For which nutrient study would the rat NOT be an appropriate model?

For which nutrient study would the rat NOT be an appropriate model?

• A. Vitamin C
• B. Protein
• C. Carbohydrates
• D. Calcium

Answer: (A)

The key idea is selecting a model organism whose nutrient needs reflect humans. For vitamin C, humans cannot synthesize it because they lack the enzyme L-gulonolactone oxidase, so dietary intake directly determines vitamin C status. Rats, however, can make vitamin C in the liver, so even with limited dietary vitamin C they typically do not develop deficiency symptoms. This endogenous production means a standard rat is not appropriate for studying human vitamin C requirements or deficiency effects, because the rat’s own synthesis hides the dietary need. To study vitamin C nutrition in a way that mirrors humans, you’d use an animal that cannot synthesize vitamin C (like guinea pigs or certain primates) or a rat modified to prevent synthesis. The other nutrients listed—protein, carbohydrates, and calcium—are well-suited to rat studies because rats metabolize and require these nutrients in ways that are informative for human nutrition as well.

The key idea is selecting a model organism whose nutrient needs reflect humans. For vitamin C, humans cannot synthesize it because they lack the enzyme L-gulonolactone oxidase, so dietary intake directly determines vitamin C status. Rats, however, can make vitamin C in the liver, so even with limited dietary vitamin C they typically do not develop deficiency symptoms. This endogenous production means a standard rat is not appropriate for studying human vitamin C requirements or deficiency effects, because the rat’s own synthesis hides the dietary need. To study vitamin C nutrition in a way that mirrors humans, you’d use an animal that cannot synthesize vitamin C (like guinea pigs or certain primates) or a rat modified to prevent synthesis. The other nutrients listed—protein, carbohydrates, and calcium—are well-suited to rat studies because rats metabolize and require these nutrients in ways that are informative for human nutrition as well.