Free BioInteractive Calvin Cycle Questions and Answers — Questions and Answers
Question 1: What is the main purpose of the Calvin Cycle?
- Convert light energy into ATP
- Fix carbon dioxide into glucose (Correct answer)
- Split water molecules to release oxygen
- Produce NADPH
Correct answer: Fix carbon dioxide into glucose
The main purpose of the Calvin Cycle is to fix atmospheric carbon dioxide into organic sugar molecules, specifically glucose. This process utilizes the ATP and NADPH produced during the light-dependent reactions to convert inorganic carbon into a usable energy form for the plant.
Question 2: Where does the Calvin Cycle take place?
- Thylakoid membrane
- Mitochondria
- Stroma of the chloroplast (Correct answer)
- Cytoplasm
Correct answer: Stroma of the chloroplast
The Calvin Cycle, also known as the light-independent reactions, takes place in the stroma of the chloroplast. The stroma is the fluid-filled space surrounding the thylakoids, where the necessary enzymes and substrates for carbon fixation and sugar synthesis are located.
Question 3: What is the first step of the Calvin Cycle?
- Carbon fixation (Correct answer)
- Reduction phase
- Regeneration of RuBP
- ATP synthesis
Correct answer: Carbon fixation
The first step of the Calvin Cycle is carbon fixation, where the enzyme RuBisCO catalyzes the attachment of a carbon dioxide molecule to a five-carbon sugar, ribulose-1,5-bisphosphate (RuBP). This initiates the conversion of inorganic carbon into organic compounds.
Question 4: Which enzyme is responsible for fixing CO₂ in the Calvin Cycle?
- ATP synthase
- RuBisCO (Correct answer)
- NADP+ reductase
- Chlorophyll
Correct answer: RuBisCO
The enzyme responsible for fixing CO₂ in the Calvin Cycle is Ribulose-1,5-bisphosphate carboxylase/oxygenase, commonly known as RuBisCO. This enzyme catalyzes the crucial initial step where CO₂ combines with RuBP, initiating the synthesis of organic molecules.
Question 5: What molecule is regenerated at the end of the Calvin Cycle to allow the cycle to continue?
- Glucose
- Ribulose bisphosphate (RuBP) (Correct answer)
- ATP
- NADPH
Correct answer: Ribulose bisphosphate (RuBP)
At the end of the Calvin Cycle, after glucose has been produced, the remaining molecules are regenerated back into ribulose bisphosphate (RuBP). This regeneration is vital as it allows the cycle to continue by providing the acceptor molecule for new carbon dioxide molecules.
Free BioInteractive Calvin Cycle Questions and Answers
What is the main purpose of the Calvin Cycle?