2.29 – Understand the role of digestive enzymes: amylase & maltase (starch to glucose), proteases (proteins to amino acids), lipases (lipids to fatty acids & glycerol).
2.30 – Understand that bile is produced by the liver and stored in the gallbladder.
2.31 – Understand the role of bile in neutralising stomach acid and emulsifying lipids.
Navigation: Arrow Keys or Spacebar
Teacher Print Tools – Lesson 1
Arrival Task
Arrival Task – Recall from the Digestive System
Instructions: Answer in your books from memory. Q1–3 recall the Digestive System lesson. Q4 leads into today.
1. Organs (Recall)
Name the five main organs of the alimentary canal in the correct order.
Mouth, oesophagus, stomach, small intestine, large intestine.
2. Peristalsis (Recall)
What is the name for the wave of muscular contraction that pushes food through the gut?
Peristalsis.
3. Stomach (Recall)
Name the strong acid found in the stomach that kills bacteria.
Hydrochloric acid (HCl).
4. Lead-in: Enzymes
Food molecules like starch are too big to pass into our blood. What type of chemical helps break them into smaller pieces?
Enzymes.
1. Alimentary Canal (Recall)
Name the two parts of the small intestine and state one function of each.
Duodenum – finishes chemical digestion. Ileum – absorbs digested food into the blood.
2. Peristalsis (Recall)
Describe how peristalsis moves a bolus of food through the oesophagus.
Waves of muscular contraction squeeze behind the bolus, pushing it along towards the stomach.
3. Accessory Organs (Recall)
Name one accessory organ and state what it produces.
Pancreas – produces digestive enzymes. Or: liver – produces bile; salivary glands – produce saliva with amylase.
4. Lead-in: Enzymes
Large insoluble molecules cannot pass through the gut wall. What type of biological catalyst breaks them into smaller soluble molecules?
Enzymes.
1. Digestion Types (Recall)
Explain the difference between mechanical and chemical digestion and give one location where both occur.
Mechanical digestion physically breaks food into smaller pieces (e.g. chewing). Chemical digestion uses enzymes to break bonds. Both occur in the mouth.
2. Peristalsis (Recall)
Explain why peristalsis works even when someone eats upside down.
Peristalsis uses active muscular contractions to push the bolus. It does not rely on gravity.
3. Stomach pH (Recall)
The stomach has a pH of about 2. Suggest why enzymes from the small intestine would be destroyed there.
Intestinal enzymes have an alkaline optimum pH. Highly acidic conditions would denature them, changing the active site shape.
4. Lead-in: Enzymes
Large insoluble molecules must become smaller soluble molecules before absorption. Name the catalyst responsible and suggest why specificity matters.
Enzymes. Each has a unique active site fitting only one substrate (lock and key), so different enzymes are needed for different food groups.
Starter
Starter: Match the Words to the Meanings
Instructions: Copy each word into your books. Then choose the meaning you think fits best from the list. Two words on the list are wrong – they don’t match any of the key words!
Key Words to Copy:
1. Enzyme – \_\_\_\_\_\_\_\_
2. Substrate – \_\_\_\_\_\_\_\_
3. Product – \_\_\_\_\_\_\_\_
4. Bile – \_\_\_\_\_\_\_\_
5. Emulsification – \_\_\_\_\_\_\_\_
Possible Meanings (pick one for each):
A. A green-yellow liquid that helps break up fats
B. A chemical in cells that is always there
C. Breaking large fat droplets into many smaller ones
D. A biological “scissors” that cuts big molecules into small ones
E. The new molecule made after an enzyme has worked
F. The molecule the enzyme works on (it gets broken down)
G. The tube that carries food to the stomach
🧠 Hint: Think about enzymes like a pair of scissors. The scissors = enzyme. What goes IN the scissors? What comes OUT?
Extension: Write the correct answers in your books like this: 1. Enzyme = D. A biological “scissors”...
I Do
I Do: Digestive Enzymes (Spec 2.29)
Key Idea: Digestion breaks large, insoluble molecules into smaller, soluble ones so they can be absorbed into the blood.
1. Carbohydrases
Amylase breaks starch (polysaccharide) into maltose (disaccharide).
Maltase then breaks maltose into glucose (monosaccharide).
Made in: salivary glands (mouth) and pancreas.
2. Proteases
Proteases break proteins into amino acids.
Stomach makes pepsin. Pancreas makes trypsin.
