EXAM 1

Question 1

According to Mendel’s laws, if a homozygous dominant individual (RR) is crossed with a homozygous recessive individual (rr) for a single trait, what will be the genotype of all individuals in the F1 generation?
a) RR
b) rr
c) Rr
d) RR and rr equally

Answer 1

c) Rr

The law of dominance states that in a cross between true-breeding parents with contrasting traits, all offspring will be heterozygous and express only the dominant trait

Question 2

Which of the following is an example of an autosomal recessive inheritance pattern?
a) Huntington’s disease
b) Achondroplasia
c) Cystic fibrosis
d) Free hanging earlobes

Answer 2

c) Cystic fibrosis

Autosomal recessive inheritance requires two copies of the recessive gene for the trait to be expressed. Huntington’s disease and achondroplasia are autosomal dominant, and free hanging earlobes are a dominant trait

Question 3

A pedigree analysis shows that a certain trait appears in every generation, and affected individuals all have at least one affected parent. This pattern is most consistent with:
a) Autosomal recessive inheritance
b) X-linked recessive inheritance
c) Autosomal dominant inheritance
d) Mitochondrial inheritance

Answer 3

c) Autosomal dominant inheritance

Dominant traits typically appear in each generation, and affected individuals usually have an affected parent in autosomal dominant inheritance

Question 4

What is the term for the phenomenon where a heterozygous individual expresses an intermediate phenotype compared to the two homozygous phenotypes?
a) Codominance
b) Complete dominance
c) Incomplete dominance
d) Polygenic inheritance

Answer 4

c) Incomplete dominance

Intermediate expression, also known as incomplete dominance, results in a heterozygous phenotype that is a blend of the two homozygous phenotypes

Question 5

Blood type AB in humans is an example of:
a) Complete dominance
b) Incomplete dominance
c) Codominance
d) Sex-linked inheritance

Answer 5

c) Codominance

In codominance, both alleles are expressed in the heterozygous individual. In blood type AB, both the IA and IB alleles are expressed

Question 6

The percentage of individuals with a particular genotype who actually display the expected phenotype is known as:
a) Expressivity
b) Penetrance
c) Pleiotropy
d) Epistasis

Answer 6

b) Penetrance

Penetrance refers to the proportion of individuals with a specific genotype that exhibit the corresponding phenotype

Question 7

Which of the following describes a reciprocal translocation?
a) Loss of a segment of a chromosome
b) Duplication of a segment within a chromosome
c) Exchange of segments between nonhomologous chromosomes
d) Inversion of a segment within a chromosome

Answer 7

c) Exchange of segments between nonhomologous chromosomes

A reciprocal translocation involves a two-way exchange of segments between two nonhomologous chromosomes

Question 8

Down syndrome is most commonly the result of which type of chromosomal abnormality?
a) Monosomy
b) Trisomy
c) Deletion
d) Translocation

Answer 8

b) Trisomy

Down syndrome typically results from trisomy 21, meaning there are three copies of chromosome 21 instead of the usual two

Question 9

What is the karyotype of a female with Turner syndrome?
a) 45, XXY
b) 45, X
c) 45, XXX
d) 45, XY

Answer 9

b) 45, X

Turner syndrome in females is characterized by the presence of only one X chromosome, resulting in a 45, X karyotype

Question 10

Fluorescence in situ hybridization (FISH) is a molecular cytogenetic technique that uses:
a) Antibodies to detect specific proteins on chromosomes
b) Radioactive isotopes to label DNA sequences
c) Fluorescently labeled DNA probes to target specific DNA or RNA sequences
d) Enzymes to cut DNA at specific restriction sites

Answer 10

c) Fluorescently labeled DNA probes to target specific DNA or RNA sequences

FISH utilizes DNA probes labeled with different colored fluorescent tags to visualize specific regions of the genome

Question 11

What is the fundamental repeating unit of chromatin in eukaryotes?
a) Histone
b) Nucleosome
c) Solenoid
d) Chromatosome

Answer 11

b) Nucleosome

The nucleosome, consisting of histone proteins and wrapped DNA, is the basic structural and functional unit of chromatin

Question 12

Which of the following nitrogenous bases is found in RNA but not in DNA?
a) Adenine
b) Guanine
c) Cytosine
d) Uracil

Answer 12

d) Uracil

RNA contains uracil as one of its pyrimidine bases, while DNA contains thymine instead

Question 13

What type of bond connects the nucleotides in a single strand of DNA?
a) Hydrogen bond
b) Ionic bond
c) Peptide bond
d) Phosphodiester bond

Answer 13

d) Phosphodiester bond

A phosphodiester bond links the 5’ phosphate group of one nucleotide to the 3’ hydroxyl group of the next, forming the DNA backbone

Question 14

According to Chargaff’s rules, in a double-stranded DNA molecule:
a) [A] = [G] and [C] = [T]
b) [A] = [T] and [C] = [G]
c) [A] = [C] and [T] = [G]
d) [A] + [T] = [G] + [C]

Answer 14

b) [A] = [T] and [C] = [G]

