Why is "Saying protein is mainly for energy" a common mistake in Balanced Diet?

Why it happens: Students lump all the 'big' nutrients together as 'food = energy'. How to avoid it: Protein is for **growth and repair** of tissues. The energy nutrients are **carbohydrate** (main source) and **lipid** (energy store). Source: Edexcel Biology examiner reports

Why is "Claiming fibre is digested for energy" a common mistake in Balanced Diet?

Why it happens: Students assume everything you eat must be broken down and used. How to avoid it: Fibre is **not digested**. Its job is to **add bulk** so the gut can move food along and **prevent constipation**. Source: Edexcel Biology examiner reports 2022–2024

Why is "Writing that iron is just 'for the blood' or 'for red blood cells'" a common mistake in Balanced Diet?

Why it happens: Students remember a blood link but not the precise role. How to avoid it: Be specific: iron is needed to make **haemoglobin**, the molecule that **carries oxygen**. A lack causes **anaemia**. Source: Edexcel Biology examiner reports

Why is "Saying vitamin D makes bones directly / forgetting it absorbs calcium" a common mistake in Balanced Diet?

Why it happens: Vitamin D and calcium are both linked to bones, so students merge them. How to avoid it: State the chain: **vitamin D helps absorb calcium**, and the **calcium** then builds **bones and teeth**. Source: Edexcel Biology examiner reports

Why is "Stating who needs more energy without giving a reason" a common mistake in Balanced Diet?

Why it happens: Students answer the 'who' but not the 'why' the question demands. How to avoid it: Always justify using **activity, age or pregnancy**, e.g. 'more active → respires more → needs more energy'. Source: Edexcel Biology examiner reports

Structure and Functions in Living OrganismsEdexcel IGCSE Science(Double Award)-Biology (4WSD0-1B)

Balanced Diet

Q: Why is "Listing only the macronutrients and vitamins/minerals when naming diet components" a common mistake in Balanced Diet?

Why it happens: Water and fibre feel less like 'nutrients', so they are left out. How to avoid it: Memorise all **seven** components — carbohydrate, protein, lipid, vitamins, minerals, **water** and **dietary fibre**. The last two are easy marks. Source: Edexcel Biology examiner reports

Work through the notes, try the practice questions, then take the quiz. The report tells you exactly what to revise next.

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Balanced Diet — Edexcel International GCSE Science (Double Award) Biology (4WSD0-1B) Study Notes

What a balanced diet is, the seven components (carbohydrate, protein, lipid, vitamins, minerals, water and fibre) with their sources and functions, the key vitamins and minerals (A, C, D, calcium, iron), and how energy needs change with activity, age and pregnancy. Covers Double Award Biology spec 2.24–2.26, assessed on Biology Paper 1 (4WSD0/1B).

What you’ll learn

Mapped to the Edexcel IGCSE 4SD0 syllabus (2026 onwards).

2.24 — Know that a balanced diet should include appropriate proportions of carbohydrate, protein, lipid, vitamins, minerals, water and dietary fibre.
2.25 — Identify the sources and describe the functions of carbohydrate, protein, lipid (fats and oils), vitamins A, C and D, the mineral ions calcium and iron, water and dietary fibre.
2.26 — Understand that energy requirements vary with activity levels, age and pregnancy.

What a balanced diet means (spec 2.24)

The right proportions of all seven components, plus enough energy.

A balanced diet is one that contains all the nutrients your body needs, in the correct proportions, together with enough energy for your activity level.

It must include seven components:

Carbohydrate
Protein
Lipid (fats and oils)
Vitamins
Minerals (mineral ions)
Water
Dietary fibre

A useful memory hook is "Croissants Provide Loads of Vital Minerals + Water + Fibre" (Carbohydrate, Protein, Lipid, Vitamins, Minerals, Water, Fibre).

Why "proportions" matters. You need a lot of carbohydrate but only tiny amounts of vitamins and minerals. A diet is only "balanced" if each component is present in the right relative amount — too little or too much causes problems (this is malnutrition).

