Practice Test 1 - Genetics

20 questions. Answer them in any order, then submit to see your score and every explanation.

A nonsense mutation early in a prokaryotic gene creates a premature stop codon. This is observed to cause a significant reduction in the amount of full-length mRNA transcribed from this gene and any downstream genes in the same operon. This phenomenon, known as polarity, is a consequence of which mechanism?
A researcher measures gene expression in treated vs. untreated cells. In treated cells, MYC expression is 300 units and housekeeping gene GAPDH is 1500 units. In untreated cells, MYC is 50 units and GAPDH is 1000 units. Which calculation correctly determines the normalized log₂(fold change) of MYC expression?
A scientist is studying a plant species where individuals can be either red-flowered or white-flowered. They hypothesize that a new pesticide reduces the fitness of plants with the dominant red-flower allele. They set up 10 plots with the pesticide and 10 plots without. Each plot starts with a 1:1 ratio of red- to white-flowered plants. If the 10 pesticide plots are all located in a sunny, southern-facing field, while the 10 control plots are in a shady, northern-facing field, what is the most critical flaw in this experimental design?
A three-point test cross yields an interference value of 1.0. Which statement is the least likely to be true about the genes being studied?
Assume genes A and B are linked on the same chromosome. In the absence of crossing over, how does the inheritance of alleles A and a relate to the inheritance of alleles B and b?
A three-point test cross was performed using a P/p ; R/r ; S/s heterozygote. The resulting data showed that the parental gametes were P r S and p R s. The double-crossover gametes were p r s and P R S. What is the order of the genes?
A researcher is analyzing an RNA-seq dataset comparing cancer cells to normal cells and has generated the volcano plot shown. Each point represents a single gene. The researcher is looking for a potential therapeutic target that is strongly upregulated but requires further validation due to high variance between biological replicates. Which point on the plot best represents such a gene?
Humans and chimpanzees share a nearly identical protein-coding sequence for the FOXP2 gene. However, the timing and level of its expression in the developing brain differ significantly between the two species. This difference in expression is hypothesized to contribute to uniquely human language abilities. What is the most likely genetic basis for this species-specific difference in FOXP2 regulation?
Gene Glo1 is regulated by two distal regulatory elements. Element 1 is a strong enhancer, and Element 2 is a silencer. In erythroid precursor cells, an activator (Act-E) binds Element 1, and a repressor (Rep-S) is absent. In myeloid precursor cells, Act-E binds Element 1, but Rep-S binds to Element 2. What are the predicted expression levels of Glo1 in these two cell types?
A pedigree spanning four generations shows a rare trait where every affected individual is male, and all sons of affected males are also affected. No daughters of affected males are affected. Which of the following observations, if discovered, would be most inconsistent with Y-linked inheritance?
A plant breeder is performing a trihybrid test cross. The three genes are linked in the order R-S-T. The map distance between R and S is 20 cM and between S and T is 20 cM. Interference in this region is 0.5. What is the expected frequency of parental gametes (R S T and r s t) from the trihybrid parent?
Height in humans is a classic example of a polygenic trait, with contributions from hundreds of genes and significant environmental influence. Given this understanding, which of the following observations from a large-scale study of human height would be the most surprising or unexpected?
A disorder is characterized by a high mutation rate in mitochondrial DNA, leading to an accumulation of somatic mtDNA mutations with age. This process is thought to contribute to age-related decline in tissues with high energy demands. How does this phenomenon of somatic mtDNA mutation accumulation differ from the inheritance of a classic mitochondrial disease like MELAS syndrome?
In a three-point mapping experiment, why are the double-crossover progeny the least frequent class found?
Refer to the pedigree, which shows the inheritance of ABO blood types in a family. Individuals with unknown blood types are indicated by a question mark. Individual II-2 marries individual II-4, who has Type B blood and whose mother had Type O blood. Based on the pedigree, what is the probability that their first child (III-1) will have Type B blood?
A researcher introduces a synthetic, 21-nucleotide double-stranded RNA (dsRNA) into mammalian cells that is perfectly complementary to a sequence in the coding region of Gene X mRNA. A significant, rapid reduction in the mRNA level of Gene X is observed. This result is most consistent with the activation of which pathway?
Which of the following would increase the calculated chi-square value for a given experiment, assuming the null hypothesis and total number of progeny remain the same?
A scientist obtains a tumor sample and measures the mRNA level for gene VEGF, finding it to be 150 units. The scientist concludes that VEGF is upregulated in this tumor, promoting angiogenesis. Why is this conclusion not supported by the data provided?
Which crossing strategy and resulting observation would most efficiently map the mutation m to a specific chromosomal region?
A geneticist has a male mouse displaying a dominant, autosomal phenotype, "jerker" (J_). She wants to determine if the mouse is homozygous (JJ) or heterozygous (Jj). Which of the following crosses represents the most appropriate and direct test cross?

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