Carbon Tracking in Photosynthesis Worksheet

Question 1

Which molecule could carry a carbon-13 label into the model as a reactant?

1. CO₂
2. H₂O
3. O₂
4. Light

Question 2

Use the net equation to compare the number of carbon atoms on the reactant and product sides for one glucose molecule formed.

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Question 3

Exactly two of the six CO₂ molecules used to make one glucose molecule contain a labeled carbon. How many labeled carbons does the glucose contain in this model? Explain.

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Question 4

A plant joins some of the glucose units it makes into starch. Where did the carbon in those glucose units originally enter the model?

1. As carbon dioxide
2. As water
3. As oxygen gas
4. As light energy

Question 5

Which observation best supports the claim that carbon from the air enters plant sugar?

1. The groups receive the same amount of light.
2. New sugar from A has a higher carbon-13 fraction after A receives enriched CO₂.
3. Both groups grow in the same medium.
4. Both groups receive the same amount of CO₂.

Question 6

Explain why group B helps the class interpret the sugar measurement from group A.

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Question 7

Which compound in the net model directly receives the traced carbon in the products?

1. O₂
2. H₂O
3. C₆H₁₂O₆
4. CO₂

Question 8

A student concludes that all carbon atoms in the sugar from group A must be carbon-13. Explain why the table cannot establish that claim.

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