3. Lipases
Lipases break lipids (fats) into fatty acids and glycerol.
Made in the pancreas, released into the small intestine.
📝 Now complete your table!
Fill in the blank columns using the information on this slide.
Aspire: Why can't amylase break down proteins? Each enzyme has a uniquely shaped active site – the lock and key model.
Don't write:"Enzymes digest food."
Write:"Enzymes break down large insoluble molecules into small soluble ones."
The examiner wants the reason digestion happens (small = can be absorbed), not just the word "digest"!
We Do
We Do: Enzyme Matching Game
Instructions: Select an enzyme, then tap the matching substrate → product card.
Matches: 0/4
Step 1: Select an enzyme
🧪 Amylase
🧪 Maltase
🧪 Protease
🧪 Lipase
Step 2: Tap the matching description
Lipids → Fatty acids & glycerol
Starch → Maltose
Proteins → Amino acids
Maltose → Glucose
I Do
I Do: Bile (Spec 2.30 & 2.31)
Key Idea: Bile is not an enzyme – it prepares conditions for enzymes to work.
Where does bile come from?
Produced in the liver. Stored in the gallbladder. Released into the small intestine.
Job 1: Neutralise Stomach Acid
Food from stomach is acidic. Bile is alkaline – it neutralises the acid, creating conditions intestinal enzymes need.
Job 2: Emulsify Lipids
Bile breaks large fat droplets into many smaller droplets. This increases SA:V so lipase works faster.
💡 Real-World Link: Washing-up liquid works exactly like bile – it breaks grease into tiny droplets (emulsification). That's why you can't wash oily plates with just water – you need something to increase the SA:V so water can get at the grease!
Grab the mark by using: "Bile emulsifies fats to increase surface areaso that lipase works faster."
Three marks in one sentence: the process, the effect, and the link word ("so that") showing WHY.
We Do
We Do: Bile Fact Sort
Instructions: Select a fact card, then place it in the correct category: what bile IS, Job 1, or Job 2.
Score: 0/6
Produced in the liver
Neutralises stomach acid
Breaks large fat droplets into smaller ones
Stored in the gallbladder
Creates alkaline pH for enzymes
Increases SA:V for lipase
💚 What Bile Is
Job 1: Neutralise
Job 2: Emulsify
Independent Work
Independent Work – Enzymes & Bile
Instructions: Complete your printed worksheet at your level. You may use your enzyme table and knowledge organiser.
Independent Work Timer
08:00
Foundation (Grades U–1)
MCQ + short answer on enzyme names, substrates, products, and bile facts.
Middle (Grades 2–3)
Short answer, sentence completion, and 4-mark exam questions on bile.
Higher (Grades 3–5)
Extended response and a 5-mark question on gallbladder removal.
📋 Scaffolding
Your pack includes a completed enzyme table, bile key facts, and key word glossary.
🏆 Success Criteria
Foundation (U–1): Name enzyme groups, state what bile does, recall key facts.
Middle (2–3): Explain two-step starch digestion, describe both roles of bile, link SA:V to rate.
Higher (3–5): Explain enzyme specificity, evaluate impact of gallbladder removal.
2) Name the protease from the stomach and pancreas.
Pepsin (stomach), trypsin (pancreas).
3) Explain why emulsification helps lipase.
Breaks large fat droplets into smaller ones, increasing SA:V so lipase has more surface to act on.
1) Explain why starch digestion needs two enzymes.
Amylase breaks starch to maltose. Maltase breaks maltose to glucose. Each enzyme is specific to one substrate.
2) Why must bile neutralise stomach acid?
Intestinal enzymes have alkaline optimum pH. Acid would denature them.
3) Predict the effect of gallbladder removal on fat digestion.
Less bile = less emulsification = lower SA:V = lipase works slower = fat digestion less efficient.
Lesson 2 of 2
Digestion & Absorption
Absorption & the Structure of Villi
Learning Objective:
2.32 – Understand how the small intestine is adapted for absorption, including the structure of a villus.
Navigation: Arrow Keys or Spacebar
Teacher Print Tools – Lesson 2
Arrival Task
Arrival Task – Recall from Last Week (Enzymes & Bile)
Instructions: Answer from memory. Q1–3 recall last week. Q4 leads into today.
1. Enzymes (Recall)
Name the enzyme that breaks starch into maltose.
Amylase.
2. Lipids (Recall)
What two products does lipase make from lipids?
