50+ photosynthesis worksheets for 9th Grade on Quizizz | Free ... - Free Printable

Here’s the correct answer and explanation for each of the first 5 questions from your “Photosynthesis” quiz:

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1. What is the pigment in chloroplasts that performs photosynthesis?

✔ Correct Answer: A. Chlorophyll

Explanation:
Chlorophyll is the green pigment found in chloroplasts that absorbs light energy (mainly blue and red wavelengths) to drive the process of photosynthesis. It’s essential for converting light energy into chemical energy.

- *B. Chlorosynthesis* — Not a real term; likely a distractor.
- *C. Electron Transport* — A process, not a pigment.
- *D. ADP* — A molecule involved in energy transfer, not a pigment.

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2. The stacks of disks in the chloroplast are called:

✔ Correct Answer: A. Grana (singular: granum)

Explanation:
Inside the chloroplast, thylakoid membranes are stacked into structures called grana. These stacks increase the surface area for light absorption and contain the photosystems needed for the light-dependent reactions.

- *B. Lamellae* — Refers to the connecting membranes between grana, not the stacks themselves.
- *C. Thylakoid* — The individual disk-like membrane; grana are stacks of thylakoids.
- *D. Stroma* — The fluid-filled space surrounding the thylakoids.

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3. The interior space of the chloroplast is called:

✔ Correct Answer: D. Stroma

Explanation:
The stroma is the gel-like substance inside the chloroplast, surrounding the thylakoid membranes. It’s where the light-independent reactions (Calvin cycle) occur, using ATP and NADPH produced in the thylakoids to fix carbon dioxide into glucose.

- *A. Lamellae* — Connecting membranes.
- *B. Grana* — Stacks of thylakoids.
- *C. Thylakoids* — Membranous disks, not the interior space.

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4. Where does the light independent reaction take place?

✔ Correct Answer: C. Stroma

Explanation:
The light-independent reactions (also called the Calvin cycle) occur in the stroma. They do not require light directly but use the products of the light-dependent reactions (ATP and NADPH) to synthesize glucose from CO₂.

- *A. Thylakoid membrane* — Site of light-dependent reactions.
- *B. Matrix* — This term is used for mitochondria, not chloroplasts.
- *D. Cytoplasm* — Outside the chloroplast; not involved in photosynthesis.

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5. Which of the following equations represents the overall chemical reaction for photosynthesis?

✔ Correct Answer: C. 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Explanation:
This is the balanced chemical equation for photosynthesis:
> Carbon dioxide + Water → Glucose + Oxygen
*(in the presence of light and chlorophyll)*

Let’s check the options:

- *A. C₆H₁₂O₆ + 6H₂O → 6O₂ + 6O₂* — Incorrect; glucose is a product, not reactant. Also, 6O₂ + 6O₂ = 12O₂ — wrong stoichiometry.
- *B. 6O₂ + 6H₂O → C₆H₁₂O₆ + 6CO₂* — This is cellular respiration, reversed.
- *C. 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂* — ✔ Correct!
- *D. 6O₂ + 6H₂O → C₆H₁₂O₆ + 6O₂* — Nonsensical; O₂ on both sides cancels out, leaving H₂O → C₆H₁₂O₆ — impossible.

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✔ Summary of Answers:

1. A. Chlorophyll
2. A. Grana
3. D. Stroma
4. C. Stroma
5. C. 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Let me know if you’d like help with question #6 or the rest of the quiz!