Identifying carboxysomes in a bacterium suggests it
A) contains the reverse citric acid cycle.
B) has a deficient Calvin cycle and accumulated CO₂.
C) is in a carboxylic acid rich environment and is storing excess quantities for potentially harsh conditions.
D) will use the Calvin cycle convert the concentrated CO₂ into biomass.

Question

Quizplus · Accepted Answer

Carboxysomes are protein-bound organelles that contain the key enzymes necessary for the fixation of carbon dioxide via the Calvin cycle. Therefore, identifying carboxysomes in a bacterium suggests that it will use the Calvin cycle to convert the concentrated CO₂ into biomass. Option A is incorrect because the reverse citric acid cycle involves the conversion of acetyl-CoA into pyruvate and CO₂ via a series of complex reactions. Option B is incorrect because the accumulation of CO₂ in a deficient Calvin cycle would not necessarily lead to the formation of carboxysomes. Option C is incorrect because there is no evidence to suggest that carboxysomes are used for the storage of excess carboxylic acids.

Identifying Carboxysomes in a Bacterium Suggests It