Connect protein sources with growth and repair
Link dietary protein to amino acids used by cells.
Section B7.1 · Diet
Cross-referenced to the 2028–2029 0653 section using original teaching from the related single-science courses. A 0653-specific objective-by-objective and Core/Supplement review is in progress. Written practice is self-checked and 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
What builds proteins?
What you will learn
- Link dietary protein to amino acids used by cells.
- Classify cellular protein synthesis as assimilation.
Sources supply building blocks
| Component | Examples of sources | Role |
|---|---|---|
| Protein | Eggs, beans, lentils | Amino acids for growth and repair |
Find protein in different diets
Meat, fish, eggs and dairy foods provide protein; beans, lentils and other pulses are important plant sources. A menu need not include meat to contain protein. Food labels refer to mixtures rather than pure single nutrients.
Proteins are large molecules made from amino acids. Digestive proteases contribute to breaking dietary proteins down, making amino acids available for absorption and cell use.
Explain the function precisely
Cells use amino acids to make their own proteins for growth and tissue repair. Enzymes and many other functional cell components are proteins. Eating an enzyme does not mean that exact intact protein is transferred into every cell.
Dietary protein supplies building blocks; assimilation is their uptake and use by cells. Distinguish this from digestion in the gut and absorption across the gut lining.
Sources for this lesson
Pause and explain
Which example is assimilation?
Worked example
A supplied menu replaces a meat portion with beans. What nutrient category can beans still provide, and what is its tissue role?
Show the worked solution
- Identify beans as a protein source.
- Name amino acids after digestion.
- Connect them to new body proteins.
Answer Beans can supply protein building blocks for growth and repair.
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.
Name one animal and one plant protein source and the main tissue function.
Give me a hint
Use eggs and lentils.
Compare my reasoning
- Identify both sources.
- State growth/repair.
Eggs and lentils; protein supports growth and tissue repair.
Look for these in your work
- Both source types.
- Correct function.
Why does eating protein not mean intact dietary proteins simply become all the body’s enzymes?
Give me a hint
Digestion changes the molecules first.
Compare my reasoning
- Protein is digested.
- Amino acids are absorbed.
- Cells make required proteins.
Cells use absorbed amino acids to synthesise their own proteins, including enzymes.
Look for these in your work
- Include digestion and cell synthesis.
- No intact-transfer claim.
A student identifies new muscle protein production as absorption. Correct the process and location.
Give me a hint
It occurs inside cells.
Compare my reasoning
- Absorption is movement across the gut lining.
- New protein production uses amino acids in cells.
It is assimilation in cells, following absorption from the intestine.
Look for these in your work
- Correct process.
- Correct location.
Common mistakes
- Plant foods can provide protein.
- Cells make their own proteins from amino acids.
What can you explain now?
Which example is assimilation?
Compare with the explanation
A cell uses absorbed amino acids to make protein.
This is cellular uptake/use.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Trace a protein source through digestion, absorption and cell use.
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.