Chargaff observed that the amount of adenine is equal to the amount of thymine, and the amount of cytosine is equal to the amount of guanine in DNA

Question 15

The semi-conservative model of DNA replication suggests that each new DNA molecule consists of:
a) Two newly synthesized strands
b) Two parental strands
c) One parental strand and one newly synthesized strand
d) Fragments of parental and newly synthesized strands

Answer 15

c) One parental strand and one newly synthesized strand

In semi-conservative replication, each daughter DNA molecule inherits one original parental strand and one newly synthesized complementary strand

Question 16

Which enzyme is responsible for unwinding the double-stranded DNA at the replication fork in prokaryotes?
a) DNA polymerase
b) DNA ligase
c) Helicase
d) Primase

Answer 16

c) Helicase

Helicase unwinds the DNA double helix at the origin of replication, creating two replication forks

Question 17

Okazaki fragments are synthesized on the:
a) Leading strand in the 5’ to 3’ direction
b) Leading strand in the 3’ to 5’ direction
c) Lagging strand in the 5’ to 3’ direction
d) Lagging strand in the 3’ to 5’ direction

Answer 17

c) Lagging strand in the 5’ to 3’ direction

Due to the 5’ to 3’ directionality of DNA polymerase, the lagging strand is synthesized discontinuously in short fragments called Okazaki fragments, each synthesized in the 5’ to 3’ direction away from the replication fork

Question 18

Telomeres are repetitive nucleotide sequences found at the:
a) Centromeres of chromosomes
b) Origins of replication
c) Ends of chromosomes
d) Spindle fibre attachment sites

Answer 18

c) Ends of chromosomes

Telomeres are located at the ends of chromosomes and consist of repetitive DNA sequences

Question 19

Which DNA repair mechanism directly reverses pyrimidine dimers formed by UV radiation in some organisms?
a) Base excision repair
b) Nucleotide excision repair
c) DNA photolyase
d) Mismatch repair

Answer 19

c) DNA photolyase

DNA photolyase uses light energy to break the covalent bonds in pyrimidine dimers, directly restoring the original bases

Question 20

The Human Genome Project aimed to:
a) Identify all proteins in the human body
b) Determine the complete DNA sequence of the human genome
c) Develop new gene therapy techniques
d) Understand the function of all human genes

Answer 20

b) Determine the complete DNA sequence of the human genome

A primary goal of the Human Genome Project was to determine the sequence of the approximately 3 billion base pairs that make up human DNA

Question 21

Which of the following best describes a gene in the context of genomics?
a) The sum total of all an individual organism’s DNA
b) A segment of DNA that codes for a protein only
c) A segment of DNA that contains biological information, including sequences for proteins and functional RNAs
d) A non-coding region of the genome with regulatory functions

Answer 21

c) A segment of DNA that contains biological information, including sequences for proteins and functional RNAs

Genes are parts of the genome that contain biological information, which includes coding sequences for proteins as well as sequences for various functional RNAs

Question 22

Interspersed repeats and tandem repeats are two main types of:
a) Protein-coding genes
b) Regulatory DNA sequences
c) Repetitive DNA
d) Single nucleotide polymorphisms

Answer 22

c) Repetitive DNA

The human genome contains a significant amount of repetitive DNA, which can be broadly classified into interspersed repeats and tandem repeats

Question 23

The enzyme reverse transcriptase is crucial for the movement of:
a) DNA transposons
b) SINEs (Short Interspersed Nuclear Elements) like Alu repeats
c) Simple sequence repeats
d) Centromeric DNA

Answer 23

b) SINEs (Short Interspersed Nuclear Elements) like Alu repeats

SINEs are retrotransposons that rely on reverse transcriptase to convert their RNA transcripts back into DNA for insertion into the genome

Question 24

What is a key difference in gene organization between prokaryotes and eukaryotes?
a) Prokaryotes have linear chromosomes, while eukaryotes have circular chromosomes.
b) Eukaryotic genes often contain introns, which are typically absent in prokaryotic genes.
c) Prokaryotes have their DNA enclosed within a nucleus, while eukaryotes do not.
d) Eukaryotic genes are always organized into operons, unlike prokaryotic genes.

Answer 24

b) Eukaryotic genes often contain introns, which are typically absent in prokaryotic genes.

Eukaryotic genes are frequently interrupted by non-coding regions called introns, which are removed by splicing before translation. Prokaryotic genes generally lack introns

Question 25

Next Generation Sequencing (NGS) technologies are characterized by: a) Sequencing of single DNA molecules in real time. b) High-throughput sequencing of millions of DNA fragments in parallel. c) Chain-termination chemistry followed by gel electrophoresis. d) A low error rate and short read lengths.

