If the gene encoding the enzyme rubisco is mutated such that it is non-functional, the process that would be affected is the ability to

Question

A.  make ATP.
B.  harvest photons.
C.  fix carbon.
D.  make O2.
E.  make NADPH.

Clarify Question
What is the key concept addressed by the question?
What type of thinking is required?

  Gather Content
What do you already know about photo synthetic processes? What other information is related to the question?
   Choose Answer
Do you have the necessary information to dissect the problem?

  Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

C.  fix carbon.

Clarify Question
What is the key concept addressed by the question?
        · The question asks you to determine which photosynthetic process would be affected by a rubisco enzyme loss-of-function mutation.
What type of thinking is required?
        · You are being asked to dissect, or analyze, the photosynthetic process most likely to be affected by a rubisco enzyme mutation that destroys its function.

  Gather Content
What do you already know about photo synthetic processes? What other information is related to the question?
        · The first phase of photosynthesis includes the light reactions, where energy from the sun is captured using chlorophyll molecules localized in Photo systems I and II to remove electrons from water, excite them to a higher energy level, and to use redox reactions in order to produce ATP and NADPH.
        · Remember that the light reactions, which include photosystems I and II, absorb light, make oxygen by splitting water and produce ATP and NADPH as major products. Electrons focused and amplified by photo systems I and II undergo a series of oxidation-reduction reactions as part of their electron transport chains. The Calvin cycle then takes products from the light reactions and uses it to make carbohydrate. During what photosynthetic process is rubisco active?
   Choose Answer
Do you have the necessary information to dissect the problem?
        · The light reactions of photosynthesis capture photons from sunlight using chlorophyll embedded in photosystems I and II and use that energy to establish a proton gradient, produce ATP, and reduce NADP+ to NADPH. These products are then used to fix inorganic carbon into organic form during the Calvin cycle.
        · The key enzyme involved in carbon fixation is rubisco. Since carbon fixation occurs during the Calvin cycle, no answers that involve products from the light reactions are plausible. That means making ATP, harvesting photons, making oxygen, and producing NADPH are infeasible answers. Therefore, the likely outcome of a rubisco enzyme mutation would be an inability to fix carbon and produce carbohydrate.

  Reflect on Process
Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        · Answering this question correctly depended on your ability to analyze the possible photosynthetic effect of a mutation in the rubisco enzyme.         · If you got a correct answer, well done! If you got an incorrect answer, did you recall that carbon fixation occurs during the Calvin cycle? Did you remember that the key enzyme that fixes carbon is rubisco? Were you able to infer that mutations in rubisco would affect carbon fixation?