OBQ case studies
OBQ · Put your knowledge to work in context.
The OBQ is a multiple-choice biology examination organised around seven weighted domains: Cell and Molecular Biology, Genetics and Genomics, Biochemistry and Metabolism, Organismal Biology, Ecology and Evolution, Quantitative Reasoning and Data Analysis, and Experimental Design and Laboratory Methods. The first five domains each carry roughly equal weight, quantitative reasoning matches them, and laboratory methods is the smallest component. That distribution rewards broad, even coverage rather than deep specialisation in one area, and it means a candidate who is strong in molecular biology but shaky on ecology or statistics loses ground quickly. The exam suits candidates who need to demonstrate working biological knowledge across scales, from molecular mechanisms through organismal physiology to populations and ecosystems, plus the quantitative and methodological skills that underpin experimental work. The OBQ case studies are 5 cases and about 2,531 words.
1The Stalled Replication Fork
A cultured human fibroblast line is treated with hydroxyurea, which depletes dNTP pools and stalls replication forks. Within 30 minutes, immunofluorescence shows RPA32 foci in 60% of nuclei, and western blot shows phosphorylation of CHK1 at Ser345.
502 words, about 3 min2Pedigree with Skewed X Inactivation
A family presents with an X-linked recessive disorder caused by a missense variant in a gene subject to X inactivation. The proband is a 7-year-old girl with mild symptoms.
549 words, about 3 min3Glycolysis in a Hypoxic Tumor Fragment
A tumor fragment is incubated in a sealed chamber with glucose and measured for lactate production and oxygen consumption. Under 21% O2, lactate output is 2.0 micromol/min/g and O2 consumption is 1.5 micromol/min/g.
481 words, about 2 min4Lizard Body Size Along an Elevation Gradient
A lizard species is sampled at five elevations: 200, 600, 1000, 1400, and 1800 m. Mean adult body mass decreases from 12.0 g at 200 m to 7.5 g at 1800 m.
508 words, about 3 min5qPCR Standard Curve with Inhibited Samples
A qPCR assay quantifies a bacterial gene from soil DNA. The standard curve uses purified plasmid DNA at 10^2 to 10^8 copies per reaction and gives a slope of -3.6 and R^2 of 0.998.
491 words, about 2 min