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Science lesson plan · 9th grade (Year 10 in England) · 30 minutes

Work out enzyme reaction rates from experimental data

Cells, genetics and evolution

CCSS NGSS.HS-LS1-6CCSS NGSS.SEP 5England: GCSE Combined Science: Organisation (required practical: enzymes)

Objective and success criteria

Students will: Work out enzyme reaction rates from experimental data.

  • 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: How enzymes work: active sites, temperature and pH

Leads to: the next skill in this area.

Materials: Microscope images or slides, Cell diagrams, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).

Warm-up · 4 min

  • Quick retrieval from earlier learning (How enzymes work: active sites, temperature and pH). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. Why does a reaction speed up as temperature rises towards the optimum? (The enzyme gets bigger / The active site disappears / The substrate becomes an enzyme / Molecules move faster, so enzyme and substrate collide more often) → Molecules move faster, so enzyme and substrate collide more oftenPrompt: Think about kinetic energy.
  2. Enzymes: which statement is NOT true? (Enzymes are not used up in the reactions they speed up. / Enzymes are living things. / Most human enzymes work best at about 37 °C. / Enzymes are biological catalysts.) → Enzymes are living things.Prompt: Is the effect of cold permanent?
  3. A human enzyme has an optimum temperature of about 37 °C. What is the enzyme most likely to be doing at 37 °C? (working slowly, but not denatured / working at or near its fastest rate / denatured and no longer working) → working at or near its fastest ratePrompt: Cold slows molecules down; it does not change the active site's shape.

Hook · 3 min

  • Show a microscope image of cells and ask what students think they are looking at.
  • Share the objective: Work out enzyme reaction rates from experimental data. Read the success criteria together.

I do: model it · 7 min

  • Work through the example out loud, saying why you do each step, not just what you do.
  • Example: Catalase in liver broke down hydrogen peroxide and released 10 cm³ of oxygen in 20 s. What was the mean rate of reaction, in cm³/s?
  • Step 1: 10 ÷ 20 = 0.5
  • Step 2: So the answer is: 0.5 cm³/s
  • Answer: 0.5 cm³/s
  • Pause after each step and ask a student to say what comes next.

We do: guided practice · 6 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. Catalase in liver broke down hydrogen peroxide and released 30 cm³ of oxygen in 25 s. What was the mean rate of reaction, in cm³/s? → 1.2 cm³/sPrompt: rate = amount of product ÷ time
  2. Amylase took 100 s to digest all the starch at pH 7. Calculate the rate using rate = 1000 ÷ time, in s⁻¹. → 10 s⁻¹Prompt: Substitute the time into the formula.

You do: independent practice · 7 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 6 questions are on the student sheet below, with answers in the key.

Exit ticket · 3 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. Amylase took 50 s to digest all the starch at pH 7. Calculate the rate using rate = 1000 ÷ time, in s⁻¹. → 20 s⁻¹Prompt: Substitute the time into the formula.
  2. Catalase in liver broke down hydrogen peroxide and released 16 cm³ of oxygen in 20 s. What was the mean rate of reaction, in cm³/s? → 0.8 cm³/sPrompt: rate = amount of product ÷ time

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: How enzymes work: active sites, temperature and pH.
  • Use concrete materials: microscope images or slides.
  • 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-9.

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

eurekami

Work out enzyme reaction rates from experimental data

Name

Date

Score/ 6

  1. Question 1

    An enzyme was timed digesting the same amount of substrate at different pH values: pH 3: 153 s pH 5: 129 s pH 7: 91 s pH 9: 34 s pH 11: 87 s What is its optimum pH?

    Answer

  2. Question 2

    Amylase took 20 s to digest all the starch at pH 7. Calculate the rate using rate = 1000 ÷ time, in s⁻¹.

    Answers⁻¹

  3. Question 3

    Catalase in liver broke down hydrogen peroxide and released 36 cm³ of oxygen in 30 s. What was the mean rate of reaction, in cm³/s?

    Answercm³/s

  4. Question 4

    An enzyme was timed digesting the same amount of substrate at different pH values: pH 3: 137 s pH 5: 89 s pH 7: 39 s pH 9: 87 s pH 11: 141 s What is its optimum pH?

    Answer

  5. Question 5

    Catalase in liver broke down hydrogen peroxide and released 36 cm³ of oxygen in 60 s. What was the mean rate of reaction, in cm³/s?

    Answercm³/s

  6. Question 6

    An enzyme was timed digesting the same amount of substrate at different pH values: pH 3: 133 s pH 5: 89 s pH 7: 30 s pH 9: 87 s pH 11: 129 s What is its optimum pH?

    Answer

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Answer key: Work out enzyme reaction rates from experimental data

  1. 1. 9

  2. 2. 50 s⁻¹

  3. 3. 1.2 cm³/s

  4. 4. 7

  5. 5. 0.6 cm³/s

  6. 6. 7