Exam tip. If a question asks you to define a balanced diet, you must say "all the nutrients in the correct proportions" AND "with the right amount of energy" — leaving out "proportions" or "energy" loses marks.

Balanced diet = all nutrients in correct proportions + enough energy.
Seven components: carbohydrate, protein, lipid, vitamins, minerals, water, fibre.
Malnutrition = too little OR too much of a component.

See the full worked example for balanced diet →

The energy and building nutrients: carbohydrate, protein, lipid (spec 2.25)

Carbohydrate for energy, protein for growth/repair, lipid for energy store and insulation.

These three are needed in large amounts.

Carbohydrate

Source: bread, rice, pasta, potatoes, sugary foods.
Function: the main source of energy for respiration.

Protein

Source: meat, fish, eggs, beans, pulses, dairy.
Function: growth and repair of tissues (building new cells, muscle, enzymes).

Lipid (fats and oils)

Source: butter, oils, cheese, fatty/oily fish, nuts.
Function: an energy store, and provides insulation to reduce heat loss (it also helps protect organs).

Learn one source and one function for each macronutrient — these are guaranteed marks.

Exam tip. Don't muddle the energy nutrients: carbohydrate is the MAIN energy source, while lipid is an energy STORE (and also insulates). Protein is not an energy nutrient — it is for growth and repair.

Carbohydrate = main energy source (bread, rice, pasta).
Protein = growth and repair (meat, fish, eggs, beans).
Lipid = energy store + insulation (butter, oils, nuts).

See the full worked example for balanced diet →

Vitamins and minerals: A, C, D, calcium, iron (spec 2.25)

Tiny amounts, but each prevents a specific deficiency problem.

Vitamins and minerals are needed in very small amounts, but a shortage causes a specific deficiency disease.

Vitamins

Vitamin	Source	Function	Deficiency
A	liver, carrots, dairy	needed for vision (seeing in dim light) and a healthy immune system	poor night vision
C	citrus fruits, fresh vegetables	keeps tissues healthy; prevents scurvy	scurvy (bleeding gums)
D	oily fish, eggs, sunlight on skin	helps the body absorb calcium for strong bones	weak/soft bones (rickets)

Minerals (mineral ions)

Mineral	Source	Function	Deficiency
Calcium	milk, cheese, dairy	makes strong bones and teeth	weak bones and teeth
Iron	red meat, liver, leafy greens	needed to make haemoglobin in red blood cells (to carry oxygen)	anaemia (tiredness)

Link to remember. Vitamin D and calcium work as a pair — you need vitamin D to absorb the calcium, and the calcium then builds bones and teeth. A shortage of either gives weak bones.

Exam tip. Be precise with iron: it is used to make haemoglobin (the molecule that carries oxygen) — don't just write "for blood".

Vitamin A = vision + immune system; Vitamin C = prevents scurvy.
Vitamin D = calcium absorption; calcium = bones and teeth.
Iron = makes haemoglobin to carry oxygen (lack = anaemia).

See the full worked example for balanced diet →

Water and dietary fibre (spec 2.25)

Water for reactions and transport; fibre keeps the gut moving.

These two are easy to forget, but examiners love them because students leave them out.

Water

Source: drinks and most foods (fruit, vegetables).
Function: about two-thirds of the body is water. It is needed:
- as the solvent for chemical reactions in cells,
- to transport substances (e.g. in the blood/plasma),
- to help remove waste and control temperature.

Dietary fibre (roughage)

Source: wholegrain cereals, vegetables, fruit skins, pulses.
Function: it is not digested, but it adds bulk to food so the muscles of the gut can grip and push it along.
This keeps food moving (peristalsis through the gut) and prevents constipation.

Exam tip. For fibre, the marking points are "adds bulk/roughage", "keeps food/gut moving" and "prevents constipation". Do not say fibre is "digested for energy" — fibre is not digested.

Water = solvent for reactions + transport; ~two-thirds of the body.
Fibre = adds bulk, keeps food moving, prevents constipation.
Fibre is NOT digested — never say it gives energy.

