Practice Test 3

A lab tests the effect of an inhibitor of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) on anaerobic glycolysis in a facultative anaerobe at 37°C, pH 7.2. Cultures are supplied 10 mM glucose; after 10 minutes, intracellular metabolites are quantified.

Which metabolic change is most consistent with the data?

Table 1. Intracellular metabolite levels (mM) Condition: No inhibitor vs +GAPDH inhibitor

• G3P: 1.2 vs 4.8
• 1,3-BPG: 0.9 vs 0.1
• Pyruvate: 2.5 vs 0.6
• Lactate: 3.0 vs 0.7

A study examines temperature effects on growth of a mesophilic bacterium in rich medium at pH 7.0. Cultures are incubated at different temperatures, and specific growth rate ($\mu$, h$^{-1}$) is estimated during exponential phase.

Which conclusion is most supported by the experimental results?

Table 1. Temperature vs growth rate

• 25°C: $\mu=0.30$
• 30°C: $\mu=0.55$
• 37°C: $\mu=0.90$
• 45°C: $\mu=0.20$