Fatty acids and glycerol.
3. Bile (Recall)
Where is bile produced and where is it stored?
Produced in the liver. Stored in the gallbladder.
4. Lead-in: Absorption
Once food is digested into small molecules, where does it enter the blood?
The small intestine (specifically the ileum).
1. Enzymes (Recall)
Complete: Starch → ______ by amylase → ______ by maltase.
Maltose, then glucose.
2. Proteases (Recall)
Name the protease from the stomach and the one from the pancreas.
Pepsin (stomach), trypsin (pancreas).
3. 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.
4. Lead-in: Absorption
Digested food passes into the bloodstream. What is this process called, and in which part of the small intestine?
Absorption. In the ileum.
1. Enzymes (Recall)
Explain why starch digestion requires two separate enzymes.
Amylase breaks starch to maltose. Maltase breaks maltose to glucose. Each enzyme is specific to one substrate.
2. Bile (Recall)
Explain why bile must neutralise stomach acid before intestinal enzymes can work.
Intestinal enzymes have alkaline optimum pH. Acid would denature them by changing active site shape.
3. Emulsification (Recall)
Explain how emulsification increases digestion rate. Use SA:V.
Breaks large fat droplets into smaller ones, increasing SA:V. More surface for lipase to bind, so more fat digested per second.
4. Lead-in: Absorption
The ileum must maximise surface area and minimise diffusion distance. Suggest why.
More SA = more nutrients absorbed at once. Short distance = faster crossing. Both maximise absorption rate.
Starter
Starter: What Do You Already Know?
Instructions: Vote honestly on each statement – no guessing! Then tackle the Predict task. We're finding out what you already think, so we can test your ideas in today's lesson.
🦷
Mouth
→
🫃
Stomach
→
🫄
Small Intestine
→
❓
???
→
💪
Body Cells
Today's lesson answers the ❓ – how does digested food get from gut into blood?
✋ Part A: Agree or Disagree?
🥪 1. Food goes from your stomach straight into your blood.
DISAGREE. Food goes from stomach → small intestine first. It needs to be digested into tiny pieces before it can enter the blood.
🧠 2. Your body uses food for energy and to build new cells.
AGREE. Cells use glucose for respiration (energy) and amino acids to build new tissue. That's why food must reach the blood.
🫄 3. Most food gets absorbed in the small intestine.
AGREE. Exactly right – the ileum (part of the small intestine) is where absorption mainly happens.
📏 4. The inside of the small intestine is completely smooth, like a plastic pipe.
DISAGREE. It's covered in millions of finger-like folds (called villi) to give a huge surface area – you'll see them today!
🔮 Part B: Predict
On your mini-whiteboard: draw an arrow showing where you think food goes next after the small intestine. Use one word to label it.
Arrow from small intestine → into the BLOOD (blood vessels). Blood then carries it to all the cells in your body.
✋ Part A: Agree or Disagree?
🔬 1. Digested food molecules are small enough to pass through the gut wall.
AGREE. That's the whole point of digestion – to break food into molecules small enough to be absorbed (e.g. glucose, amino acids).
🚿 2. Diffusion moves molecules from LOW concentration to HIGH concentration.
DISAGREE. Diffusion goes the OTHER way: HIGH → LOW. Think of a drop of food colouring spreading in water.
📏 3. The small intestine has a huge surface area for absorption.
AGREE. About the size of a tennis court if you unfolded all the villi – we'll see why today!
⚡ 4. All nutrient absorption happens without needing any energy.
DISAGREE. Some nutrients need active transport, which uses ATP energy. Today's lesson covers both.
🔮 Part B: Predict
In one sentence: suggest two things that might help digested food molecules move from the gut into the blood.
Examples: diffusion from high → low concentration; a large surface area for more molecules to cross; thin walls for a short path; energy (active transport) to pump molecules against the gradient. Accept any sensible answer.
✋ Part A: Agree or Disagree?
⚡ 1. Some nutrients need energy (ATP) to be absorbed against a concentration gradient.
AGREE. That's exactly what active transport is. Glucose absorption often uses it when blood concentration is already high.
🩸 2. A rich blood supply speeds up absorption by maintaining a steep concentration gradient.
AGREE. Blood sweeps nutrients away, keeping their concentration LOW on the blood side, so diffusion keeps happening.
💪 3. A thicker gut wall would speed up diffusion of nutrients into the blood.