Answer 25

b) High-throughput sequencing of millions of DNA fragments in parallel. NGS involves massively parallel sequencing, allowing for the simultaneous sequencing of millions of DNA templates

Question 26

A true-breeding plant with round seeds (RR) is crossed with a plant with wrinkled seeds (rr). The F1 generation all have round seeds (Rr). If two plants from the F1 generation are crossed, what proportion of the F2 generation would be expected to be heterozygous for this trait? a) 1/4 b) 1/2 c) 3/4 d) All of them

Answer 26

b) 1/2 The F1 cross is Rr x Rr. The Punnett square for this cross yields genotypes RR, Rr, Rr, and rr in a 1:2:1 ratio. Therefore, 2 out of 4, or 1/2, of the F2 generation is expected to be heterozygous (Rr)

Question 27

Which of the following scenarios would most likely lead to the manifestation of a recessive autosomal allele? a) The allele is present in a heterozygous individual. b) The allele exhibits complete dominance. c) Both parents are carriers for the allele. d) The allele is located on a non-autosomal chromosome.

Answer 27

c) Both parents are carriers for the allele Autosomal recessive inheritance requires two copies of the recessive allele for the trait to be expressed. If both parents are carriers (heterozygous), there is a 25% chance their offspring will inherit two copies of the recessive allele

Question 28

A genetic condition shows incomplete penetrance. An individual with a known disease-causing genotype for this condition: a) Will exhibit a more severe form of the phenotype. b) Will exhibit a milder form of the phenotype. c) May not exhibit any phenotype associated with the genotype. d) Will pass on the condition to all of their offspring.

Answer 28

c) May not exhibit any phenotype associated with the genotype Incomplete penetrance means that not all individuals with a particular genotype will express the expected phenotype

Question 29

Which of the following best explains the observation that males are more frequently affected by X-linked recessive disorders than females? a) Males inherit the affected X chromosome from their father. b) Males have two copies of the X chromosome, increasing their chance of inheriting the recessive allele. c) Males only have one X chromosome, so if they inherit the recessive allele on that chromosome, they will express the trait. d) The Y chromosome in males often carries dominant alleles that mask recessive alleles on the X chromosome.

Answer 29

c) Males only have one X chromosome, so if they inherit the recessive allele on that chromosome, they will express the trait Males have an XY chromosome composition. If their single X chromosome carries a recessive allele for a particular trait, there is no corresponding allele on the Y chromosome to mask its expression

Question 30

A chromosomal rearrangement in which a segment of a chromosome is reversed end-to-end is known as a(n): a) Deletion b) Duplication c) Inversion d) Translocation

Answer 30

c) Inversion An inversion involves a chromosome breaking in two places, and the broken segment being reinserted in the reverse orientation

Question 31

Non-disjunction during meiosis I results in gametes that have: a) The correct number of chromosomes. b) Half the normal number of chromosomes. c) An extra copy or a missing copy of an entire chromosome. d) Structural abnormalities within the chromosomes.

Answer 31

c) An extra copy or a missing copy of an entire chromosome Non-disjunction, the failure of homologous chromosomes to separate properly during meiosis I, leads to some gametes having an extra chromosome (n+1) and others missing a chromosome (n-1)

Question 32

Which molecular cytogenetic technique is most suitable for detecting microdeletions or microduplications that are too small to be observed by standard karyotyping? a) G banding b) Q banding c) Karyotyping d) Fluorescence in situ hybridization (FISH)

Answer 32

d) Fluorescence in situ hybridization (FISH) FISH uses fluorescently labeled DNA probes that can hybridize to specific regions of the genome, allowing the detection of submicroscopic deletions or duplications as small as 100 kb.

Question 33

The primary chemical difference between deoxyribose and ribose sugars in nucleic acids is the presence of a: a) Phosphate group at the 5' carbon. b) Hydroxyl group at the 2' carbon in ribose, which is absent in deoxyribose. c) Nitrogenous base attached to the 1' carbon. d) Methyl group in thymine that is absent in uracil.

Answer 33

b) Hydroxyl group at the 2' carbon in ribose, which is absent in deoxyribose Ribose has a hydroxyl (-OH) group on the 2' carbon, while deoxyribose has a hydrogen (-H) atom at this position

Question 34

Which of the following types of non-covalent interactions plays a crucial role in stabilizing the double helix structure of DNA by forming specific pairings between nitrogenous bases? a) Phosphodiester bonds b) Peptide bonds c) Glycosidic bonds d) Hydrogen bonds

Answer 34

d) Hydrogen bonds Hydrogen bonds form between the nitrogenous bases on opposite strands of the DNA double helix (A with T, and C with G), providing stability to the structure

Question 35

In the context of genomics, the term "annotation" primarily refers to: a) Determining the order of nucleotides in a DNA molecule. b) Comparing genome sequences across different species. c) Attaching biological information to genomic sequences. d) Identifying repetitive elements within a genome

Answer 35

c) Attaching biological information to genomic sequences Genome annotation is the process of identifying the locations of genes and other functional elements within the genome and assigning biological meaning to these sequences

Question 36

Which of the following is a key characteristic distinguishing eukaryotic genomes from prokaryotic genomes? a) The absence of protein-coding genes. b) A smaller overall genome size. c) The presence of a high proportion of non-coding DNA, including introns. d) The organization of genes into operons.

