Actual Questions & Answers — 70 Questions and Answers
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Subject Area Genetics
Description This comprehensive final exam covers advanced topics in genetics including
Mendelian and non-Mendelian inheritance, molecular genetics, population
genetics, epigenetics, and genomics. It assesses the ability to apply genetic
principles to complex scenarios, interpret experimental data, and understand
current genetic technologies and ethical considerations.
Expected Grade A+
Total Questions 70
Duration 3 hours
Learning Outcomes 1. Analyze complex inheritance patterns and calculate genetic probabilities in
pedigrees.
2. Interpret molecular genetic data including DNA replication, transcription,
translation, and mutation analysis.
3. Apply population genetics principles to calculate allele frequencies and predict
evolutionary changes.
4. Evaluate epigenetic mechanisms and their role in gene regulation and disease.
5. Critically assess genetic technologies such as CRISPR, gene therapy, and
genomic sequencing in research and clinical contexts.
Accreditation This exam meets the rigorous standards of accredited US universities (Ivy League
/ R1 research level) and reflects current genetic knowledge and practices as of
2026.
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,1. In a species of flowering plant, flower color is determined by two unlinked genes:
Gene A and Gene B. The presence of at least one dominant allele at both genes (A_
B_) results in purple flowers. All other genotypes produce white flowers. If a double
heterozygote (AaBb) is self-crossed, what proportion of the offspring are expected to
have purple flowers?
A. 9/16
B. 7/16
C. 3/4
D. 1/2
Answer: A. 9/16
This is a classic dihybrid cross with complementary gene interaction. The Punnett
square yields 9 A_B_ (purple) out of 16 total offspring, so the proportion is 9/16. The
other options represent incorrect ratios from other types of epistasis.
2. A researcher is studying a rare autosomal recessive disorder in a small, isolated
population. The disorder has a frequency of 1 in 10,000 births. Assuming
Hardy-Weinberg equilibrium, what is the frequency of carriers (heterozygotes) in
the population?
A. 0.0001
B. 0.0198
C. 0.0200
D. 0.0002
Answer: B. 0.0198
Given q^2 = 1/10000 = 0.0001, q = 0.01, p = 0.99. Carrier frequency = 2pq = 2 * 0.99 *
0.01 = 0.0198. Option C (0.02) is approximate but less precise; A and D are incorrect.
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,3. In a genetic screen, you isolate a mutant strain of yeast that cannot grow on
minimal medium but can grow when supplemented with arginine. You clone the
wild-type gene and sequence it. The mutation is a single base substitution that
changes a codon from UGG to UGA. What is the most likely molecular consequence
of this mutation?
A. Missense mutation leading to a different amino acid
B. Nonsense mutation leading to premature termination
C. Silent mutation with no effect on protein sequence
D. Frameshift mutation altering all downstream amino acids
Answer: B. Nonsense mutation leading to premature termination
UGG codes for tryptophan, while UGA is a stop codon. Thus the mutation introduces a
premature stop, resulting in a truncated protein. This is a nonsense mutation. The other
options are incorrect because the codon change does not cause a frameshift, is not silent,
and is not missense (it's nonsense).
4. Which of the following best describes the role of DNA methylation in gene
regulation?
A. Methylation of histones generally activates transcription by loosening chromatin.
B. Methylation of CpG islands in promoter regions is typically associated with
transcriptional repression.
C. DNA methylation occurs exclusively on cytosine bases in all sequence contexts.
D. DNA methylation patterns are never inherited after cell division.
Answer: B. Methylation of CpG islands in promoter regions is typically associated
with transcriptional repression.
Methylation of CpG islands in promoters recruits methyl-binding proteins and
compacts chromatin, repressing transcription. Option A is incorrect because histone
acetylation (not methylation) generally loosens chromatin; histone methylation can
activate or repress. Option C is false: in mammals, methylation is mostly on CpG
dinucleotides. Option D is false: methylation patterns are maintained through cell
division by maintenance methyltransferases.
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, 5. A researcher performs a bacterial transformation experiment using a strain that is
auxotrophic for leucine (leu-) and resistant to ampicillin (AmpR). She isolates DNA
from a wild-type strain that is prototrophic for leucine (leu+) and sensitive to
ampicillin (AmpS). She treats the recipient leu- AmpR cells with this DNA and then
plates them on minimal medium lacking leucine but containing ampicillin. What
type of transformants will grow on this plate?
A. Cells that are leu+ and AmpS
B. Cells that are leu+ and AmpR
C. Cells that are leu- and AmpR
D. Only cells that have not taken up any DNA
Answer: B. Cells that are leu+ and AmpR
The selective plate requires leucine prototrophy (leu+) and ampicillin resistance
(AmpR). The donor DNA provides leu+ but not AmpR. However, the recipient cells
already have AmpR. Only cells that have incorporated the leu+ gene (from donor DNA)
while retaining their own AmpR will grow. Option A would be sensitive to ampicillin, C
cannot grow without leucine, D cannot grow without leucine.
6. In a population of 1000 individuals, a researcher genotypes a single nucleotide
polymorphism (SNP) and finds 490 AA, 420 Aa, and 90 aa. Is this population in
Hardy-Weinberg equilibrium for this SNP?
A. Yes, because the observed genotype frequencies match expected frequencies.
B. No, because there is an excess of heterozygotes.
C. No, because there is a deficiency of heterozygotes.
D. Cannot be determined without allele frequencies.
Answer: C. No, because there is a deficiency of heterozygotes.
Calculate allele frequencies: p = (2*490 + 420)/2000 = 0.7, q = 0.3. Expected HWE: AA
= 0.49*1000 = 490, Aa = 2*0.7*0.3*1000 = 420, aa = 0.09*1000 = 90. Observed equals
expected, so the population is in HWE. The correct answer is A. However, note the
options: A says yes, B and C say no. Since observed match expected, the answer is A.
Explanation: The numbers exactly match HWE expectations, so no deviation. B and C
are incorrect because there is neither excess nor deficiency.
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