Question

the radioactive isotope used in the calvin experiments was

nitrogen - 15

carbon - 12

carbon - 14

boron - 8

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part b

the calvin cycle describes the conversion of

carbohydrates to proteins

carbon dioxide to carbohydrates

water to carbon dioxide

carbon dioxide to amino acids

Explanation:

• Part A: In the Calvin experiments, carbon - 14 (\(^{14}C\)) was used as a radioactive isotope. This was because carbon is a key element in the carbon fixation process of photosynthesis (which the Calvin cycle is a part of), and \(^{14}C\) could be traced through the reactions. Nitrogen - 15 (\(^{15}N\)) is not relevant to the carbon - based reactions of the Calvin cycle. Carbon - 12 (\(^{12}C\)) is a stable non - radioactive isotope. Boron - 8 (\(^{8}B\)) is not involved in the major components of the Calvin cycle reactions.
• Part B: The Calvin cycle is a series of reactions in photosynthesis. Its main function is to fix carbon dioxide (\(CO_2\)). It takes \(CO_2\) and, using the energy from ATP and NADPH (produced in the light - dependent reactions), converts it into carbohydrates (such as glucose). Carbohydrates to proteins is not the function of the Calvin cycle. Water to carbon dioxide is not the direction of the reaction in the Calvin cycle (water is split in the light - dependent reactions). Carbon dioxide to amino acids is not the direct conversion in the Calvin cycle; the Calvin cycle first makes carbohydrates.

Answer:

• Part A: carbon - 14
• Part B: carbon dioxide to carbohydrates