See the full worked example for balanced diet →

Why energy needs vary: activity, age and pregnancy (spec 2.26)

More active, growing or pregnant people need more energy.

The amount of energy a person needs from food is not fixed — it changes with three main factors.

1. Activity level

A more active person (e.g. a manual worker or athlete) uses more energy in respiration, so needs more energy from food.
Someone with a sedentary (inactive) lifestyle needs less.

2. Age

A growing teenager needs a lot of energy (building new tissue and very active), often more than a less active adult.
Energy needs generally fall in old age as activity and growth slow down.

3. Pregnancy

A pregnant woman needs extra energy (and extra nutrients such as protein, calcium and iron) to grow the developing fetus and support her own body.

Activity, age and pregnancy all raise the energy a person needs from their diet.

Exam tip. When a question gives two people and asks "who needs more energy?", always justify your answer by referring to activity, age or pregnancy (e.g. "the builder needs more because he is more active, so respires more").

More active person → needs more energy from food.
Growing teenagers need a lot of energy; needs fall in old age.
Pregnant women need extra energy (and extra nutrients) for the fetus.

See the full worked example for balanced diet →

How it’s examined

Assessed on Biology Paper 1 (4WSD0/1B), 2 hours, 110 marks, untiered (Double Award has no Biology Paper 2). Common question shapes: 'name a component of a balanced diet and state its function' (1–2 marks), match-the-source/function tables (3–4 marks), a named deficiency (e.g. 'which vitamin prevents scurvy?'), and a 'who needs more energy and why?' comparison using activity/age/pregnancy. Precise function wording (e.g. 'iron is needed to make haemoglobin', 'vitamin D helps absorb calcium') reliably scores the marks.

Sources: Pearson Edexcel International GCSE Science (Double Award) 4SD0 specification — Issue 4, September 2024 (valid for 2026 onwards); Pearson Edexcel International GCSE Biology 4BI1 specification — Issue 4 (shared Biology Paper 1 content); Pearson Edexcel 4SD0 / 4BI1 examiner reports 2022–2024. Last reviewed 2026-06-04.

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Step-by-step worked examples — Balanced Diet

Step-by-step solutions to past-paper-style questions on balanced diet, written exactly the way a tutor would explain them at the board.