Answer 36

c) The presence of a high proportion of non-coding DNA, including introns Eukaryotic genomes are characterized by a large amount of non-coding DNA, including introns within genes and intergenic sequences, which is significantly more than in prokaryotic genomes. Prokaryotic genes are often organized into operons, which is not a common feature of eukaryotic genomes

Question 37

Plasmids, found in some prokaryotic cells, are best described as: a) Essential linear DNA molecules required for survival. b) Small circular DNA molecules that replicate independently of the main chromosome. c) Non-functional RNA molecules involved in gene regulation. d) Protein complexes that package and protect the bacterial DNA

Answer 37

b) Small circular DNA molecules that replicate independently of the main chromosome Plasmids are extrachromosomal, circular DNA molecules capable of independent replication and often carry genes that provide a selective advantage to the bacterium

Question 38

Retrotransposons, such as Alu repeats in the human genome, move through a mechanism that involves: a) Direct excision from one genomic location and insertion into another. b) The creation of an RNA intermediate that is reverse transcribed into DNA for insertion. c) Replication of the DNA element and insertion of the new copy at a distant site. d) The activity of transposase enzymes that recognize specific DNA sequences.

Answer 38

b) The creation of an RNA intermediate that is reverse transcribed into DNA for insertion Retrotransposons are mobile genetic elements that are transcribed into RNA, which is then reverse transcribed back into DNA by reverse transcriptase and inserted into a new location in the genome

Question 39

The C-value paradox refers to the observation that: a) The number of genes in an organism directly correlates with the size of its genome. b) Organisms with similar complexity can have vastly different genome sizes. c) Coding regions of genes (exons) are significantly larger than non-coding regions (introns). d) The rate of mutation is inversely proportional to the size of the genome.

Answer 39

b) Organisms with similar complexity can have vastly different genome sizes The C-value paradox highlights the lack of correlation between the genome size (C-value) of an organism and its perceived complexity

Question 40

During DNA replication, the enzyme responsible for synthesizing short RNA primers is: a) DNA polymerase III b) DNA ligase c) Helicase d) Primase

Answer 40

d) Primase Primase (dnaG) is an RNA polymerase that synthesizes short RNA primers, providing the 3'-OH group necessary for DNA polymerase to initiate DNA synthesis

Question 41

Which of the following is a key function of single-strand binding (SSB) proteins during DNA replication? a) To unwind the DNA double helix at the replication fork. b) To catalyse the formation of phosphodiester bonds between Okazaki fragments. c) To stabilise the separated DNA strands and prevent their reannealing. d) To add nucleotides to the growing DNA strand in a 5' to 3' direction.

Answer 41

c) To stabilize the separated DNA strands and prevent their reannealing SSB proteins bind to the single-stranded DNA created by helicase, preventing the strands from rejoining and ensuring that they remain available as templates for DNA synthesis

Question 42

The proofreading activity of DNA polymerase III relies on its: a) 5' to 3' exonuclease activity. b) Ability to add nucleotides only in the 5' to 3' direction. c) 3' to 5' exonuclease activity. d) Requirement for an RNA primer to initiate synthesis.

Answer 42

c) 3' to 5' exonuclease activity DNA polymerase III possesses a 3' to 5' exonuclease activity that allows it to detect and remove incorrectly incorporated nucleotides at the 3' end of the growing DNA strand, thus ensuring high fidelity of replication

Question 43

Telomerase, the enzyme responsible for maintaining telomere length, is a: a) DNA polymerase that synthesises DNA using a DNA template. b) RNA-dependent DNA polymerase that uses an RNA molecule as a template to synthesise DNA repeats. c) DNA ligase that joins telomeric DNA repeats. d) Nuclease that degrades damaged telomeric DNA.

Answer 43

b) RNA-dependent DNA polymerase that uses an RNA molecule as a template to synthesize DNA repeats Telomerase is a reverse transcriptase, meaning it uses its own RNA component as a template to synthesize the repetitive DNA sequences that constitute telomeres

Question 44

Which DNA repair mechanism is primarily responsible for correcting errors that occur during DNA replication and escape the proofreading activity of DNA polymerase? a) Base excision repair b) Nucleotide excision repair c) Mismatch repair d) Direct repair

Answer 44

c) Mismatch repair Mismatch repair systems recognise and correct base pair mismatches and small insertions or deletions that occur during DNA replication

Question 45

The direct repair of pyrimidine dimers in DNA, utilising light energy, is carried out by the enzyme: a) DNA glycosylase b) AP endonuclease c) DNA photolyase d) Excinuclease

Answer 45

c) DNA photolyase DNA photolyase is an enzyme that can directly reverse the formation of pyrimidine dimers caused by UV radiation by using light energy to break the covalent bonds linking the adjacent pyrimidines

Question 46

Next Generation Sequencing (NGS) technologies differ significantly from Sanger sequencing primarily due to their ability to: a) Sequence longer DNA fragments with higher accuracy. b) Simultaneously sequence millions of DNA fragments. c) Eliminate the need for PCR amplification. d) Directly determine the sequence of RNA molecules.

Answer 46

b) Simultaneously sequence millions of DNA fragments NGS technologies are characterized by massively parallel sequencing, allowing for the simultaneous analysis of millions to billions of DNA fragments, leading to much higher throughput compared to Sanger sequencing

Question 47

Long-read Next Generation Sequencing technologies are particularly advantageous for: a) Identifying single nucleotide polymorphisms with high accuracy. b) Quantifying gene expression levels. c) Resolving complex genomic rearrangements such as large insertions, deletions, and inversions. d) Sequencing highly fragmented DNA samples.

