Lesson 3

Lesson 3: Respiration & ATP

How Living Things Release Energy from Food

🍞🩸🫀⚡🔋

Learning Objectives:

2.34 – Understand that the energy for life processes is released by respiration.
2.35 – Know that ATP is the energy currency of cells, produced during respiration.

🏆 By the end I will be able to…

All: state the word equation for aerobic respiration and say what ATP is.

Most: explain why respiration is not breathing and where it happens.

Some: link respiration to the whole digestive journey and justify "energy currency".

Navigation: Arrow Keys or Spacebar

Teacher Print Tools – Lesson 3

⭐ Fab 4

The Fab 4 – Recall to Get You Started

Instructions: Answer in your books from memory. Q1–3 recall previous lessons. Q4 leads into today.

⭐ The Fab 4 — Quick-Fire Recall

Four to warm up the brain — try all of the Fab 4 before the teacher reveals answers. Keeps knowledge "sticky"!

1. Name the enzyme that breaks starch → maltose

Amylase

2. Where is bile produced?

Liver

3. What is the function of villi?

Absorb digested food

4. Name one villi adaptation

Large SA / thin walls / blood supply

1. Enzymes (Recall)

Name the enzyme that breaks starch into maltose.

Amylase.

2. Absorption (Recall)

In which part of the small intestine is digested food absorbed into the blood?

The ileum.

3. Villi (Recall)

Name two adaptations of villi that help absorption.

Any two: large surface area, microvilli, one cell thick, good blood supply, lacteals.

4. Lead-in: Energy

Once glucose has been absorbed into the blood, what do you think cells use it for?

To release energy (through respiration).

1. Enzymes (Recall)

Complete: Starch → ______ by amylase → ______ by maltase.

Maltose, then glucose.

2. Bile (Recall)

Explain the two roles of bile in digestion.

1) Neutralises stomach acid for alkaline conditions. 2) Emulsifies fats, increasing SA:V for lipase.

3. Absorption (Recall)

Explain why villi being one cell thick helps absorption.

Short diffusion pathway, so nutrients cross into the blood quickly.

4. Lead-in: Energy

Glucose is absorbed into the blood and carried to every cell. What chemical process do cells use to release the energy stored in glucose?

Respiration.

1. Enzymes (Recall)

Explain why the digestion of starch requires two separate enzymes (amylase and maltase).

Amylase breaks starch (polysaccharide) to maltose (disaccharide). Maltase breaks maltose to glucose (monosaccharide). Each enzyme is specific to one substrate.

2. Absorption (Recall)

Explain how the blood supply in a villus maintains a steep concentration gradient for absorption.

Blood constantly carries absorbed nutrients away from the ileum wall, keeping the concentration in the blood low relative to the gut, so diffusion continues rapidly.

3. Bile (Recall)

Explain how emulsification increases the rate of lipid digestion. Use the term SA:V.

Emulsification breaks large fat droplets into smaller ones, increasing SA:V. More surface area for lipase to bind to, so more fat digested per second.

4. Lead-in: Energy

Glucose contains chemical energy stored in its bonds. Suggest why cells need a controlled chemical process to release this energy rather than simply burning it.

Burning releases all energy as heat at once, which would damage cells. Respiration releases energy in small, controlled steps so cells can use it for specific processes without overheating.

Starter

Starter: Tick Everything That Needs Energy

Instructions: On your printed sheet, tick ✅ every activity that needs energy. Cross ❌ anything that doesn't. No writing!

🏃 Running

💤 Sleeping

💭 Thinking

🌱 A plant growing

🧾 A dead leaf

🫀 Heart beating

🪨 A rock

🦠 Bacteria dividing

🥹 Shivering when cold

🧠 Big Question: Where does all that energy come from? 🔋 That's what today's lesson is about!

I Do

I Do: Aerobic Respiration (Spec 2.34)

Key Idea: Respiration is the process by which all living organisms release energy from glucose to produce ATP.

0/2

The Word Equation

Glucose + Oxygen → Carbon Dioxide + Water + ATP

The Symbol Equation

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP

Where does it happen?

Mostly in the mitochondria – the "powerhouses" of the cell.

Cells that need lots of energy (e.g. muscle cells) have more mitochondria.

Key Facts to Remember

✅ Happens in ALL living cells (animals, plants, fungi, bacteria).

✅ Happens all the time – 24 hours a day.

✅ Aerobic respiration needs oxygen.

✅ Glucose comes from the food we digest and absorb.

