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9th grade Light reactions and the Calvin cycle worksheet

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Light reactions and the Calvin cycle

Grade 9 Science Worksheet - Building Confidence

NameDate

Circle the best answer.

  1. Read this first

    Use this

    Chloroplast cutaway (model, not to scale).

  2. Ari studies a chloroplast drawing. Part A is a stack of flat, disc-shaped thylakoids. What is A called?

    • The thylakoid lumen
    • The granum
    • The stroma
    • The outer membrane

  3. Bo studies a chloroplast drawing. Part D is the liquid-filled space around the stacks of thylakoids. What is D?

    • The thylakoid membrane
    • The stoma
    • The granum
    • The stroma

  4. Esme wants to find the chlorophyll that absorbs light in a chloroplast. Which part holds it?

    • The outer membrane
    • The fluid inside each thylakoid
    • The stroma
    • The thylakoid membranes

  5. “model, not to scale” Jun reads that chlorophyll absorbs light and its energy is stored in ATP and NADPH. Which stage is this?

    • Fermentation
    • The Calvin cycle
    • The light reactions
    • Glycolysis

  6. Use this

    Flow diagram (model, not to scale), drawn inside a chloroplast. The name of the stage in box B is not shown.

  7. Kira reads that carbon dioxide is built into sugar (G3P) using ATP and NADPH. Which stage is this?

    • The light reactions
    • The Calvin cycle
    • The citric acid cycle
    • Cellular respiration

  8. Luz reads that water is split and oxygen is released. Which stage does this?

    • The Calvin cycle
    • Cellular respiration
    • The light reactions
    • Electron transport in a mitochondrion

  9. Use this

    Flow diagram (model, not to scale), drawn inside a chloroplast. In the thylakoid membranes: water and a wavy arrow of light energy go in; oxygen comes out. In the stroma: carbon dioxide goes in; G3P comes out. Arrow B runs from the stroma back to the thylakoid membranes. What it carries is not shown.

  10. Noah reads a chloroplast diagram. Arrow B runs from the stroma back to the thylakoid membranes. What does B carry?

    • ATP and NADPH
    • Nothing, since ATP and NADPH are used up for good
    • G3P, made by the light reactions
    • ADP, Pi and NADP+

  11. Flow diagram (model, not to scale). Pia reads a chloroplast diagram. Arrow C leaves the thylakoid membranes and carries a gas out of the chloroplast. What does C carry, and where does it come from?

    • Oxygen, made from carbon dioxide
    • Hydrogen gas, made from split water
    • Carbon dioxide, left over from split water
    • Oxygen, made from split water

  12. The name of the sugar and the zone that builds it are not shown. Ren fills in box D, the sugar that leaves the chloroplast. What goes in D, and where is it built?

    • ATP, built in the stroma
    • G3P, built in the stroma
    • G3P, built in the thylakoid membranes
    • ATP, built in the thylakoid membranes

  13. Use this

    Flow diagram (model, not to scale), drawn inside a chloroplast. In the stroma: NADPH goes in and is spent. Box E is an output box in the stroma. An arrow carries box E back to the thylakoid membranes. The name in box E is not shown.

  14. Zee fills in box E, made when the Calvin cycle spends NADPH. What goes in E?

    • Carbon dioxide
    • Nothing: the spent NADPH just disappears
    • NADPH
    • NADP+
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9th grade Light reactions and the Calvin cycle worksheet – printable
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About this worksheet

Light reactions and the Calvin cycle. Every version has 10 questions, and the answer key prints on the second page.

What your child will learn

  • I can name the parts of a chloroplast that matter here: the thylakoid membranes (with chlorophyll), the stacks called grana, and the stroma around them.
  • I can say what the light reactions do (chlorophyll absorbs light, water is split, oxygen is released, ATP and NADPH are made) and where (the thylakoid membranes).
  • I can say what the Calvin cycle does (it spends ATP and NADPH to fix carbon dioxide into the sugar G3P) and where (the stroma), and I can name its three stages: fixation, reduction and regeneration.
  • I can follow the carriers: ATP and NADPH go from the thylakoid membranes to the stroma, and ADP, Pi and NADP+ come back to be refilled.
  • I can use the counts that the book states: 3 turns of the cycle for one G3P to leave, 6 turns for one glucose, 6 ATP and 6 NADPH in the reduction stage and 3 more ATP in regeneration for 3 turns, 2 split waters for each O2.
  • I can read a model-data card to predict what happens when the light goes off, when the light color changes, or when carbon dioxide runs short, and I can say why the Calvin cycle is no longer called the dark reactions.

Standard: HS-LS1-5

Words to know

chloroplast: The plant-cell part where photosynthesis happens; it has two membranes around it

thylakoid: A flat, disc-shaped sac inside the chloroplast; its membrane holds chlorophyll

granum (plural grana): A stack of thylakoids

stroma: The liquid that fills the chloroplast around the stacks

chlorophyll: The green pigment that absorbs light, mainly blue and red

light reactions (light-dependent reactions): Stage 1: light is absorbed, water is split, ATP and NADPH are made

Calvin cycle (light-independent reactions): Stage 2: ATP and NADPH are spent to build sugar from carbon dioxide

ATP, NADPH: The two energy carriers the light reactions fill and the Calvin cycle spends

Common mistakes

Your child thought the Calvin cycle (once called the dark reactions) runs on its own at night, with no help from light. It spends ATP and NADPH made by the light reactions. Ask your child what the Calvin cycle spends.

Your child put a stage in the wrong part of the chloroplast. The light reactions happen in the thylakoid membranes; the Calvin cycle happens in the stroma. Ask your child to point to each on a drawing.

Your child thought the oxygen comes from carbon dioxide or from the Calvin cycle. It comes from water split in the light reactions. Ask your child which molecule is split to release oxygen.

Questions parents ask

What is the most common mistake with light reactions and the calvin cycle?

Your child thought the Calvin cycle (once called the dark reactions) runs on its own at night, with no help from light. It spends ATP and NADPH made by the light reactions. Ask your child what the Calvin cycle spends.

Are these 9th grade science worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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