A researcher wants to determine if a unicellular organism he discovered is an autotroph or a heterotroph. He radioactively labels the carbon in CO₂ and C₆H₁₂O₆, and exposes one culture of his organism to the labeled CO₂ and another culture to the labeled C₆H₁₂O₆. What would happen if his organism is an autotroph? A)Labeled carbon would be seen in the carbohydrates of organisms exposed to CO₂. B)Labeled carbon would be seen in the carbohydrates of organisms exposed to C₆H₁₂O₆. C)Labeled carbon would not be seen in the carbohydrates of either culture. D)Labeled carbon would be seen in carbohydrates of both cultures.

Question

Quizplus · Accepted Answer

If the organism is an autotroph, it will use the labeled carbon from CO₂ to produce carbohydrates through photosynthesis. Therefore, labeled carbon will be seen in the carbohydrates of the culture exposed to CO₂. However, if the organism is a heterotroph, it will break down the labeled carbon-containing compounds from C₆H₁₂O₆ to produce energy and cellular materials, leading to labeled carbon in the carbohydrates of neither culture.

A Researcher Wants to Determine If a Unicellular Organism He