BiochemistryLesson 3 of 3 in the course Photosynthesis

Calvin Cycle Stages, Energy Use, and Photosynthesis Connections

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

The Calvin cycle uses energy captured during the light-dependent reactions to incorporate carbon dioxide into organic molecules and ultimately build carbohydrates. This lesson follows the cycle through its location, three stages, and energy requirements.

In plants, carbon dioxide enters a leaf through tiny openings called stomata. It diffuses through the leaf into mesophyll cells and reaches the stroma, the fluid-filled space inside a chloroplast. The Calvin cycle reactions occur in the stroma.

All flashcards

Where does the Calvin cycle occur in plant cells?
In the stroma, the fluid-filled region inside a chloroplast.
What is RuBP?
A five-carbon molecule that accepts CO₂ during carbon fixation.
What happens during the reduction stage of the Calvin cycle?
ATP and NADPH help convert 3-PGA into G3P; the molecules gain electrons.
How is G3P used in the Calvin cycle?
Some leaves the cycle and can contribute to carbohydrate production; the rest helps regenerate RuBP.
How do photosynthesis and aerobic cellular respiration relate overall?
Photosynthesis stores energy in carbohydrates; respiration releases energy from them, with matter exchanged between the processes.

Quiz questions

  1. When the unstable six-carbon product of carbon fixation splits, what forms?Answer: Two three-carbon molecules of 3-PGA.
  2. Where do photosynthetic prokaryotes such as cyanobacteria provide sites for photosynthetic machinery?Answer: In infoldings of the plasma membrane.
  3. Which statement correctly compares the overall inputs and outputs of photosynthesis and aerobic respiration?Answer: Photosynthesis uses CO₂ and water; respiration uses carbohydrate and oxygen.
  4. How much ATP and NADPH are used for six turns of the Calvin cycle?Answer: 18 ATP and 12 NADPH.
  5. What happens to G3P that remains in the Calvin cycle rather than leaving as net product?Answer: It is rearranged, with ATP, to regenerate RuBP.

Based on Concepts of Biology by Samantha Fowler, Rebecca Roush, James Wise (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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