✅ Oxygen comes from the air we breathe into our lungs.

The Journey So Far

Food → Digested → Absorbed → Respired in cells → ATP (energy)

The Mitochondria

🧠 Memory Trick: "Mighty Mitochondria Make ATP" – Mitochondria are the powerhouse of the cell. More mitochondria = more ATP = more energy!

Aspire: Why do muscle cells have MORE mitochondria than skin cells?

Don't write: "Oxygen makes energy." or "Respiration makes energy."

Write: "Glucose and oxygen react to release energy as ATP."

Energy is released, not made — you can't create energy (Conservation of Energy). Always say ATP.

Talk to your partner: In your own words, what are the two things going IN and the three things coming OUT of respiration? Be ready to build it next.

We Do

We Do: Build the Aerobic Respiration Equation

Instructions: Drag each tile into the right space to build the word equation. Reactants feed into the mitochondrion; products come out. (Works by touch or mouse.)

Tiles placed: 0/5

Tile bank — drag each into the right place:

Carbon Dioxide

ATP (energy)

Glucose

Water

Oxygen

Reactants (IN)

fuel
(sugar)

the gas
breathed in

→

Products (OUT)

waste
gas

liquid

energy
(last!)

🧡 Tip: Reactants (what goes IN) on the LEFT. Products (what comes OUT) on the RIGHT. ATP always comes out LAST.

Start with the fuel: Glucose goes first, then the gas it reacts with (Oxygen). The waste gas (Carbon Dioxide) and Water come out, and ATP is always last.

I Do

I Do: ATP – The Energy Currency (Spec 2.35)

Key Idea: ATP (adenosine triphosphate) is the molecule that provides energy for cells. Think of it as the body's rechargeable battery.

0/2

What is ATP?

Adenosine Triphosphate – a small molecule that stores and carries energy.

It is produced by respiration in the mitochondria.

When a cell needs energy, it breaks down ATP to release it.

ATP is the cell's rechargeable battery — respiration tops it up, cell work drains it.

⚠️ Respiration ≠ Breathing

Respiration = chemical reaction inside cells (makes ATP).

Breathing (ventilation) = moving air in/out of lungs.

Breathing delivers the oxygen that respiration needs, but they are different processes!

What does ATP provide energy for?

💪

Muscle contraction

Movement

🔄

Active transport

Moving molecules against gradient

🧬

Cell division

Growth & repair

🔧

Protein synthesis

Building new proteins

⚡

Nerve impulses

Sending signals

🌡️

Body temperature

Maintaining warmth

Aspire: A sperm cell is packed with mitochondria around its tail. Suggest why.

💡 Real-World Link: When you shiver in the cold, that's ATP powering muscle contractions to generate heat. When your heart beats, that's ATP. When you think, that's ATP powering nerve impulses. Every second, your body uses and regenerates about 10 million ATP molecules!

Examiners love this phrase: "Respiration releases energy from glucose to make ATP, which cells use for processes like..."

Three examples of ATP use = more marks: muscle contraction, active transport, protein synthesis, cell division.

Talk to your partner: Name three things in your body using ATP right now. Next we'll sort which processes need it and which don't.

We Do

We Do: Does It Use ATP?

Instructions: Drag each process card into the right bin. Does it need ATP energy to happen? (Works by touch or mouse.)

Sorted: 0/6

💪 Muscle contraction

🌬️ Breathing in (ventilation)

🔄 Active transport

🧬 Cell division

🫧 Diffusion

⚡ Nerve impulses

✅ Uses ATP

Active — needs energy

❌ Does NOT use ATP

Passive — happens on its own

Ask: "does this need energy to happen?" Active processes (transport against a gradient, contracting, dividing, firing nerves) use ATP. Passive processes like diffusion happen on their own — no ATP.

Independent Work

Independent Work – Respiration & ATP

Instructions: Complete your printed worksheet at your level. You may use your definitions from the starter and the knowledge organiser.

Independent Work Timer

08:00

Foundation (Grades U–1)

MCQ + short answer on the word equation, ATP, and where respiration occurs.

Middle (Grades 2–3)

Short answer, equation completion, and a 4-mark exam question on ATP uses.

Higher (Grades 3–5)

Extended response including a 5-mark question linking respiration to cell function.

📋 Scaffolding

Your pack includes the respiration equation, ATP uses diagram, key word glossary, and a respiration vs breathing comparison.

🏆 Success Criteria

Foundation (U–1): I can state the word equation for aerobic respiration, say what ATP is, and name two uses of ATP.

