Explain calcium sources and the skeleton
Connect a mineral ion to bones and teeth.
Section 7.1 · Diet
Exam scope and assessment notes
Core and Extended · Biology 0970, 2026–2028. Use the stated specimen features and evidence. Diagrams are schematic. Written practice is self-checked; human subject-teacher review, supervised practical competence and cumulative assessment remain pending. Cambridge states that IGCSE 0970 has the same subject content as IGCSE 0610, with 9–1 grading. This StudyForA pathway maps the 2026–2028 syllabus only. This 9–1 graded qualification is available only in a limited number of administrative zones. Confirm that your centre can enter you for this code and exam series with Cambridge International. Cambridge has published a separate syllabus for 2029. StudyForA has not reconciled that version yet; this page supports exams in 2026, 2027 and 2028 only.
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 nutrient category contains calcium?
What you will learn
- Connect a mineral ion to bones and teeth.
- Evaluate source claims using the stated food label.
Compare calcium and iron
| Component | Examples of sources | Role |
|---|---|---|
| Calcium | Dairy; labelled fortified sources | Bones and teeth |
| Iron | Meat, pulses, fortified cereal | Needed for haemoglobin |
Find calcium in food
Milk, yoghurt and cheese are common calcium sources. Other sources include appropriately fortified plant drinks and calcium-set tofu; the product label matters because not every plant drink or tofu preparation has the same calcium content.
Calcium contributes to the strength and mineralisation of bones and teeth. It is a mineral ion rather than a vitamin, protein or carbohydrate fuel.
Keep paired roles distinct
Calcium and vitamin D have connected but different roles: calcium supplies a mineral component, while vitamin D supports its absorption and use. Finding one in a food does not prove the other is present in adequate amounts.
When explaining a dietary comparison, identify a documented calcium source and the skeletal role. The exercise does not prescribe an intake amount or establish bone health from one food photograph.
Pause and explain
Which source claim is justified?
Worked example
A label states that a plant drink is calcium-fortified. Explain the mineral’s relevance to developing bones.
Show the worked solution
- Use the stated fortification evidence.
- Identify calcium as a mineral.
- Connect it to bone mineralisation.
Answer The drink supplies calcium that contributes to bone and tooth mineralisation.
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.
Give two calcium sources and its main skeletal function.
Give me a hint
Use dairy or documented fortified sources.
Compare my reasoning
- Name milk and yoghurt.
- State bone/teeth mineralisation.
Milk and yoghurt; calcium contributes to strong bones and teeth.
Look for these in your work
- Two sources.
- Skeletal function.
Why does a calcium label not establish the drink’s vitamin D content?
Give me a hint
Different nutrients have separate contents.
Compare my reasoning
- Calcium is a mineral.
- Vitamin D is a vitamin.
- Read the vitamin label separately.
The nutrients are distinct; calcium presence is not evidence of vitamin D content.
Look for these in your work
- Category distinction.
- Evidence limit.
Two plant drinks are shown; only A is documented as calcium-fortified. Which has better supplied evidence as a calcium source?
Give me a hint
Do not infer contents from packaging colour.
Compare my reasoning
- Use A’s stated fortification.
- B’s calcium content is not given.
A has the documented calcium source; B remains unknown from the supplied information.
Look for these in your work
- Use the stated evidence.
- Do not invent B’s content.
Common mistakes
- Not every plant drink is fortified.
- Calcium is not vitamin D.
What can you explain now?
Which source claim is justified?
Compare with the explanation
A drink labelled calcium-fortified can supply calcium.
Use actual label evidence.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Name a calcium source and explain why it does not replace vitamin D.
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.