. Pirr
2. Mother's possible genotype: a. PPRR, b. PPR, c. Pirr, d. PIR
3. Father's possible phenotype: a. O negative, b. B positive, c. A positive, d. O positive

Cell Cycle and Mitosis

Understanding cytokinesis without proper microtubule polymerization leads to:
1. a. Complete cell cycle yielding one tetraploid cell
2. b. Daughter cells having the same number of chromosomes as the parent before division

Sequence Explanation

For the DNA sequence GCCTAT, the complementary nucleotide sequence is:
1. a. CGGATA