MMSC491 Exam 2 Questions and Correct
ANSWER-s. With 100% Verified Solution.
2025/2026.
PART 1 — GENOME, GENE EXPRESSION & BASIC TERMINOLOGY
The term phenotype can be applied to a wide range of manifestations. Which of the following does NOT
constitute a phenotypic manifestation?
A. The number of digits a person has
B. The transcriptome of a single T cell
C. The sequence of a person's beta globin gene
D. Autistic behavior
Correct ANSWER✔✨-: C — a DNA sequence is genotype, not phenotype.
Rationale: A) digit number is a morphological phenotype; B) RNA expression levels are a molecular
phenotype; C) correct — nucleotide sequence describes the genotype; D) behavior is a recognized
behavioral phenotype.
Which statement is INCORRECT regarding dominant/recessive terminology?
A. The terms dominant and recessive apply equally to alleles and phenotypes
B. Dominant describes a phenotype manifested in the heterozygote
C. Recessive describes a phenotype manifest from the combined effects of both alleles
D. The AB blood group is an example of a co-dominant phenotype
Correct ANSWER✔✨-: A — the terms properly describe alleles, not phenotypes themselves.
Rationale: A) correct (incorrect statement) — dominance is a property of alleles relative to a phenotype;
B) true definition of dominant; C) true definition of recessive; D) true — both A and B antigens
expressed.
The genotype of an individual is best defined as:
A. The observable traits of the individual
B. The alleles/DNA sequence carried at a locus or genome-wide
,C. The protein profile of a cell
D. The chromosomal banding pattern
Correct ANSWER✔✨-: B.
Rationale: A) describes phenotype; B) correct — genotype is the genetic constitution; C) describes
proteome; D) describes karyotype, only one level of genotype.
A "wild-type" allele is:
A. The most common/standard allele in a population
B. Any disease-causing allele
C. An allele found only in laboratory animals
D. A duplicated allele
Correct ANSWER✔✨-: A.
Rationale: A) correct — wild-type is the reference/common allele; B) that is a mutant/pathogenic allele;
C) irrelevant; D) duplication is a mutation type, not wild-type.
Alleles are best defined as:
A. Alternative versions of the same gene at a locus
B. Different genes on one chromosome
C. Identical sister chromatids
D. Non-homologous DNA segments
Correct ANSWER✔✨-: A.
Rationale: A) correct; B) different genes are not alleles of each other; C) chromatids are copies, not
alleles; D) alleles require homology.
A compound heterozygote carries:
A. Two different mutant alleles at the same locus
B. Two identical mutant alleles
C. One mutant and one normal allele
D. Mutations in two different genes
Correct ANSWER✔✨-: A.
Rationale: A) correct (e.g., ΔF508 + G551D in CFTR); B) that is a true homozygote; C) that is a simple
carrier; D) that is digenic inheritance.
A male for an X-linked gene is described as:
,A. Hemizygous
B. Heterozygous
C. Homozygous
D. Dizygous
Correct ANSWER✔✨-: A.
Rationale: A) correct — only one X, so a single allele is expressed; B/C) require two alleles; D) refers to
twinning.
In incomplete dominance the heterozygote shows:
A. An intermediate phenotype between the two homozygotes
B. Full expression of both alleles
C. The recessive phenotype
D. No phenotype
Correct ANSWER✔✨-: A.
Rationale: A) correct (e.g., LDL levels in FH heterozygotes); B) describes co-dominance; C) describes
complete dominance; D) describes silencing, not dominance.
Co-dominance is exemplified by:
A. The ABO (AB) blood group
B. Albinism
C. Huntington disease
D. Turner syndrome
Correct ANSWER✔✨-: A.
Rationale: A) correct — both A and B antigens fully expressed; B) recessive trait; C) dominant trait; D)
chromosomal disorder.
Approximately what fraction of the human genome encodes protein?
A. ~1–2%
B. ~25%
C. ~50%
D. ~90%
Correct ANSWER✔✨-: A.
, Rationale: A) correct — exons are a tiny fraction; B/C/D) far too high; most genome is non-
coding/intronic/intergenic.
The number of protein-coding genes in the human genome is closest to:
A. 20,000–25,000
B. 100,000
C. 1 million
D. 3,000
Correct ANSWER✔✨-: A.
Rationale: A) correct per genome annotation; B) pre-genome estimate, too high; C) absurd; D) too low
(bacterial scale).
Introns are:
A. Intervening sequences removed by splicing
B. Coding sequences retained in mRNA
C. Promoter elements
D. Telomeric repeats
Correct ANSWER✔✨-: A.
Rationale: A) correct; B) those are exons; C) promoters regulate transcription upstream; D) telomeres
cap chromosome ends.
Which process converts RNA back into DNA?
A. Reverse transcription
B. Translation
C. Splicing
D. Methylation
Correct ANSWER✔✨-: A.
Rationale: A) correct — reverse transcriptase (retroviruses, retrotransposons); B) makes protein from
mRNA; C) removes introns; D) is an epigenetic modification.
Epigenetic inheritance refers to:
A. Heritable changes in gene expression without DNA sequence change
B. New DNA mutations each generation
C. Chromosome loss at meiosis
ANSWER-s. With 100% Verified Solution.