Middle (2–3): I can write the symbol equation, explain why respiration is not breathing, and describe three uses of ATP in cells.

Higher (3–5): I can explain why muscle cells have more mitochondria, link respiration to the whole digestive pathway, and evaluate why ATP is called the "energy currency".

Exit Ticket

Exit Ticket – Respiration & ATP

Knowledge check: Tap your answer to each question — you'll get instant feedback and a score at the end. Books closed, no notes!

Score: 0/6

🖨️ Print written exit ticket:

Knowledge Organiser (L3): Respiration & ATP

Concept	Details
Respiration	Chemical reaction in ALL living cells releasing energy from glucose to produce ATP.
Aerobic	Respiration using oxygen. Produces the most ATP.
Word equation	Glucose + Oxygen → Carbon Dioxide + Water + ATP
Symbol equation	C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP
ATP	Adenosine triphosphate – molecule that provides energy for cells.
Mitochondria	Organelle where respiration occurs. "Powerhouse of the cell."
ATP uses	Muscle contraction, active transport, cell division, protein synthesis, nerve impulses, body temperature.
Respiration ≠ Breathing	Respiration = chemical reaction in cells. Breathing = ventilation (air in/out of lungs).
Who respires?	ALL living organisms: animals, plants, fungi, bacteria. 24 hours a day.

The Fab 4 – Recall Starter

Foundation

1) Name the enzyme that breaks starch into maltose.

2) In which part of the small intestine is food absorbed?

3) Name two adaptations of villi.

4) Once glucose is absorbed, what do cells use it for?

Middle

1) Complete: Starch → _____ (amylase) → _____ (maltase).

2) Explain the two roles of bile.

3) Why does being one cell thick help villi?

4) What chemical process releases energy from glucose?

Higher

1) Explain why starch digestion needs two enzymes.

2) How does blood supply maintain a steep concentration gradient in villi?

3) How does emulsification increase digestion rate? Use SA:V.

4) Why do cells need a controlled process to release energy?

Lesson 3 Starter: Tick Everything That Needs Energy

Instructions: Put a ✅ next to anything that needs energy. Put a ❌ next to anything that doesn't.

✅ or ❌	Activity
	Running
	Sleeping
	Thinking
	A plant growing
	A dead leaf
	Heart beating
	A rock
	Bacteria dividing
	Shivering when cold

Big Question: Where does all this energy come from?

Scaffolding Sheet – Middle (Grades 2–3)

Equations

Word: Glucose + Oxygen → Carbon Dioxide + Water

Symbol: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

Key Words

Respiration	Chemical reaction releasing energy from glucose.
ATP	Adenosine triphosphate – energy molecule.
Mitochondria	Organelle where respiration occurs.
Aerobic	With oxygen.

Scaffolding Sheet – Higher (Grades 3–5)

Key Terms

ATP, mitochondria, aerobic, glucose, oxygen, carbon dioxide, ventilation, cell division, active transport, protein synthesis

Independent Work – Foundation (Grades U–1)

Part A: Multiple Choice (circle the correct answer)

1) What is respiration? A) Breathing in and out B) A chemical reaction in cells C) Digesting food D) Pumping blood

2) What does ATP stand for? A) Amino tri-protein B) Adenosine triphosphate C) Active transport process D) Acid tri-phosphate

3) Where does respiration mainly occur? A) Lungs B) Stomach C) Mitochondria D) Brain

4) Which gas is needed for aerobic respiration? A) Carbon dioxide B) Nitrogen C) Oxygen D) Hydrogen

Part B: Short Answer

5) Write the word equation for aerobic respiration.

6) Name two things ATP provides energy for.

7) Do plants respire? Explain.

Part C: Long Answer

8) Explain why respiration is NOT the same as breathing. Describe what each one is and where it happens.

Part D: Exam Question [3 marks]

9) Describe three processes in the body that require energy from ATP. [3]

Independent Work – Middle (Grades 2–3)

Part A: Multiple Choice

1) Respiration occurs in: A) Only animals B) Only plants C) All living organisms D) Only mammals

2) The organelle where respiration occurs: A) Nucleus B) Cell membrane C) Mitochondria D) Ribosome

3) ATP provides energy for: A) Digestion only B) Cell processes like muscle contraction C) Breathing only D) Photosynthesis

Part B: Short Answer

4) Write the symbol equation for aerobic respiration.

5) Explain the difference between respiration and breathing.

6) Name four processes that require ATP.