DISAGREE. A thinner wall speeds diffusion (shorter distance). This is why the ileum wall is only ONE cell thick.
🔄 4. Diffusion only happens when there's a concentration difference across the membrane.
AGREE. No gradient = no net movement (dynamic equilibrium). This is why we need active transport too.
🔮 Part B: Predict
Predict TWO structural features of the small intestine wall that would maximise the rate of absorption. Justify each using what you know about rate of diffusion.
Examples: (1) Large surface area (villi/folds) – more molecules can cross per second. (2) Thin wall / one cell thick – shorter diffusion path, faster rate (Fick's Law). (3) Rich blood supply – maintains steep concentration gradient. Accept any valid link to rate-of-diffusion variables.
I Do
I Do: What is Absorption? (Spec 2.32)
Key Idea: Once food is digested into small soluble molecules, it must be absorbed into the blood. This happens in the ileum. Watch the animation – molecules cross the gut wall in two different ways.
What is absorption?
Absorption = digested food molecules passing through the wall of the ileum into the bloodstream. Only small, soluble molecules fit through.
🟢 1. DIFFUSION (left side of animation)
Passive – no energy needed. Molecules move from HIGH (gut) → LOW (blood). Like rolling downhill.
⚡ 2. ACTIVE TRANSPORT (right side of animation)
Uses energy (ATP) to pump molecules AGAINST the gradient (LOW → HIGH). Like pushing uphill.
🧠 Memory: Diffusion is FREE. Active transport COSTS ATP ⚡
🎬 Absorption in the Ileum (Animated)
We Do
We Do: Absorption Process Sort
Instructions: Sort each fact into Diffusion or Active Transport.
Score: 0/6
Passive – no energy needed
Needs energy (ATP)
High to low concentration
Against the concentration gradient
Like rolling downhill
Like pushing uphill
✅ Diffusion
⚡ Active Transport
I Do
I Do: How Are Villi Adapted? (Spec 2.32)
Key Idea: The ileum wall is folded into millions of finger-like villi. Each villus has 5 key adaptations – watch the animation to see them working.
📏
1. Large surface area – millions of villi mean more nutrients absorbed at once.
🔬
2. Microvilli – tiny hair-like projections on each villus further increase SA.
📄
3. Thin wall – one cell thick = short diffusion pathway, so nutrients cross fast.
5. Lacteal – central vessel that absorbs fats (fatty acids + glycerol).
Aspire: Why do villus cells need lots of mitochondria? They perform active transport, which needs ATP. More mitochondria = more ATP.
🎬 A Villus in Action (Animated)
We Do
We Do: Label the Villus & Match Adaptations
Instructions: As a class – Part A: Select a label, then click the dashed box next to the feature it names. Part B: Match each adaptation to why it helps.
Score: 0/10
Part A: Label the Villus
Microvilli
Thin wall
Blood capillary
Lacteal
Villus
?
?
?
?
?
Part B: Match Adaptation → Reason
📏 Large SA
📄 Thin wall
🩸 Blood supply
🥛 Lacteals
⚡ Active transport
More nutrients absorbed at once
Short diffusion pathway
Maintains steep concentration gradient
Absorb fats from intestine
Moves nutrients against gradient using energy
Independent Work
Independent Work – Absorption & Villi
Instructions: Complete your Lesson 2 worksheet. Use your labelled villus diagram and knowledge organiser.
Independent Work Timer
08:00
Foundation (Grades U–1)
MCQ + short answer on villi adaptations and absorption.
Middle (Grades 2–3)
Table completion, short answer, and 4-mark exam questions.
Higher (Grades 3–5)
Extended response including a 6-mark coeliac disease question.
📋 Scaffolding
Labelled villus diagram, adaptation checklist, and key word glossary in your pack.
🏆 Success Criteria
Foundation (U–1): Name where absorption occurs, list 3 adaptations, state what lacteals do.
Middle (2–3): Explain how each adaptation helps, describe diffusion and active transport.
Higher (3–5): Link SA:V and gradients to rate, evaluate how damaged villi cause malnutrition.
Exit Ticket
Exit Ticket – Lesson 1–2 Cumulative
Instructions: 6 questions covering the Digestive System, Enzymes & Bile, and Absorption & Villi. No notes.
Digestive System
1) Name the muscular action that pushes food through the gut.
Peristalsis.
Digestive System
2) What does the large intestine absorb?
Water.