2025/2026.
PART 1 — GENOME, GENE EXPRESSION & BASIC TERMINOLOGY
The term phenotype can be applied to a wide range of manifestations. Which of the following does NOT
constitute a phenotypic manifestation?
A. The number of digits a person has
B. The transcriptome of a single T cell
C. The sequence of a person's beta globin gene
D. Autistic behavior
Correct ANSWER✔✨-: C — a DNA sequence is genotype, not phenotype.
Rationale: A) digit number is a morphological phenotype; B) RNA expression levels are a molecular
phenotype; C) correct — nucleotide sequence describes the genotype; D) behavior is a recognized
behavioral phenotype.
Which statement is INCORRECT regarding dominant/recessive terminology?
A. The terms dominant and recessive apply equally to alleles and phenotypes
B. Dominant describes a phenotype manifested in the heterozygote
C. Recessive describes a phenotype manifest from the combined effects of both alleles
D. The AB blood group is an example of a co-dominant phenotype
Correct ANSWER✔✨-: A — the terms properly describe alleles, not phenotypes themselves.
Rationale: A) correct (incorrect statement) — dominance is a property of alleles relative to a phenotype;
B) true definition of dominant; C) true definition of recessive; D) true — both A and B antigens
expressed.
The genotype of an individual is best defined as:
A. The observable traits of the individual
B. The alleles/DNA sequence carried at a locus or genome-wide
,C. The protein profile of a cell
D. The chromosomal banding pattern
Correct ANSWER✔✨-: B.
Rationale: A) describes phenotype; B) correct — genotype is the genetic constitution; C) describes
proteome; D) describes karyotype, only one level of genotype.
A "wild-type" allele is:
A. The most common/standard allele in a population
B. Any disease-causing allele
C. An allele found only in laboratory animals
D. A duplicated allele
Correct ANSWER✔✨-: A.
Rationale: A) correct — wild-type is the reference/common allele; B) that is a mutant/pathogenic allele;
C) irrelevant; D) duplication is a mutation type, not wild-type.
Alleles are best defined as:
A. Alternative versions of the same gene at a locus
B. Different genes on one chromosome
C. Identical sister chromatids
D. Non-homologous DNA segments
Correct ANSWER✔✨-: A.
Rationale: A) correct; B) different genes are not alleles of each other; C) chromatids are copies, not
alleles; D) alleles require homology.
A compound heterozygote carries:
A. Two different mutant alleles at the same locus
B. Two identical mutant alleles
C. One mutant and one normal allele
D. Mutations in two different genes
Correct ANSWER✔✨-: A.
Rationale: A) correct (e.g., ΔF508 + G551D in CFTR); B) that is a true homozygote; C) that is a simple
carrier; D) that is digenic inheritance.
A male for an X-linked gene is described as:
,A. Hemizygous
B. Heterozygous
C. Homozygous
D. Dizygous
Correct ANSWER✔✨-: A.
Rationale: A) correct — only one X, so a single allele is expressed; B/C) require two alleles; D) refers to
twinning.
In incomplete dominance the heterozygote shows:
A. An intermediate phenotype between the two homozygotes
B. Full expression of both alleles
C. The recessive phenotype
D. No phenotype
Correct ANSWER✔✨-: A.
Rationale: A) correct (e.g., LDL levels in FH heterozygotes); B) describes co-dominance; C) describes
complete dominance; D) describes silencing, not dominance.
Co-dominance is exemplified by:
A. The ABO (AB) blood group
B. Albinism
C. Huntington disease
D. Turner syndrome
Correct ANSWER✔✨-: A.
Rationale: A) correct — both A and B antigens fully expressed; B) recessive trait; C) dominant trait; D)
chromosomal disorder.
Approximately what fraction of the human genome encodes protein?
A. ~1–2%
B. ~25%
C. ~50%
D. ~90%
Correct ANSWER✔✨-: A.
, Rationale: A) correct — exons are a tiny fraction; B/C/D) far too high; most genome is non-
coding/intronic/intergenic.
The number of protein-coding genes in the human genome is closest to:
A. 20,000–25,000
B. 100,000
C. 1 million
D. 3,000
Correct ANSWER✔✨-: A.
Rationale: A) correct per genome annotation; B) pre-genome estimate, too high; C) absurd; D) too low
(bacterial scale).
Introns are:
A. Intervening sequences removed by splicing
B. Coding sequences retained in mRNA
C. Promoter elements
D. Telomeric repeats
Correct ANSWER✔✨-: A.
Rationale: A) correct; B) those are exons; C) promoters regulate transcription upstream; D) telomeres
cap chromosome ends.
Which process converts RNA back into DNA?
A. Reverse transcription
B. Translation
C. Splicing
D. Methylation
Correct ANSWER✔✨-: A.
Rationale: A) correct — reverse transcriptase (retroviruses, retrotransposons); B) makes protein from
mRNA; C) removes introns; D) is an epigenetic modification.
Epigenetic inheritance refers to:
A. Heritable changes in gene expression without DNA sequence change
B. New DNA mutations each generation
C. Chromosome loss at meiosis