1Name the components of a balanced diet (Getting started)
Getting started• 4WSD0/1B style — short answer• balanced-diet, spec-2.24
Question
A balanced diet contains carbohydrate, protein, lipid, minerals, water and one other component. Name the missing component and one more from the list, and state the function of carbohydrate. (3 marks)
Step-by-step solution
1. Step 1
  Missing components (1). The seven components are carbohydrate, protein, lipid, vitamins, minerals, water and dietary fibre. The one missing from the list given is vitamins (fibre is also acceptable as the 'one more').
2. Step 2
  Name one more (1). Dietary fibre (or vitamins, whichever you did not give above).
3. Step 3
  Function of carbohydrate (1). Carbohydrate is the main source of energy for the body (used in respiration).
Answer
Missing components are vitamins and dietary fibre. Carbohydrate is the main source of energy.
Examiner tip
Learn all seven components as a set. Students most often forget vitamins, water and fibre — the three 'invisible' ones.
2Match the macronutrient to its function (Getting started)
Getting started• 4WSD0/1B style — short answer• macronutrients, protein, lipid, spec-2.25
Question
State the main function of (a) protein and (b) lipid in the diet, and give one food source of each. (4 marks)
Step-by-step solution
1. Step 1
  Protein function (1). Needed for growth and repair of tissues (building new cells).
2. Step 2
  Protein source (1). Meat, fish, eggs or beans/pulses.
3. Step 3
  Lipid function (1). An energy store and provides insulation (reduces heat loss).
4. Step 4
  Lipid source (1). Butter, oils, cheese or nuts.
Answer
Protein: growth and repair; source — meat/fish/eggs/beans. Lipid: energy store + insulation; source — butter/oils/cheese/nuts.
Examiner tip
Protein is for growth and repair, NOT energy. Keep lipid (energy store + insulation) separate from carbohydrate (main energy source).
3Identify a vitamin from its deficiency (Building confidence)
Building confidence• 4WSD0/1B style — structured• vitamins, scurvy, spec-2.25
Question
A person eats almost no fresh fruit or vegetables and develops scurvy (bleeding gums). (a) Which vitamin are they short of? (b) Name a food that would provide it. (c) State one other function of a different vitamin in the diet. (3 marks)
Step-by-step solution
1. Step 1
  (a) Vitamin (1). Scurvy is caused by a lack of vitamin C.
2. Step 2
  (b) Source (1). Citrus fruits (e.g. oranges) or fresh vegetables provide vitamin C.
3. Step 3
  (c) Other vitamin function (1). Vitamin A is needed for vision (and a healthy immune system); OR vitamin D helps the body absorb calcium for strong bones.
Answer
(a) Vitamin C; (b) citrus fruit/fresh vegetables; (c) vitamin A for vision/immunity OR vitamin D for calcium absorption.
Examiner tip
Link each vitamin to its specific role: C → scurvy, A → vision/immunity, D → calcium absorption. Vague 'keeps you healthy' answers score nothing.
4Explain why fibre and water are needed (Building confidence)
Building confidence• 4WSD0/1B style — structured• fibre, water, spec-2.25
Question
Dietary fibre and water are both parts of a balanced diet even though fibre is not digested. Explain the function of each. (4 marks)
Step-by-step solution
1. Step 1
  Fibre — bulk (1). Fibre is not digested but adds bulk/roughage to the food in the gut.
2. Step 2
  Fibre — gut movement (1). This lets the gut muscles grip and push the food along, keeping it moving and preventing constipation.
3. Step 3
  Water — reactions (1). Water acts as the solvent in which chemical reactions in cells take place.
4. Step 4
  Water — transport (1). Water is needed to transport dissolved substances around the body (e.g. in the blood).
Answer
Fibre adds bulk so the gut can push food along, preventing constipation. Water is the solvent for reactions and transports substances around the body.
Examiner tip
Never write that fibre is 'digested for energy' — it is not digested. The fibre marks are 'bulk', 'keeps food moving' and 'prevents constipation'.
5Compare the energy needs of two people (Stretch)
Stretch• 4WSD0/1B style — extended• energy, activity, pregnancy, spec-2.26
Question
Compare the daily energy needs of (a) a manual labourer and an office worker of the same age, and (b) a pregnant woman and a non-pregnant woman. Justify each comparison. (4 marks)
Step-by-step solution
1. Step 1
  (a) Activity (1). The labourer needs more energy because they are more active, so they respire more to release the energy for muscle activity.
2. Step 2
  (a) Office worker (1). The office worker is less active, so respires less and needs less energy from food.
3. Step 3
  (b) Pregnancy (1). The pregnant woman needs more energy to grow the developing fetus and support her own body.
4. Step 4
  (b) Justification (1). She also needs extra nutrients (e.g. protein for growth, iron and calcium), not just extra energy.
Answer
The labourer needs more energy than the office worker because he is more active (respires more). The pregnant woman needs more energy than the non-pregnant woman to grow the fetus, plus extra protein, iron and calcium.
Examiner tip
Always justify a 'who needs more?' answer with activity, age or pregnancy. A comparison with no reason scores zero.
6Build a sources-and-functions table (Stretch)
Stretch• 4WSD0/1B style — extended• minerals, iron, calcium, spec-2.25
Question
For EACH of calcium, iron and vitamin D, give one food source and its function, then explain the link between vitamin D and calcium. (7 marks)
Step-by-step solution
1. Step 1
  Calcium (2). Source: milk/cheese/dairy. Function: makes strong bones and teeth.
2. Step 2
  Iron (2). Source: red meat/liver/leafy greens. Function: needed to make haemoglobin in red blood cells (to carry oxygen).
3. Step 3
  Vitamin D (2). Source: oily fish/eggs (or made in skin in sunlight). Function: helps the body absorb calcium.
4. Step 4
  The link (1). Without enough vitamin D the body cannot absorb the calcium, so even with calcium in the diet the bones become weak.
Answer
Calcium (dairy) → bones and teeth; iron (red meat/greens) → makes haemoglobin to carry oxygen; vitamin D (oily fish/sunlight) → helps absorb calcium. Vitamin D is needed to absorb calcium, so a lack of either gives weak bones.
Examiner tip
The vitamin D–calcium link is a favourite higher-mark point. State the cause-and-effect: vitamin D → absorbs calcium → strong bones.