Answer 47

c) Resolving complex genomic rearrangements such as large insertions, deletions, and inversions The long read lengths produced by third-generation sequencing technologies (e.g., PacBio, Nanopore) are crucial for spanning large repetitive regions and identifying complex structural variants in the genome

Question 48

The use of dideoxynucleotide triphosphates (ddNTPs) is a key component of: a) Polymerase chain reaction (PCR). b) Next Generation Sequencing by synthesis. c) Sanger sequencing d) Gel electrophoresis for DNA fragment separation.

Answer 48

c) Sanger sequencing Sanger sequencing relies on the random incorporation of ddNTPs, which lack a 3'-OH group, causing chain termination at various points along the DNA template. These fragments of different lengths are then separated to determine the DNA sequence

Question 49

Comparative genomics can provide insights into evolutionary relationships by: a) Measuring the rate of protein synthesis in different species. b) Analyzing the differences and similarities in the DNA sequences of different organisms. c) Studying the expression patterns of specific genes across tissues. d) Determining the three-dimensional structure of conserved proteins.

Answer 49

b) Analyzing the differences and similarities in the DNA sequences of different organisms By comparing the genomes of different species, scientists can identify conserved sequences that may indicate shared ancestry and functional importance, as well as unique sequences that contribute to species-specific traits. The degree of difference in genomic sequences is generally proportional to the evolutionary distance between species

Question 50

Genome-Wide Association Studies (GWAS) are a powerful tool for: a) Identifying the complete genomic sequence of an individual. b) Determining the function of all genes in a genome. c) Finding associations between genetic variations and specific traits or diseases in large populations. d) Correcting disease-causing mutations in living organisms.

Answer 50

c) Finding associations between genetic variations and specific traits or diseases in large populations. GWAS involve scanning the genomes of many individuals with and without a particular trait or disease to identify genetic variants (typically SNPs) that are statistically associated with the phenotype

Question 51

According to Mendel's work with pea plants, which of the following characteristics was relatively easy to observe, making peas a suitable model organism? a) The ability to produce multiple offspring over a long lifespan b) Complex cellular structures requiring high-powered microscopy c) Easily distinguishable traits such as stem height and seed color d) A very large and complex genome requiring advanced sequencing techniques

Answer 51

c) Easily distinguishable traits such as stem height and seed color Mendel chose peas because they had relatively easy to observe characteristics such as stem height, seed color, seed shape, pod color, pod shape, flower color, and flower position

Question 52

What term describes individuals who have two identical alleles for a particular gene? a) Heterozygous b) Homozygous c) Hemizygous d) Phenotypic

Answer 52

b) Homozygous True-breeding individuals, in Mendelian genetics, are described as homozygous, meaning they have two identical alleles for a trait

Question 53

In a dihybrid cross involving two independently assorting genes, if both parents have the genotype TtPp, what is the expected phenotypic ratio of their offspring? a) 1:1:1:1 b) 3:1 c) 9:3:3:1 d) 1:2:1

Answer 53

c) 9:3:3:1 A dihybrid cross of two heterozygous individuals (TtPp x TtPp) for two independently assorting genes is expected to yield a 9:3:3:1 phenotypic ratio in the F2 generation

Question 54

Which of the following genetic disorders is an example of an autosomal dominant inheritance pattern? a) Albinism b) Cystic fibrosis c) Huntington’s disease d) Sickle cell anaemia

Answer 54

c) Huntington’s disease Huntington’s disease is listed as an example of a disorder caused by autosomal dominant inheritance. Albinism and cystic fibrosis are autosomal recessive, and sickle cell anaemia, while having complex inheritance aspects, is often considered autosomal recessive in its classic presentation

Question 55

If an individual has attached earlobes, which is a recessive trait, what is their genotype? a) EE b) Ee c) ee d) Cannot be determined from the information given

Answer 55

c) ee The gene for attached earlobes is recessive, and if you have attached earlobes, your genotype is ee

Question 56

What term describes a family tree that indicates the presence or absence of a trait for each member across generations, used to reveal patterns of inheritance? a) Punnett square b) Linkage map c) Pedigree d) Karyotype

Answer 56

c) Pedigree A pedigree is defined as a family tree indicating the presence or absence of a trait for each member of each generation, used to reveal patterns of inheritance

Question 57

Incomplete dominance is illustrated by the pitch of human male voices, where intermediate range baritones are heterozygous. What does this indicate about the alleles involved? a) One allele completely masks the other. b) Both alleles are equally and fully expressed. c) The heterozygous phenotype is a blend of the two homozygous phenotypes. d) Multiple genes contribute to the phenotype.