Enzymes
3) What does amylase break starch into?
Maltose.
Bile
4) Where is bile stored?
The gallbladder.
Enzymes
5) What does lipase produce?
Fatty acids and glycerol.
Villi
6) Name two adaptations of villi.
Any two: large SA, microvilli, one cell thick, blood supply, lacteals.
Digestive System
1) Name both parts of the small intestine and one function each.
Duodenum – digestion. Ileum – absorption.
Enzymes
2) Starch → _____ → _____. Name both enzymes.
Maltose (amylase), glucose (maltase).
Enzymes
3) Name the protease from the stomach.
Pepsin.
Bile
4) Explain one role of bile.
Neutralises acid for enzyme pH, OR emulsifies fats to increase SA:V.
Villi
5) Why is a good blood supply important?
Carries nutrients away, maintaining steep concentration gradient for diffusion.
Absorption
6) Name both absorption processes.
Diffusion and active transport.
Digestive System
1) Why does peristalsis work upside down?
Active muscular contractions – doesn't rely on gravity.
Enzymes
2) Why does starch need two enzymes?
Amylase: starch→maltose. Maltase: maltose→glucose. Each specific to one substrate.
Bile
3) How does emulsification increase digestion rate?
Produced: liver. Stored: gallbladder. NOT an enzyme.
Bile Job 1
Neutralises stomach acid → alkaline pH for enzymes.
Bile Job 2
Emulsifies fats → increases SA:V for lipase.
Absorption
Food → blood in ileum. Diffusion + active transport.
Villi
Finger-like projections increasing SA for absorption.
Adaptations
Large SA, microvilli, one cell thick, blood supply, lacteals.
Lacteals
Vessels inside villi that absorb fats.
Lesson 1 Arrival Task
Foundation
1) Name the five organs of the alimentary canal in order.
2) What pushes food through the gut?
3) Name the acid in the stomach.
4) What breaks large food molecules into smaller ones?
Middle
1) Name both parts of the small intestine + one function each.
2) Describe how peristalsis moves a bolus.
3) Name one accessory organ and what it produces.
4) What catalyst breaks insoluble molecules into soluble ones?
Higher
1) Explain mechanical vs chemical digestion + location where both occur.
2) Why does peristalsis work upside down?
3) Why would intestinal enzymes be destroyed in the stomach?
4) Name the catalyst. Why does specificity matter?
Lesson 1 Starter: Match the Words to the Meanings
Match each key word to its meaning. Two meanings are wrong – don’t use them!
Key Word
Possible Meanings (pick one)
1. Enzyme
A. A green-yellow liquid that helps break up fats B. A chemical in cells that is always there C. Breaking large fat droplets into many smaller ones D. A biological “scissors” that cuts big molecules into small ones E. The new molecule made after an enzyme has worked F. The molecule the enzyme works on (it gets broken down) G. The tube that carries food to the stomach
2. Substrate
3. Product
4. Bile
5. Emulsification
Write your answers like this: 1. Enzyme = D. A biological “scissors”...
Lesson 1 We Do 1: Enzyme Matching
Draw a line to match each enzyme to its substrate and product:
Enzyme
Breaks down...
Into...
Amylase
Maltase
Protease
Lipase
Lesson 1 We Do 2: Bile Fact Sort
Write each fact in the correct column:
Produced in liver | Neutralises acid | Breaks fat into droplets | Stored in gallbladder | Creates alkaline pH | Increases SA:V
What Bile Is
Job 1: Neutralise
Job 2: Emulsify
Lesson 1 Scaffolding – Foundation (Grades U–1)
Completed Enzyme Table
Group
Example
Breaks down
Into
Made where
Carbohydrases
Amylase
Starch
Maltose
Salivary glands & pancreas
Maltase
Maltose
Glucose
Small intestine
Proteases
Pepsin/Trypsin
Proteins
Amino acids
Stomach/Pancreas
Lipases
Lipase
Lipids
Fatty acids + glycerol
Pancreas
Bile Key Facts
Made in liver. Stored in gallbladder. NOT an enzyme.
Lesson 1 Independent Work – Foundation (Grades U–1)
Part A: Multiple Choice
1) Amylase breaks starch into: A) Glucose B) Amino acids C) Maltose D) Fatty acids
2) Where is bile stored? A) Liver B) Stomach C) Gallbladder D) Pancreas
3) Lipase produces: A) Amino acids B) Maltose C) Fatty acids & glycerol D) Starch
4) Which organ makes pepsin? A) Pancreas B) Liver C) Stomach D) Mouth
Part B: Short Answer
5) Name the three enzyme groups.