Model Answers — Balanced Diet

High-scoring sample answers for balanced diet on the Pearson Edexcel IGCSE Biology Paper 1 (4WSD0/1B) paper, with examiner-style notes mapping each response to the mark scheme and assessment objectives.

Question 1
4WSD0/1B style2 marks
What is meant by a 'balanced diet'? (2 marks)
Model answer
A balanced diet is one that contains all the nutrients the body needs in the correct proportions (1), together with the right amount of energy for the person's needs (1).

The seven components are carbohydrate, protein, lipid, vitamins, minerals, water and dietary fibre.
Why this scores
1 mark for 'correct proportions of all nutrients', 1 mark for 'right amount of energy'. Both ideas are needed for full marks.
Question 2
4WSD0/1B style4 marks
State the function of carbohydrate and the function of protein in the diet, giving one food source of each. (4 marks)
Model answer
Carbohydrate — the main source of energy for the body (used in respiration) (1). Source: bread, rice, pasta or potatoes (1).

Protein — needed for growth and repair of tissues (1). Source: meat, fish, eggs or beans (1).
Why this scores
1 mark per function + 1 per source. Carbohydrate = energy; protein = growth and repair (not energy).
Question 3
4WSD0/1B style6 marks
Describe the functions of vitamin A, vitamin C, calcium and iron in a healthy diet, and name one source of each. (6 marks)
Model answer
Vitamin A — needed for vision (seeing in dim light) and a healthy immune system. Source: liver, carrots or dairy.

Vitamin C — keeps tissues healthy and prevents scurvy (bleeding gums). Source: citrus fruits / fresh vegetables.

Calcium — needed to make strong bones and teeth. Source: milk, cheese or dairy.

Iron — needed to make haemoglobin in red blood cells, which carries oxygen. Source: red meat, liver or leafy green vegetables.
Why this scores
Up to 6 marks — function + source credited across the four nutrients. Keyword credits: 'scurvy', 'haemoglobin', 'bones and teeth'.
Question 4
4WSD0/1B style5 marks
Explain why both water and dietary fibre must be included in a balanced diet. (5 marks)
Model answer
Water (about two-thirds of the body):

It is the solvent in which chemical reactions take place inside cells (1).

It transports dissolved substances around the body, e.g. in the blood plasma (1).

It also helps remove waste and control body temperature (1).

Dietary fibre (roughage):

It is not digested, but it adds bulk to the food so the gut muscles can grip and push it along (1).

This keeps food moving through the gut and prevents constipation (1).
Why this scores
Reward two clear roles for water (solvent + transport) and the fibre points 'bulk' and 'prevents constipation'. Do not credit 'fibre gives energy'.
Question 5
4WSD0/1B style — extended open response7 marks
Explain why the daily energy requirement of a person is not the same for everyone, referring to activity level, age and pregnancy. (7 marks)
Model answer
Energy is released from food in respiration, so the more a person uses, the more they must take in to stay in balance.

Activity level

A more active person (e.g. a manual labourer or athlete) uses more energy for muscle activity, so they respire more and need more energy from food.

An inactive person needs less, and any excess energy is stored as fat (which can lead to obesity).

Age

A growing child or teenager needs a lot of energy because they are building new tissue and are usually very active.

Energy needs generally decrease in old age as growth stops and people become less active.

Pregnancy

A pregnant woman needs extra energy to grow the developing fetus and support the changes in her own body.

She also needs extra nutrients such as protein, iron and calcium.

