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Science lesson plan · 11th grade (Year 12 in England) · 45 minutes

Light-dependent reactions and the Calvin cycle

Plants

CCSS NGSS.HS-LS1-5England: A level Biology: Photosynthesis (extension)

Objective and success criteria

Students will: Light-dependent reactions and the Calvin cycle.

  • I can answer questions on today's skill on my own, without help.
  • I can explain each step and say why it works.
  • I can check my answer and spot a mistake.

Before and after

Needs first: Photosynthesis: word and balanced symbol equations

Leads to: the next skill in this area.

Materials: Real plants or seeds, Hand lenses, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).

Warm-up · 5 min

  • Quick retrieval from earlier learning (Photosynthesis: word and balanced symbol equations). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. Which is the balanced symbol equation for photosynthesis? (CO₂ + H₂O → C₆H₁₂O₆ + O₂ / 6CO₂ + 6H₂O → C₆H₁₂O₆ + 3O₂ / C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O / 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂) → 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂Prompt: Carbon dioxide and water are the reactants.
  2. A leaf makes 5 molecules of glucose by photosynthesis. Using 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂, how many water molecules are used? → 30Prompt: Read the numbers in front of each formula.
  3. Is photosynthesis exothermic or endothermic? (endothermic: energy is transferred from light to the chemical store in glucose / exothermic: it releases oxygen / neither / exothermic: it releases heat) → endothermic: energy is transferred from light to the chemical store in glucosePrompt: The plant must absorb energy to make glucose.

Hook · 5 min

  • Bring in a plant that has been kept in the dark next to one in the light, and ask what happened.
  • Share the objective: Light-dependent reactions and the Calvin cycle. Read the success criteria together.

I do: model it · 10 min

  • Work through the example out loud, saying why you do each step, not just what you do.
  • Example: Which stage of photosynthesis: fixes carbon dioxide with the enzyme RuBisCO?
  • Step 1: The Calvin cycle in the stroma fixes carbon dioxide using ATP and NADPH to make sugars.
  • Step 2: So the answer is: Calvin cycle (light-independent)
  • Answer: Calvin cycle (light-independent)
  • Pause after each step and ask a student to say what comes next.

We do: guided practice · 10 min

  • Do these together. Students try each step on whiteboards before you reveal it.
  • Use the hints as prompts rather than giving the answer.
  1. Which stage of photosynthesis: make ATP and NADPH? (light-dependent reactions / Calvin cycle (light-independent)) → light-dependent reactionsPrompt: Which stage needs carbon dioxide and which needs light energy directly?
  2. Scientists gave algae water containing a heavy oxygen isotope (¹⁸O). Where did the ¹⁸O end up? (in the glucose made / in the carbon dioxide absorbed / in the chlorophyll / in the oxygen gas released) → in the oxygen gas releasedPrompt: Which reactant is split in the light-dependent reactions?

You do: independent practice · 10 min

  • Students work on the student sheet. Circulate and check the first two answers of every student early.
  • Students who finish: write a question of their own for a partner, with the answer.

The 8 questions are on the student sheet below, with answers in the key.

Exit ticket · 5 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. Stages of photosynthesis: which statement is NOT true? (Chlorophyll is found in the thylakoid membranes. / The light-dependent reactions release oxygen. / Carbon dioxide is split to release oxygen. / The Calvin cycle uses ATP and NADPH.) → Carbon dioxide is split to release oxygen.Prompt: Which molecule is split to release oxygen?
  2. A plant is moved into darkness. Why does the Calvin cycle soon stop, even though it does not use light directly? (The stroma freezes / Carbon dioxide disappears in the dark / It runs out of ATP and NADPH from the light-dependent reactions / RuBisCO is destroyed by darkness) → It runs out of ATP and NADPH from the light-dependent reactionsPrompt: What does the Calvin cycle need from the first stage?

Watch out for

  • Everyday meanings of words getting in the way of the science meaning: define key words explicitly.
  • Remembering facts without the reason: ask "why?" and "what is the evidence?"

Support and stretch

Support

  • Review first: Photosynthesis: word and balanced symbol equations.
  • Use concrete materials: real plants or seeds.
  • Give the first step of each question, or a partly worked example to finish.
  • Pair with a confident partner for the guided practice.

Stretch

  • Explain a common mistake in writing and how to fix it.
  • Write a word problem that uses today's skill, then solve a partner's.

Homework and more practice

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-11.

Free lesson plan from eurekami.com/lesson-plan-builder

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Light-dependent reactions and the Calvin cycle

Name

Date

Score/ 8

  1. Question 1

    Stages of photosynthesis: which statement is NOT true?

    • A. Chlorophyll is found in the thylakoid membranes.
    • B. The light-dependent reactions make glucose directly.
    • C. The Calvin cycle takes place in the stroma.
    • D. The Calvin cycle uses ATP and NADPH.

  2. Question 2

    Which stage of photosynthesis: fixes carbon dioxide with the enzyme RuBisCO?

    • A. light-dependent reactions
    • B. Calvin cycle (light-independent)

  3. Question 3

    Scientists gave algae water containing a heavy oxygen isotope (¹⁸O). Where did the ¹⁸O end up?

    • A. in the glucose made
    • B. in the oxygen gas released
    • C. in the carbon dioxide absorbed
    • D. in the chlorophyll

  4. Question 4

    Which stage of photosynthesis: uses ATP and NADPH to make sugar?

    • A. light-dependent reactions
    • B. Calvin cycle (light-independent)

  5. Question 5

    Where in the chloroplast is chlorophyll found?

    • A. in the outer membrane only
    • B. in the stroma
    • C. in the thylakoid membranes
    • D. in starch grains

  6. Question 6

    Which stage of photosynthesis: make ATP and NADPH?

    • A. light-dependent reactions
    • B. Calvin cycle (light-independent)

  7. Question 7

    A plant is moved into darkness. Why does the Calvin cycle soon stop, even though it does not use light directly?

    • A. RuBisCO is destroyed by darkness
    • B. It runs out of ATP and NADPH from the light-dependent reactions
    • C. Carbon dioxide disappears in the dark
    • D. The stroma freezes

  8. Question 8

    RuBisCO is often called the most abundant protein on Earth. What does it do?

    • A. splits water
    • B. fixes carbon dioxide into organic molecules
    • C. absorbs light
    • D. makes oxygen

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Answer key: Light-dependent reactions and the Calvin cycle

  1. 1. B. The light-dependent reactions make glucose directly.

  2. 2. B. Calvin cycle (light-independent)

  3. 3. B. in the oxygen gas released

  4. 4. B. Calvin cycle (light-independent)

  5. 5. C. in the thylakoid membranes

  6. 6. A. light-dependent reactions

  7. 7. B. It runs out of ATP and NADPH from the light-dependent reactions

  8. 8. B. fixes carbon dioxide into organic molecules