Answer 57

c) The heterozygous phenotype is a blend of the two homozygous phenotypes. The example of human male voice pitch illustrates intermediate expression, where the heterozygous individuals (baritones) show a phenotype between the two homozygous extremes

Question 58

Blood type O is caused by the IO allele, which results in no extra sugar residue on the H-antigen. If a homozygous Type B individual (IBIB) has a child with a heterozygous Type A individual (IAIO), what are the possible blood types of their offspring? a) Type A only b) Type B only c) Type AB and Type A d) Type AB and Type B

Answer 58

d) Type AB and Type B A Punnett square for IBIB x IAIO shows possible genotypes IAIB and IBIO, resulting in blood types AB and B, respectively

Question 59

Familial diabetes and obesity are given as examples of traits with less than 100% penetrance. What does this mean? a) Individuals with the genotype for these traits will always exhibit the phenotype but to varying degrees. b) Only a certain percentage of individuals with the genotype for these traits will actually develop the condition. c) These conditions are caused by multiple genes and environmental factors. d) The dominant allele for these traits is not very common in the population.

Answer 59

b) Only a certain percentage of individuals with the genotype for these traits will actually develop the condition. Penetrance is the percentage of individuals with a certain genotype who show the expected phenotype. A penetrance of less than 100% means that some individuals with the genotype will not exhibit the trait

Question 60

What is the term for a single gene being responsible for a variety of seemingly unrelated traits, as seen in albinism affecting pigmentation and vision? a) Polygenic inheritance b) Pleiotropy c) Epistasis d) Linkage

Answer 60

b) Pleiotropy Pleiotropy is defined as a single gene being responsible for a variety of traits, and albinism, affecting skin, hair, eye pigmentation, and vision.

Question 61

Who observed that chromosomes and genes both occur in pairs in diploid cells and that homologous chromosomes separate during meiosis? a) Gregor Mendel b) Walter Fleming c) Walter Sutton d) Thomas Hunt Morgan

Answer 61

c) Walter Sutton Walter Sutton, in 1902, observed the parallels between the behavior of chromosomes during meiosis and Mendel's laws of inheritance, concluding that Mendelian factors (genes) are located on chromosomes

Question 62

In humans, which parent determines the sex of the offspring? a) Mother only, as she always contributes an X chromosome. b) Father only, as he can contribute either an X or a Y chromosome. c) Both parents equally contribute to the sex of the offspring. d) It depends on which X chromosome is inactivated.

Answer 62

b) Father only, as he can contribute either an X or a Y chromosome. The sex of an individual is determined by the sex chromosomes. Females have XX and males have XY. Therefore, the father's contribution of either an X or a Y chromosome determines the sex of the offspring

Question 63

Haemophilia is an X-linked recessive disorder. If a carrier female has children with an unaffected male, what is the probability that their sons will have haemophilia? a) 0% b) 25% c) 50% d) 100%

Answer 63

c) 50% A carrier female has one normal X chromosome and one X chromosome with the recessive haemophilia allele. Her sons will inherit either the normal X (unaffected) or the affected X (haemophilia), each with a 50% probability

Question 64

What is a Barr body? a) A highly condensed region of autosomal chromosomes. b) An inactive X chromosome found in the nucleus of interphase cells in females. c) A structure formed during crossing over in meiosis. d) A region of the Y chromosome responsible for male sex determination.

Answer 64

b) An inactive X chromosome found in the nucleus of interphase cells in females. A Barr body is the highly condensed, inactive X chromosome in the somatic cells of females, resulting from X inactivation

Question 65

Genetic distance between two linked genes is expressed in what unit? a) Base pairs b) Genes per chromosome c) Map units d) Chromosomes per genome

Answer 65

c) Map units Genetic distance between two genes is expressed in map units, which are equivalent to the percentage of recombination frequency

Question 66

Down syndrome is most commonly caused by which type of chromosomal abnormality? a) Monosomy b) Trisomy c) Deletion d) Translocation

Answer 66

b) Trisomy Down syndrome (trisomy 21) is caused by an extra copy of chromosome 21

Question 67

Cri du chat syndrome is associated with which type of chromosomal abnormality? a) Trisomy of chromosome 18 b) Deletion of part of chromosome 5 c) Translocation between chromosome 9 and 22 d) Monosomy of the X chromosome

Answer 67

b) Deletion of part of chromosome 5 Cri du chat syndrome is caused by a deletion of a segment of chromosome 5

Question 68

Which of the following is a characteristic of Klinefelter syndrome in males? a) 45, X karyotype b) Increased fertility c) Low testosterone levels d) Below average height

Answer 68

c) Low testosterone levels Klinefelter syndrome (XXY) in males is often associated with low testosterone levels

Question 69

What is the term for an individual with two or more genetically different cell lines derived from a single zygote? a) Chimera b) Mosaic c) Hybrid d) Clone

Answer 69

b) Mosaic A mosaic organism has two or more genetically different cell lines that originated from a single zygote

Question 70

Amniocentesis is a prenatal genetic testing procedure that involves obtaining a sample of: a) Maternal blood b) Chorionic villi c) Amniotic fluid d) Fetal cells sorted from maternal circulation

Answer 70

c) Amniotic fluid Amniocentesis involves extracting a small sample of amniotic fluid surrounding the fetus, which contains fetal cells for genetic analysis

