Refer to the Graph Below Summarizing Data Collected Using Rubisco

question 235

Multiple Choice

Refer to the graph below summarizing data collected using rubisco purified from chloroplasts.It shows how the catalytic activity of rubisco changes in response to varying times of incubation, either with an oxidizing agent or with a reducing agent. Thioredoxin is a protein inside the stroma of a chloroplast that can act as an oxidizing or a reducing agent.Thioredoxin is reduced by ferredoxin in photosystem I.Based on this information and the graph, how do you predict thioredoxin will affect rubisco inside cells of a living plant when the plant is moved from the dark into the light?

• A) Rubisco activity will remain constant, as thioredoxin will not change.
• B) Rubisco activity will increase because thioredoxin will become a reducing agent.
• C) Rubisco activity will increase because thioredoxin will become an oxidizing agent.
• D) Rubisco activity will decrease because thioredoxin will become a reducing agent.
• E) Rubisco activity will decrease because thioredoxin will become an oxidizing agent.

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