6) Where is bile produced?
7) State the two jobs of bile.
Part C: Long Answer
8) Describe the complete digestion of starch. Name the enzymes and products at each stage.
Part D: Exam Question [3 marks]
9) State what bile does to help digestion. Include where it is made and stored. [3]
Lesson 1 Independent Work – Middle (Grades 2–3)
Part A: Multiple Choice
1) Maltase breaks maltose into: A) Starch B) Glucose C) Amino acids D) Lipids
2) Trypsin is made in the: A) Stomach B) Mouth C) Pancreas D) Liver
3) Bile is NOT: A) An enzyme B) Made in the liver C) Stored in the gallbladder D) Alkaline
Part B: Short Answer
4) Complete: Amylase breaks _____ into _____. Maltase breaks this into _____.
5) Explain why bile is not an enzyme.
6) Define emulsification.
Part C: Long Answer
7) Explain how emulsification increases the rate of lipid digestion. Use the term SA:V.
Part D: Exam Question [4 marks]
8) Describe the role of bile in digestion. Include where it is made and stored, and explain both functions. [4]
Lesson 1 Independent Work – Higher (Grades 3–5)
Part A: Multiple Choice
1) Enzymes are specific because: A) They are big B) Each has a unique active site C) They are made of fat D) They work fast
2) Bile increases SA:V by: A) Dissolving fat B) Breaking large droplets into smaller ones C) Heating fat D) Mixing with lipase
Part B: Short Answer
3) Explain why enzymes are described as biological catalysts.
4) Explain why starch digestion requires two separate enzymes.
Part C: Long Answer
5) Explain why bile must neutralise stomach acid before intestinal enzymes can work. Include the concept of optimum pH and denaturation.
Part D: Exam Question [5 marks]
6) A patient has their gallbladder removed. Explain the effect on their digestion of fatty foods. Describe bile's normal role and why its absence causes problems. [5]
Lesson 1 Exit Ticket (Foundation U–1)
1) What does amylase break starch into?
2) Where is bile produced and stored?
3) What are bile's two jobs?
Lesson 1 Exit Ticket (Middle 2–3)
1) Starch → _____ (amylase) → _____ (maltase).
2) Name proteases from stomach and pancreas.
3) Why does emulsification help lipase?
Lesson 1 Exit Ticket (Higher 3–5)
1) Why does starch need two enzymes?
2) Why must bile neutralise acid?
3) Effect of gallbladder removal on fat digestion?
Lesson 2 Arrival Task
Foundation
1) Name the enzyme that breaks starch into maltose.
2) What two products does lipase make?
3) Where is bile produced and stored?
4) Where does digested food enter the blood?
Middle
1) Starch → _____ (amylase) → _____ (maltase).
2) Name proteases from stomach and pancreas.
3) Explain bile's two roles.
4) What is absorption and where does it occur?
Higher
1) Why does starch need two enzymes?
2) Why must bile neutralise acid?
3) How does emulsification increase rate? Use SA:V.
4) Why must ileum maximise SA and minimise diffusion distance?
Lesson 2 Starter: What Do You Already Know?
Journey: Mouth → Stomach → Small Intestine → ??? → Body Cells. Today's lesson answers the ???
Foundation (U–1)
Part A: Tick Agree, Disagree or Unsure for each statement.
Statement
Agree
Disagree
Unsure
1) Food goes from your stomach straight into your blood.
☐
☐
☐
2) Your body uses food for energy and to build new cells.
☐
☐
☐
3) Most food gets absorbed in the small intestine.
☐
☐
☐
4) The inside of the small intestine is completely smooth.
☐
☐
☐
Part B – Predict: Draw an arrow showing where food goes after the small intestine. Label it with one word.
Middle (2–3)
Part A: Tick Agree, Disagree or Unsure for each statement.
Statement
Agree
Disagree
Unsure
1) Digested food molecules are small enough to pass through the gut wall.
☐
☐
☐
2) Diffusion moves molecules from LOW to HIGH concentration.
☐
☐
☐
3) The small intestine has a huge surface area for absorption.
☐
☐
☐
4) All nutrient absorption happens without needing any energy.
☐
☐
☐
Part B – Predict: In one sentence, suggest two things that might help digested food move from gut to blood.