Question 71

The study of normal and abnormal chromosomes is known as: a) Molecular biology b) Genomics c) Cytogenetics d) Proteomics

Answer 71

c) Cytogenetics Cytogenetics is the branch of genetics that deals with the study of chromosomes, their structure, function, and abnormalities

Question 72

G banding is a cytogenetic technique that involves staining chromosomes with Giemsa stain. Which regions of DNA does this stain preferentially bind to? a) Regions rich in GC base pairs b) Regions rich in AT base pairs c) Centromeric regions d) Telomeric regions

Answer 72

b) Regions rich in AT base pairs G banding uses Giemsa stain to stain areas of DNA that are rich in AT base pairs

Question 73

Fluorescence in situ hybridization (FISH) uses DNA probes to: a) Amplify specific DNA sequences. b) Cut DNA at specific restriction sites. c) Hybridize to complementary DNA or RNA sequences, allowing visualization. d) Methylate specific regions of the genome.

Answer 73

c) Hybridize to complementary DNA or RNA sequences, allowing visualization. FISH involves using fluorescently labeled DNA probes that hybridize to specific complementary sequences on chromosomes, allowing their presence and location to be visualized

Question 74

Which of the following is a key goal of the Human Genome Project? a) To develop gene therapies for all known genetic diseases b) To identify all proteins encoded by the human genome c) To determine the complete nucleotide sequence of the human genome d) To understand the function of every gene in the human genome

Answer 74

c) To determine the complete nucleotide sequence of the human genome A primary goal of the Human Genome Project was to determine the sequences of the 3 billion base pairs that make up human DNA

Question 75

Next-generation sequencing (NGS) technologies are characterized by: a) Low throughput and long read lengths. b) High throughput and massively parallel sequencing. c) Sequencing of single DNA molecules. d) Dependence on dideoxy chain termination.

Answer 75

b) High throughput and massively parallel sequencing. Next Generation Sequencing (NGS) is based on the massive parallel sequencing method, allowing millions of DNA templates to be sequenced in one reaction

Question 76

The exponential growth in next generation sequence archives since 1990 is partly attributed to a significant decrease in the price to sequence a base, which fell over how many times from 1990 to 2010? a) 10 times b) 50 times c) 100 times d) 1000 times

Answer 76

c) 100 times The price to sequence a base has fallen over 100 times from 1990 to 2010

Question 77

The detection of cancer can be linked to mutations in which specific gene, with a deletion of approximately 2000 bases leading to a 90% predisposition to cancer? a) BRCA1 b) TP53 c) RAS d) APC

Answer 77

b) TP53 The detection of cancer is attributed to mutation in the TP53 gene, and a deletion of ~2000 bases in this gene results in a 90% predisposition to cancer

Question 78

The analysis of mutations in viruses, facilitated by genomic sequencing, has allowed us to observe how a virus affects its hosts. This was particularly important in understanding which recent global health event? a) The Spanish Flu pandemic b) The HIV/AIDS epidemic c) The COVID-19 pandemic d) The Ebola outbreak

Answer 78

c) The COVID-19 pandemic The analysis of mutations allowed the detection of viral variants and helped understand how the virus affects its hosts, citing COVID-19 as an example where this analysis was crucial

Question 79

Gregor Mendel’s work on inheritance initially focused on which organism due to its relatively easy-to-observe characteristics? a) Fruit flies b) Mice c) Peas d) Yeast

Answer 79

c) Peas Because their characteristics were relatively easy to observe

Question 80

Mendel's experiments involved mating true-breeding flowers, which exhibit only one phenotype for a particular trait. What genetic term describes individuals with two identical alleles for a trait? a) Heterozygous b) Homozygous c) Hemizygous d) Polygenic

Answer 80

b) Homozygous True-breeding individuals are defined as homozygous, meaning they have both alleles for a trait as the same

Question 81

In autosomal dominant inheritance, how many copies of the dominant allele are required for an individual to express the trait? a) Zero b) One c) Two d) It depends on the specific gene

Answer 81

b) One Autosomal dominant inheritance occurs when one autosomal allele masks the expression of the other allele, meaning inheriting just one copy of the dominant allele will cause the disorder

Question 82

Punnett squares are described in the source as standard tools used by which professionals to help determine the risk for genetically inherited diseases? a) Microbiologists b) Genetic counselors c) Epidemiologists d) Biotechnologists

Answer 82

b) Genetic counselors Punnett squares are mentioned as standard tools used by genetic counselors

Question 83

Which term describes the mating between two individuals who are closely related, increasing the chance of their offspring inheriting two copies of the same rare allele? a) Outcrossing b) Hybridization c) Consanguinous matings d) Test cross

Answer 83

c) Consanguinous matings Consanguinous matings as increasing the chance of mating between two carriers of the same rare allele

Question 84

Human stature, skin colour, hair colour, and eye colour are given as examples of traits that are typically determined by the combined effect of more than one pair of genes. What is this pattern of inheritance called? a) Incomplete dominance b) Codominance c) Polygenic inheritance d) Sex-linked inheritance

