BIOLOGY 413 GENETICS AND
GENOMICS FINAL EXAM
Comprehensive Final Examination Questions and Answers Verified
Solutions 2026 2027
1. What fundamental principle of Mendelian inheritance states that two alleles for a gene
separate during gamete formation so that each gamete carries only one allele?
A. Law of Independent Assortment
B. Law of Segregation
C. Law of Dominance
D. Principle of Linkage
Rationale: Mendel's Law of Segregation dictates that homologous chromosomes (and their respective
alleles) separate during meiosis I, ensuring each gamete receives a single allele for each gene.
2. In a dihybrid cross between two individuals heterozygous for two unlinked genes
(AaBb x AaBb), what phenotypic ratio is expected in the offspring under complete
dominance?
A. 1:2:1
B. 3:1
C. 9:3:3:1
D. 1:1:1:1
Rationale: Independent assortment of two heterozygous unlinked genes yields a classical 9:3:3:1
phenotypic ratio representing double dominant, two single dominant/recessive combinations, and double
recessive phenotypes.
3. Which genetic term describes a situation where a single gene influences multiple
seemingly unrelated phenotypic traits?
A. Pleiotropy
B. Epistasis
C. Polygenic inheritance
D. Codominance
,Rationale: Pleiotropy occurs when one gene mutation affects multiple physiological systems or traits,
such as in Marfan syndrome or Sickle Cell Anemia.
4. What phenomenon occurs when the expression of one gene masks or modifies the
phenotypic expression of a completely different gene?
A. Incomplete dominance
B. Epistasis
C. Expressivity
D. Penetrance
Rationale: Epistasis involves gene-gene interaction where an epistatic gene overrides the allele
expression at a hypostatic locus, modifying classical Mendelian ratios.
5. What calculation determines the recombination frequency between two linked genes
on the same chromosome?
A. Total offspring divided by recombinant offspring multiplied by 100
B. Recombinant offspring divided by total offspring multiplied by 100
C. Parental offspring minus recombinant offspring divided by 2
D. Total progeny multiplied by Map Units
Rationale: Recombination frequency equals (Number of Recombinant Progeny / Total Progeny) x 100,
expressed as map units (m.u.) or centimorgans (cM).
6. One centimorgan (1 cM) is defined as equivalent to what percentage of recombination
frequency between two gene loci?
A. 0.1%
B. 1%
C. 10%
D. 50%
Rationale: A centimorgan (cM) is a unit of genetic mapping distance defined as the distance between
chromosome positions that yields a 1% recombination frequency.
7. What probability rule is used to calculate the likelihood of two independent genetic
events occurring together (e.g., event A AND event B)?
, A. Multiplication Rule (Product Rule)
B. Addition Rule (Sum Rule)
C. Binomial Expansion Rule
D. Chi-Square Goodness-of-Fit
Rationale: The product rule states that the probability of two independent events occurring simultaneously
is the product of their individual probabilities.
8. What statistical test determines whether observed offspring ratios significantly differ
from expected Mendelian ratios?
A. Student's t-test
B. ANOVA
C. Chi-Square Goodness-of-Fit Test
D. Pearson Correlation
Rationale: The Chi-Square (x2) goodness-of-fit test evaluates whether deviations between observed and
expected genetic experimental counts are due to random chance or true genetic deviation.
9. Which non-Mendelian inheritance pattern exhibits maternal inheritance because
offspring receive the organelle genome exclusively from the egg cell?
A. Sex-linked recessive
B. Mitochondrial inheritance
C. Genomic imprinting
D. Holandric inheritance
Rationale: Mitochondria (and chloroplasts) are inherited cytoplasmically from the maternal oocyte,
meaning mothers pass mitochondrial traits to all offspring, but fathers pass none.
10. What epigenetic mechanism silences a specific parental allele via DNA methylation
so that only the allele from the other parent is expressed?
A. Dosage compensation
B. Genomic Imprinting
C. Position-effect variegation
D. X-inactivation
Rationale: Genomic imprinting involves parent-of-origin specific epigenetic marking (methylation), causing
differential expression of maternal versus paternal alleles.