So energy needs depend on how much energy the body uses, which varies with activity, age and whether a woman is pregnant.
Why this scores
Up to 7 marks for clear, justified points across all three factors. The strongest answers always link 'more active → respires more → needs more energy'.
Question 6
4WSD0/1B style — extended open response8 marks
A teenager rarely goes outside, eats little oily fish and avoids dairy. They complain of tiredness and are found to have weak bones. Use your knowledge of a balanced diet to explain the likely causes and suggest dietary changes. (8 marks)
Model answer
Weak bones

Strong bones need calcium, but the teenager avoids dairy, so their calcium intake is low (1).

The body needs vitamin D to absorb calcium (1), but they get little oily fish and rarely go outside (sunlight on skin makes vitamin D), so their vitamin D is also low (1).

With low vitamin D, even the small amount of calcium they do eat is poorly absorbed, so the bones become weak (1).

Tiredness

Tiredness can be caused by a lack of iron (1), which is needed to make haemoglobin in red blood cells to carry oxygen; too little iron leads to anaemia (1).

Dietary changes

Eat more dairy (milk, cheese) for calcium and more oily fish/eggs for vitamin D, and spend more time outdoors in sunlight (1).

Eat more iron-rich foods such as red meat or leafy green vegetables (1).
Why this scores
Rewards joined-up reasoning: low calcium AND low vitamin D (so calcium not absorbed) → weak bones; low iron → less haemoglobin → tiredness/anaemia. Mark scheme credits the cause AND a sensible dietary fix.

Key Definitions and Keywords — Balanced Diet

Definitions to memorise and the exact keywords mark schemes credit for balanced diet answers — sharpened from recent examiner reports for the 2026 Pearson Edexcel IGCSE Biology Paper 1 (4WSD0/1B) sitting.

Balanced diet
Examiner keyword
A diet that contains all the nutrients the body needs (carbohydrate, protein, lipid, vitamins, minerals, water and fibre) in the correct proportions, plus the right amount of energy.
Carbohydrate
Examiner keyword
A nutrient (e.g. in bread, rice, pasta) that is the body's main source of energy, released in respiration.
Protein
Examiner keyword
A nutrient (e.g. in meat, fish, eggs, beans) needed for the growth and repair of body tissues.
Lipid (fats and oils)
Examiner keyword
A nutrient (e.g. in butter, oils, nuts) used as an energy store and for insulation to reduce heat loss.
Scurvy
Examiner keyword
A deficiency disease (e.g. bleeding gums) caused by a lack of vitamin C in the diet.
Iron
Examiner keyword
A mineral ion needed to make haemoglobin in red blood cells, which carries oxygen. A lack of iron causes anaemia.
Calcium
Examiner keyword
A mineral ion needed to make strong bones and teeth; its absorption requires vitamin D.
Dietary fibre (roughage)
Examiner keyword
The indigestible part of plant food that adds bulk so the gut can push food along, keeping it moving and preventing constipation.

Common Mistakes and Misconceptions — Balanced Diet

The traps other students keep falling into on balanced diet questions — taken from recent Pearson Edexcel IGCSE Biology Paper 1 (4WSD0/1B) examiner reports and mark schemes — and how to avoid them.

✕Saying protein is mainly for energy
Edexcel Biology examiner reports
Why it happens
Students lump all the 'big' nutrients together as 'food = energy'.
How to avoid it
Protein is for growth and repair of tissues. The energy nutrients are carbohydrate (main source) and lipid (energy store).
✕Claiming fibre is digested for energy
Edexcel Biology examiner reports 2022–2024
Why it happens
Students assume everything you eat must be broken down and used.
How to avoid it
Fibre is not digested. Its job is to add bulk so the gut can move food along and prevent constipation.
✕Writing that iron is just 'for the blood' or 'for red blood cells'
Edexcel Biology examiner reports
Why it happens
Students remember a blood link but not the precise role.
How to avoid it
Be specific: iron is needed to make haemoglobin, the molecule that carries oxygen. A lack causes anaemia.
✕Saying vitamin D makes bones directly / forgetting it absorbs calcium
Edexcel Biology examiner reports
Why it happens
Vitamin D and calcium are both linked to bones, so students merge them.
How to avoid it
State the chain: vitamin D helps absorb calcium, and the calcium then builds bones and teeth.
✕Listing only the macronutrients and vitamins/minerals when naming diet components
Edexcel Biology examiner reports
Why it happens
Water and fibre feel less like 'nutrients', so they are left out.
How to avoid it
Memorise all seven components — carbohydrate, protein, lipid, vitamins, minerals, water and dietary fibre. The last two are easy marks.
✕Stating who needs more energy without giving a reason
Edexcel Biology examiner reports
Why it happens
Students answer the 'who' but not the 'why' the question demands.
How to avoid it
Always justify using activity, age or pregnancy, e.g. 'more active → respires more → needs more energy'.