Answer 84

c) Polygenic inheritance Polygenic inheritance is determined by the combined effect of more than one pair of genes and provides the listed traits as examples

Question 85

In codominance, as exemplified by human blood types, how many alleles are expressed in heterozygous individuals? a) Only one allele b) Both alleles c) Neither allele d) A blended version of both alleles

Answer 85

b) Both alleles Codominance is defined as when two alleles are expressed in heterozygous individuals

Question 86

What term describes the phenomenon where a genotype is present in an individual, but the expected phenotype is absent? a) Expressivity b) Incomplete dominance c) Penetrance less than 100% d) Pleiotropy

Answer 86

c) Penetrance less than 100% Penetrance and states that some traits have a penetrance of <100%, meaning the genotype is present, but the phenotype is absent

Question 87

A single gene being responsible for a variety of traits, such as in albinism which affects pigmentation and vision, is known as: a) Epistasis b) Pleiotropy c) Polygeny d) Linkage

Answer 87

b) Pleiotropy Pleiotropy is defined as when a single gene may be responsible for a variety of traits, and albinism is given as an example

Question 88

In many animals, including humans and fruit flies, females typically have which combination of sex chromosomes? a) XY b) XX c) X0 d) YY

Answer 88

b) XX In humans and fruit flies, females have two X chromosomes

Question 89

Haemophilia, colourblindness, and Duchenne muscular dystrophy are listed as examples of traits that follow which pattern of inheritance? a) Autosomal dominant b) Autosomal recessive c) X-linked recessive d) Y-linked

Answer 89

c) X-linked recessive The X chromosome contains genes for these conditions and classifies them as X-linked recessive

Question 90

What is the term for the organized profile of a person’s chromosomes, used to identify genetic causes of diseases or disorders? a) Genotype b) Phenotype c) Karyotype d) Pedigree

Answer 90

c) Karyotype A karyotype is an organized profile of a person’s chromosomes that can help identify the genetic cause of a disease/disorder

Question 91

Down syndrome is cited as an example of which type of chromosomal abnormality, involving an extra copy of a chromosome? a) Monosomy b) Trisomy c) Deletion d) Translocation

Answer 91

b) Trisomy

Question 92

Turner syndrome in females is typically associated with which karyotype? a) 45, XX b) 45, XY c) 45, X d) 45, XXX

Answer 92

c) 45, X The genotype for Turner syndrome is X0, which corresponds to a karyotype with 45 chromosomes (44 autosomes + one X chromosome)

Question 93

Klinefelter syndrome in males is associated with which genotype? a) XY b) XX c) XYY d) XXY

Answer 93

d) XXY The table of sex chromosome abnormalities lists XXY as the male genotype for Klinefelter syndrome

Question 94

What term describes individuals who have two or more genetically different cell lines derived from a single zygote, resulting from a change such as a gene mutation or a chromosomal abnormality after fertilisation? a) Chimeras b) Mosaics c) Hybrids d) Mutants

Answer 94

b) Mosaics Mosaics having two or more genetically different cell lines derived from a single zygote, with the change occurring after fertilization

Question 95

Fluorescence in situ hybridization (FISH) is a molecular cytogenetic technique that uses what type of probes to visualize specific regions of the genome? a) Antibody-based probes b) Radioactive probes c) Fluorescently labeled DNA probes d) Enzyme-linked probes

Answer 95

c) Fluorescently labeled DNA probes FISH involves the use of DNA probes labeled with different colored fluorescent tags

Question 96

What is the basic repeating unit of chromatin, consisting of a segment of DNA wound around a histone protein core? a) Solenoid b) Chromatosome c) Nucleosome d) Scaffold protein

Answer 96

c) Nucleosome DNA wrapped around a histone core as being protected from nuclease, implying this structure is a fundamental unit

Question 97

Which of the following nitrogenous bases is a pyrimidine found in DNA? a) Adenine b) Guanine c) Thymine d) Uracil

Answer 97

c) Thymine Thymine is listed under the pyrimidines and specifically mentioned as being found in DNA

Question 98

What type of bond links the 5' phosphate group of one nucleotide to the 3' hydroxyl group of the next, forming the sugar-phosphate backbone of DNA? a) Hydrogen bond b) Glycosidic bond c) Peptide bond d) Phosphodiester bond

Answer 98

d) Phosphodiester bond The description of nucleotide linkage in DNA implies the formation of a phosphodiester bond

Question 99

The semi-conservative model of DNA replication, supported by the Messelsohn-Stahl experiment, results in each new DNA molecule consisting of: a) Two newly synthesized strands b) Two parental strands c) One parental strand and one newly synthesized strand d) A mixture of parental and new segments on both strands

Answer 99

c) One parental strand and one newly synthesized strand Semi-conservative replication as the separation of two complementary strands, with each individual strand acting as a parent template to create a new daughter strand

Question 100

In prokaryotic DNA replication, which enzyme is responsible for unwinding the double-stranded DNA at the origin of replication? a) DNA polymerase I b) DNA ligase c) Helicase d) Primase

Answer 100

c) Helicase Helicase is described as the enzyme that unwinds double-stranded DNA at the origin, ahead of the replication fork