Back to the lesson plan builder
Lesson length30 min45 min60 min
Questions🔀 New questions

Print the plan for yourself; the student sheet prints on its own page after it.

Science lesson plan · 9th grade (Year 10 in England) · 45 minutes

How enzymes work: active sites, temperature and pH

Cells, genetics and evolution

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

Objective and success criteria

Students will: How enzymes work: active sites, temperature and pH.

  • 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: Digestive enzymes and the molecules they make

Leads to: Work out enzyme reaction rates from experimental data

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

Warm-up · 5 min

  • Quick retrieval from earlier learning (Digestive enzymes and the molecules they make). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. Which enzyme is described here: breaks proteins down into amino acids? (amylase (a carbohydrase) / protease / lipase) → proteasePrompt: The enzyme's name often sounds like the food it breaks down.
  2. Amylase was mixed with starch at different temperatures. Iodine was used to time how long the starch took to disappear: 20 °C: 8 min 30 °C: 3 min 40 °C: 9 min 50 °C: 9 min 60 °C: starch still present after 20 min At which temperature did amylase work fastest, in °C? → 30 °CPrompt: Fastest means the shortest time.
  3. What does bile do in digestion? (turns starch into sugar / absorbs water / breaks fat into small droplets and neutralises stomach acid / digests protein into amino acids) → breaks fat into small droplets and neutralises stomach acidPrompt: Bile is not an enzyme.

Hook · 5 min

  • Show a microscope image of cells and ask what students think they are looking at.
  • Share the objective: How enzymes work: active sites, temperature and pH. 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: Why does a reaction speed up as temperature rises towards the optimum?
  • Step 1: More kinetic energy means more successful collisions between enzyme and substrate.
  • Step 2: So the answer is: Molecules move faster, so enzyme and substrate collide more often
  • Answer: Molecules move faster, so enzyme and substrate collide more often
  • 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. Pepsin works best at pH 2. Where in the body does it work? (the blood / the stomach / the small intestine / the mouth) → the stomachPrompt: Which part of the gut is very acidic?
  2. Enzymes: which statement is NOT true? (Enzymes are not used up in the reactions they speed up. / Most human enzymes work best at about 37 °C. / Enzymes are living things. / Enzymes are proteins.) → Enzymes are living things.Prompt: Is the effect of cold permanent?

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. What happens to an enzyme above its optimum temperature? (It is killed like a cell / Its active site changes shape and it is denatured / It turns into a different enzyme / It works faster and faster forever) → Its active site changes shape and it is denaturedPrompt: Enzymes are proteins; heat breaks the bonds holding their shape.
  2. Enzymes: which statement is NOT true? (Enzymes are proteins. / Enzymes are biological catalysts. / Enzymes are not used up in the reactions they speed up. / All enzymes work best at pH 7.) → All enzymes work best at pH 7.Prompt: Is the effect of cold permanent?

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: Digestive enzymes and the molecules they make.
  • 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

  • Move on to: Work out enzyme reaction rates from experimental data.
  • 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

How enzymes work: active sites, temperature and pH

Name

Date

Score/ 8

  1. Question 1

    Enzymes: which statement is NOT true?

    • A. Cold temperatures denature enzymes permanently.
    • B. Enzymes are biological catalysts.
    • C. Most human enzymes work best at about 37 °C.
    • D. Enzymes are not used up in the reactions they speed up.

  2. Question 2

    A human enzyme has an optimum temperature of about 37 °C. What is the enzyme most likely to be doing at 15 °C?

    • A. working slowly, but not denatured
    • B. working at or near its fastest rate
    • C. denatured and no longer working

  3. Question 3

    Why does a reaction speed up as temperature rises towards the optimum?

    • A. The enzyme gets bigger
    • B. The substrate becomes an enzyme
    • C. Molecules move faster, so enzyme and substrate collide more often
    • D. The active site disappears

  4. Question 4

    A human enzyme has an optimum temperature of about 37 °C. What is the enzyme most likely to be doing at 10 °C?

    • A. working slowly, but not denatured
    • B. working at or near its fastest rate
    • C. denatured and no longer working

  5. Question 5

    What happens to an enzyme above its optimum temperature?

    • A. Its active site changes shape and it is denatured
    • B. It works faster and faster forever
    • C. It turns into a different enzyme
    • D. It is killed like a cell

  6. Question 6

    A human enzyme has an optimum temperature of about 37 °C. What is the enzyme most likely to be doing at 5 °C?

    • A. working slowly, but not denatured
    • B. working at or near its fastest rate
    • C. denatured and no longer working

  7. Question 7

    A human enzyme has an optimum temperature of about 37 °C. What is the enzyme most likely to be doing at 70 °C?

    • A. working slowly, but not denatured
    • B. working at or near its fastest rate
    • C. denatured and no longer working

  8. Question 8

    A human enzyme has an optimum temperature of about 37 °C. What is the enzyme most likely to be doing at 38 °C?

    • A. working slowly, but not denatured
    • B. working at or near its fastest rate
    • C. denatured and no longer working

Free from eurekami.com

for the adult only

Answer key: How enzymes work: active sites, temperature and pH

  1. 1. A. Cold temperatures denature enzymes permanently.

  2. 2. A. working slowly, but not denatured

  3. 3. C. Molecules move faster, so enzyme and substrate collide more often

  4. 4. A. working slowly, but not denatured

  5. 5. A. Its active site changes shape and it is denatured

  6. 6. A. working slowly, but not denatured

  7. 7. C. denatured and no longer working

  8. 8. B. working at or near its fastest rate