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IGCSE · Cambridge (CIE) · 0654

Explain vitamin C sources and connective-tissue support

Relate a vitamin source to a function without calling it fuel.

Diet · Cambridge IGCSE 0654 · B7.1

Mapped to the named 0654 section using teaching from the corresponding single-science course. A 0654-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade.

Before you begin

  • Recall large and small nutrient molecules, cell membranes and enzyme specificity.
  • Use the stated diagram keys and evidence; models are not to scale.

Work on paper. Try each question before revealing help, and explain why your method works.

Quick readiness check

Which is a useful vitamin C source?

What you will learn

  • Relate a vitamin source to a function without calling it fuel.
  • Limit a deficiency inference to the evidence supplied.

Compare vitamin C and vitamin D

Source and function are different parts of an explanation
ComponentExamples of sourcesRole
Vitamin CCitrus fruit, peppersConnective tissue; deficiency: scurvy
Vitamin DOily fish; labelled fortified foodsCalcium use; deficiency: rickets
Vitamin C supports connective tissue; vitamin D supports calcium use and bone mineralisation. Sunlight supports skin synthesis of vitamin D but is not a dietary food source. Foods supply mixtures. These examples do not prescribe an individual diet.

Use suitable food sources

Citrus fruit, peppers and many fresh fruits and vegetables supply vitamin C. The source and preparation affect the amount present. Vitamins are needed in small amounts for body functions; they do not replace carbohydrate or fat as energy-yielding fuel.

Vitamin C supports collagen formation and healthy connective tissues, including the tissues involved in wound healing. A food can supply both vitamin C and other nutrients.

Connect deficiency with a cause

A prolonged lack of adequate vitamin C can cause scurvy. Poor connective-tissue maintenance can contribute to symptoms such as bleeding gums and poor wound healing. The syllabus requires the deficiency cause, not a diagnosis from one isolated symptom.

In a supplied historical case with a documented diet missing vitamin C, link the deficiency to the function. Do not infer that every case of sore or bleeding gums is scurvy or recommend supplement doses.

Sources for this lesson

Pause and explain

Which missing component causes scurvy?

Put the idea to work

Worked example

A documented diet contains no adequate vitamin C source over a prolonged period. Name the associated deficiency disease and the relevant tissue function.

Show the worked solution
  1. Name vitamin C deficiency.
  2. Name scurvy.
  3. Connect it to collagen/connective tissue.

Answer Prolonged vitamin C deficiency can cause scurvy by impairing normal connective-tissue support.

Try a topic test

Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.

Test this topic →

From guided practice to a new situation

Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.

1 · Guided

State two vitamin C sources and one function.

Give me a hint

Choose fruit and vegetables.

Compare my reasoning
  1. Name citrus fruit and peppers.
  2. Connect to connective tissue/wound healing.

Citrus fruit and peppers; vitamin C supports healthy connective tissue and wound healing.

Look for these in your work

  • Two sources.
  • Specific function.
2 · Independent

Why is “vitamin C releases the same fuel energy as starch” misleading?

Give me a hint

A vitamin supports functions without being the main fuel.

Compare my reasoning
  1. Starch supplies glucose after digestion.
  2. Vitamin C has a connective-tissue role.

Vitamin C supports body functions; it is not the main energy-yielding carbohydrate fuel.

Look for these in your work

  • Separate nutrient roles.
  • No fuel equivalence.
3 · Transfer

An image shows bleeding gums with no dietary history. Can it alone prove scurvy? Explain.

Give me a hint

Several causes can produce a symptom.

Compare my reasoning
  1. Dietary adequacy is unknown.
  2. The symptom is not unique.
  3. More appropriate evidence is needed.

No; the image alone does not establish vitamin C deficiency or a diagnosis.

Look for these in your work

  • State the evidence limit.
  • Retain the correct deficiency association.

Common mistakes

  • Vitamin C is not the main energy fuel.
  • One symptom is not a unique diagnosis.
Recall without your notes

What can you explain now?

Which missing component causes scurvy?

Compare with the explanation

Vitamin C.

This is the named deficiency cause.

After trying it yourself, choose your next review. This is your self-assessment.

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Make it stick

Connect vitamin C, connective tissue and scurvy in one causal account.

If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.

Keep learning Sciences — Co-ordinated (Double)

Course scope and assessment

This 2028–2029 pathway maps all 152 detailed subject-content sections in the published 0654 syllabus to original teaching and staged practice. It adapts teaching from the related single-science pathways and excludes clear 0610-only topics such as classification systems, human excretion, tropic responses, food supply, population dynamics, detailed pollution and biotechnology. Some explanations may include wider single-science context. A 0654-specific objective-by-objective review, Core/Supplement audit, human subject-teacher review, supervised laboratory experience and cumulative assessment remain in progress. Written practice is self-checked and does not predict an official grade. The 2025–2027 syllabus has not been reconciled here; choose the 2028–2029 syllabus only.

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