Past paper style quiz

Get a report showing which sub-topics you've nailed and which ones still need work.

Balanced Diet — Edexcel International GCSE Science (Double Award) Biology (4WSD0-1B) Study Notes

Vitamin

Source

Function

Deficiency

liver, carrots, dairy

needed for vision (seeing in dim light) and a healthy immune system

poor night vision

citrus fruits, fresh vegetables

keeps tissues healthy; prevents scurvy

scurvy (bleeding gums)

oily fish, eggs, sunlight on skin

helps the body absorb calcium for strong bones

weak/soft bones (rickets)

Mineral

Source

Function

Deficiency

Calcium

milk, cheese, dairy

makes strong bones and teeth

weak bones and teeth

Iron

red meat, liver, leafy greens

needed to make haemoglobin in red blood cells (to carry oxygen)

anaemia (tiredness)

The amount of energy a person needs from food is not fixed — it changes with three main factors.

1. Activity level

A more active person (e.g. a manual worker or athlete) uses more energy in respiration, so needs more energy from food.
Someone with a sedentary (inactive) lifestyle needs less.

2. Age

A growing teenager needs a lot of energy (building new tissue and very active), often more than a less active adult.
Energy needs generally fall in old age as activity and growth slow down.

3. Pregnancy

A pregnant woman needs extra energy (and extra nutrients such as protein, calcium and iron) to grow the developing fetus and support her own body.

Activity, age and pregnancy all raise the energy a person needs from their diet.

Balanced Diet

Detailed Notes

What you’ll learn

How it’s examined

1Name the components of a balanced diet (Getting started)

2Match the macronutrient to its function (Getting started)

3Identify a vitamin from its deficiency (Building confidence)

4Explain why fibre and water are needed (Building confidence)

5Compare the energy needs of two people (Stretch)

6Build a sources-and-functions table (Stretch)

Balanced diet

Carbohydrate

Protein

Lipid (fats and oils)

Scurvy

Iron

Calcium

Dietary fibre (roughage)

✕Saying protein is mainly for energy

✕Claiming fibre is digested for energy

✕Writing that iron is just 'for the blood' or 'for red blood cells'

✕Saying vitamin D makes bones directly / forgetting it absorbs calcium

✕Listing only the macronutrients and vitamins/minerals when naming diet components

✕Stating who needs more energy without giving a reason

Past paper style quiz

Balanced Diet

Detailed Notes

What you’ll learn

How it’s examined

1Name the components of a balanced diet (Getting started)

2Match the macronutrient to its function (Getting started)

3Identify a vitamin from its deficiency (Building confidence)

4Explain why fibre and water are needed (Building confidence)

5Compare the energy needs of two people (Stretch)

6Build a sources-and-functions table (Stretch)

Balanced diet

Carbohydrate

Protein

Lipid (fats and oils)

Scurvy

Iron

Calcium

Dietary fibre (roughage)

✕Saying protein is mainly for energy

✕Claiming fibre is digested for energy

✕Writing that iron is just 'for the blood' or 'for red blood cells'

✕Saying vitamin D makes bones directly / forgetting it absorbs calcium

✕Listing only the macronutrients and vitamins/minerals when naming diet components

✕Stating who needs more energy without giving a reason

Past paper style quiz