Light reactions and the Calvin cycle

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. Read this first

   Use this

   Chloroplast cutaway (model, not to scale).

2. 1.

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

   • The granum
   • The thylakoid lumen
   • The outer membrane
   • The stroma
3. 2.

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

   • The stoma
   • The thylakoid membrane
   • The stroma
   • The granum
4. 3.

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

   • The stroma
   • The thylakoid membranes
   • The fluid inside each thylakoid
   • The outer membrane
5. 4.

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

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

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. 5.

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

   • The citric acid cycle
   • The Calvin cycle
   • Cellular respiration
   • The light reactions
8. 6.

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

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

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. 7.

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

    • Nothing, since ATP and NADPH are used up for good
    • ATP and NADPH
    • G3P, made by the light reactions
    • ADP, Pi and NADP+
11. 8.

    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?

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

12. Use this

    Flow diagram (model, not to scale), drawn inside a chloroplast. In the stroma: carbon dioxide goes in; G3P comes out. A label under the stroma box is blank. Arrows carry ATP and NADPH in from the thylakoid membranes, and ADP, Pi and NADP+ back.

13. 9.

    Tala fills in the blank label under the Calvin cycle box. When does the Calvin cycle make sugar?

    • When enough oxygen has built up in the stroma around it
    • When it is dark, since the cycle needs no help from light
    • When ATP and NADPH from the light reactions are available
    • When it sits in the thylakoid membranes beside the chlorophyll

14. 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.

15. 10.

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

    • NADP+
    • Carbon dioxide
    • Nothing: the spent NADPH just disappears
    • NADPH