Question

each \turn\ of the calvin cycle adds how many carbon atoms from carbon dioxide?

○ six

○ one

○ three

○ two

Explanation:

The Calvin cycle is a part of photosynthesis. In each turn of the Calvin cycle, one molecule of carbon dioxide ($CO_2$) is fixed, and each $CO_2$ molecule has one carbon atom. So each turn adds one carbon atom from $CO_2$.

Answer:

B. one (assuming the option with "one" is labeled as such, e.g., if the "one" option is option B, then the answer is B. one; adjust the option label as per the actual question's numbering, but based on the content, the correct choice is the one with "one")