GENOMICS FINAL EXAM
Comprehensive Final Examination Questions and Answers Verified
Solutions 2026 2027
1. What fundamental principle of Mendelian inheritance states that two alleles for a gene
separate during gamete formation so that each gamete carries only one allele?
A. Law of Independent Assortment
B. Law of Segregation
C. Law of Dominance
D. Principle of Linkage
Rationale: Mendel's Law of Segregation dictates that homologous chromosomes (and their respective
alleles) separate during meiosis I, ensuring each gamete receives a single allele for each gene.
2. In a dihybrid cross between two individuals heterozygous for two unlinked genes
(AaBb x AaBb), what phenotypic ratio is expected in the offspring under complete
dominance?
A. 1:2:1
B. 3:1
C. 9:3:3:1
D. 1:1:1:1
Rationale: Independent assortment of two heterozygous unlinked genes yields a classical 9:3:3:1
phenotypic ratio representing double dominant, two single dominant/recessive combinations, and double
recessive phenotypes.
3. Which genetic term describes a situation where a single gene influences multiple
seemingly unrelated phenotypic traits?
A. Pleiotropy
B. Epistasis
C. Polygenic inheritance
D. Codominance
,Rationale: Pleiotropy occurs when one gene mutation affects multiple physiological systems or traits,
such as in Marfan syndrome or Sickle Cell Anemia.
4. What phenomenon occurs when the expression of one gene masks or modifies the
phenotypic expression of a completely different gene?
A. Incomplete dominance
B. Epistasis
C. Expressivity
D. Penetrance
Rationale: Epistasis involves gene-gene interaction where an epistatic gene overrides the allele
expression at a hypostatic locus, modifying classical Mendelian ratios.
5. What calculation determines the recombination frequency between two linked genes
on the same chromosome?
A. Total offspring divided by recombinant offspring multiplied by 100
B. Recombinant offspring divided by total offspring multiplied by 100
C. Parental offspring minus recombinant offspring divided by 2
D. Total progeny multiplied by Map Units
Rationale: Recombination frequency equals (Number of Recombinant Progeny / Total Progeny) x 100,
expressed as map units (m.u.) or centimorgans (cM).
6. One centimorgan (1 cM) is defined as equivalent to what percentage of recombination
frequency between two gene loci?
A. 0.1%
B. 1%
C. 10%
D. 50%
Rationale: A centimorgan (cM) is a unit of genetic mapping distance defined as the distance between
chromosome positions that yields a 1% recombination frequency.
7. What probability rule is used to calculate the likelihood of two independent genetic
events occurring together (e.g., event A AND event B)?
, A. Multiplication Rule (Product Rule)
B. Addition Rule (Sum Rule)
C. Binomial Expansion Rule
D. Chi-Square Goodness-of-Fit
Rationale: The product rule states that the probability of two independent events occurring simultaneously
is the product of their individual probabilities.
8. What statistical test determines whether observed offspring ratios significantly differ
from expected Mendelian ratios?
A. Student's t-test
B. ANOVA
C. Chi-Square Goodness-of-Fit Test
D. Pearson Correlation
Rationale: The Chi-Square (x2) goodness-of-fit test evaluates whether deviations between observed and
expected genetic experimental counts are due to random chance or true genetic deviation.
9. Which non-Mendelian inheritance pattern exhibits maternal inheritance because
offspring receive the organelle genome exclusively from the egg cell?
A. Sex-linked recessive
B. Mitochondrial inheritance
C. Genomic imprinting
D. Holandric inheritance
Rationale: Mitochondria (and chloroplasts) are inherited cytoplasmically from the maternal oocyte,
meaning mothers pass mitochondrial traits to all offspring, but fathers pass none.
10. What epigenetic mechanism silences a specific parental allele via DNA methylation
so that only the allele from the other parent is expressed?
A. Dosage compensation
B. Genomic Imprinting
C. Position-effect variegation
D. X-inactivation
Rationale: Genomic imprinting involves parent-of-origin specific epigenetic marking (methylation), causing
differential expression of maternal versus paternal alleles.
