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

   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

4. Use this

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

5. 3.

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

   • The citric acid cycle
   • The light reactions
   • Cellular respiration
   • The Calvin cycle
6. 4.

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

   • Electron transport in a mitochondrion
   • The light reactions
   • Cellular respiration
   • The Calvin cycle
7. 5.

   What it carries is not shown. Milo reads a chloroplast diagram. Arrow A runs from the thylakoid membranes to the stroma. What does A carry?

   • ATP and NADPH
   • ADP, Pi and NADP+
   • Oxygen and water
   • Nothing, since the Calvin cycle needs no help

8. 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.

9. 6.

   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
   • ADP, Pi and NADP+
   • ATP and NADPH
   • G3P, made by the light reactions
10. 7.

    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?

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

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

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

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