Part C: Long Answer

7) Explain why muscle cells have more mitochondria than skin cells. Link this to ATP production and energy demand.

Part D: Exam Question [4 marks]

8) A student says "plants don't respire because they photosynthesise." Explain why this statement is incorrect. [4]

Independent Work – Higher (Grades 3–5)

Part A: Multiple Choice

1) ATP is described as the "energy currency" because: A) It costs money B) It is a universal energy carrier for all cell processes C) It only works in muscles D) It is made of gold

2) Which is NOT a use of ATP? A) Active transport B) Diffusion C) Protein synthesis D) Nerve impulses

Part B: Short Answer

3) Explain why ATP is described as the "energy currency" of cells.

4) Explain why cells that carry out active transport need many mitochondria.

Part C: Long Answer

5) Explain why all living organisms must respire continuously, even when they are not moving.

Part D: Exam Question [5 marks]

6) Trace the journey of a starch molecule from bread to the production of ATP in a muscle cell. Include digestion, absorption, and respiration. [5]

Exit Ticket – Respiration & ATP (Foundation U–1)

Name: ______________________ Class: __________ Date: __________

Answer from memory — no notes.

1) Write the word equation for aerobic respiration.

2) Which gas is needed for aerobic respiration?

3) In which organelle does respiration mostly happen?

4) What does ATP stand for?

5) Name two things ATP provides energy for.

6) Do plants respire? Circle: YES / NO

Exit Ticket – Respiration & ATP (Middle 2–3)

Name: ______________________ Class: __________ Date: __________

Answer from memory — no notes.

1) Write the symbol equation for aerobic respiration.

2) Name the three products of aerobic respiration.

3) Explain the difference between respiration and breathing.

4) Why do muscle cells have more mitochondria than skin cells?

5) Name three processes that use ATP.

6) What is ATP and where is it produced?

Exit Ticket – Respiration & ATP (Higher 3–5)

Name: ______________________ Class: __________ Date: __________

Answer from memory — no notes.

1) Why is ATP called the "energy currency" of the cell?

2) Why do we say energy is "released", not "made", in respiration?

3) A student says "plants don't respire." Explain why this is wrong.

4) Why must respiration happen all the time, even when resting?

5) Explain why active transport needs cells with many mitochondria.

6) A sperm cell has many mitochondria packed around its tail. Suggest why.

Lesson 3: Respiration & ATP

🏆 By the end I will be able to…

Teacher Print Tools – Lesson 3

The Fab 4 – Recall to Get You Started

⭐ The Fab 4 — Quick-Fire Recall

1. Enzymes (Recall)

2. Absorption (Recall)

3. Villi (Recall)

4. Lead-in: Energy

1. Enzymes (Recall)

2. Bile (Recall)

3. Absorption (Recall)

4. Lead-in: Energy

1. Enzymes (Recall)

2. Absorption (Recall)

3. Bile (Recall)

4. Lead-in: Energy

Starter: Tick Everything That Needs Energy

I Do: Aerobic Respiration (Spec 2.34)

The Word Equation

The Symbol Equation

Where does it happen?

Key Facts to Remember

The Journey So Far

The Mitochondria

We Do: Build the Aerobic Respiration Equation

I Do: ATP – The Energy Currency (Spec 2.35)

What is ATP?

⚠️ Respiration ≠ Breathing

What does ATP provide energy for?

We Do: Does It Use ATP?

✅ Uses ATP

❌ Does NOT use ATP

Independent Work – Respiration & ATP

Foundation (Grades U–1)

Middle (Grades 2–3)

Higher (Grades 3–5)

📋 Scaffolding

🏆 Success Criteria

Exit Ticket – Respiration & ATP

Knowledge Organiser (L3): Respiration & ATP

The Fab 4 – Recall Starter

Foundation

Middle

Higher

Lesson 3 Starter: Tick Everything That Needs Energy

Scaffolding Sheet – Middle (Grades 2–3)

Equations

Key Words

Scaffolding Sheet – Higher (Grades 3–5)

Key Terms

Independent Work – Foundation (Grades U–1)

Independent Work – Middle (Grades 2–3)

Independent Work – Higher (Grades 3–5)

Exit Ticket – Respiration & ATP (Foundation U–1)

Exit Ticket – Respiration & ATP (Middle 2–3)

Exit Ticket – Respiration & ATP (Higher 3–5)

We Do – Class Evidence

🎓 TA Focus

🎯 Cold Call

📺 Aerobic Respiration & ATP

🏆 Class Progress Board

🎉 Lesson Complete!