Higher (3–5)
Part A: Tick Agree, Disagree or Unsure. Briefly justify each choice.
Statement
A
D
?
1) Some nutrients need energy (ATP) to be absorbed against a concentration gradient.
☐
☐
☐
2) A rich blood supply speeds up absorption by maintaining a steep concentration gradient.
☐
☐
☐
3) A thicker gut wall would speed up diffusion of nutrients into the blood.
☐
☐
☐
4) Diffusion only happens when there's a concentration difference across the membrane.
☐
☐
☐
Part B – Predict: Predict TWO structural features of the small intestine wall that would maximise the rate of absorption. Justify each using rate of diffusion.
Lesson 2 We Do 1: Diffusion vs Active Transport
Write each fact in the correct column:
Passive | Needs ATP | High to low | Against gradient | Like rolling downhill | Like pushing uphill
Diffusion
Active Transport
Lesson 2 We Do: Label & Match
Part A: Label these features on the villus diagram above (if not done already).
Part B: Match each adaptation to why it helps absorption:
Adaptation
Why it helps
Large surface area
One cell thick
Good blood supply
Lacteals
Active transport
Lesson 2 Scaffolding – Foundation (Grades U–1)
Villus Adaptations
1. Large SA – millions of villi.
2. Microvilli – further increase SA.
3. One cell thick – short diffusion pathway.
4. Blood supply – steep concentration gradient.
5. Lacteals – absorb fats.
Uses: diffusion + active transport.
Sentence Starters
Absorption happens in the...
Villi increase absorption because...
The wall is one cell thick so that...
Lesson 2 Scaffolding – Middle (Grades 2–3)
Key Facts
Absorption: ileum. Diffusion + active transport.
5 adaptations: SA, microvilli, thin wall, blood supply, lacteals.
Lesson 2 Scaffolding – Higher (Grades 3–5)
Key Terms
Absorption, villus, microvilli, lacteal, diffusion, active transport, concentration gradient, SA:V
Lesson 2 Independent Work – Foundation (Grades U–1)
Part A: Multiple Choice
1) Food is absorbed in the: A) Stomach B) Duodenum C) Ileum D) Colon
2) Lacteals absorb: A) Water B) Glucose C) Fats D) Amino acids
3) Villus wall thickness: A) 5 cells B) One cell C) 10 cells D) 3 cells
4) Absorption uses diffusion and: A) Osmosis B) Active transport C) Peristalsis D) Evaporation
Part B: Short Answer
5) Name three adaptations of villi.
6) What are microvilli?
7) Why is a good blood supply important?
Part C: Long Answer
8) Describe how food is absorbed in the small intestine. Name the structures and processes involved.
Part D: Exam Question [3 marks]
9) Explain why villi increase the rate of absorption. Include how they are adapted. [3]
Lesson 2 Independent Work – Middle (Grades 2–3)
Part A: Multiple Choice
1) Blood supply helps villi because it: A) Keeps them warm B) Maintains concentration gradient C) Makes enzymes D) Produces ATP
2) Active transport needs: A) Gravity B) Energy C) Sunlight D) Oxygen
3) The ileum is part of the: A) Stomach B) Large intestine C) Small intestine D) Liver
Part B: Short Answer
4) Complete this table:
Adaptation
How it helps
Villi
One cell thick
Blood supply
Lacteals
5) Explain the difference between diffusion and active transport.
Part C: Long Answer
6) Explain why both diffusion and active transport are needed for absorption in the ileum.
Part D: Exam Question [4 marks]
7) Describe how the structure of a villus makes it adapted for absorbing digested food. [4]
Lesson 2 Independent Work – Higher (Grades 3–5)
Part A: Multiple Choice
1) Active transport is needed because: A) Diffusion is too slow B) Diffusion stops at equilibrium C) Blood flows too fast D) Villi are too small
2) A patient with flattened villi would experience: A) Better absorption B) Reduced absorption C) No change D) More villi
Part B: Short Answer
3) Explain how blood supply maintains a steep concentration gradient.
4) Why do cells in the ileum wall need lots of mitochondria?
Part C: Long Answer
5) Explain why both diffusion and active transport are essential. What would happen if only one process was available?
Part D: Exam Question [6 marks]
6) A person with coeliac disease has flattened villi. Explain how this affects nutrient absorption and could cause malnutrition. Link to specific adaptations of healthy villi. [6]
