Separate the functions of the cell wall membrane cytoplasm and nucleus
Explain support, controlled exchange, reaction sites and genetic control.
Section B2.1 · Cell structure
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 the distinction between plant, animal and bacterial cells. Read the supplied evidence before drawing a conclusion.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Where is the plant cell wall relative to the cell membrane?
What you will learn
- Distinguish the cell wall from the membrane.
- Connect four structures with their functions.
Two boundaries do different jobs
A plant cell wall provides support and helps the cell retain its shape. It is outside the cell membrane. The wall is not the selectively controlling boundary: the cell membrane controls the movement of substances into and out of the cell. Plant cells have both boundaries.
Cytoplasm is where many chemical reactions occur. It is not an empty space and it is not a synonym for the nucleus. Structures such as mitochondria occur within the cytoplasm; a label pointing to the surrounding material should identify cytoplasm.
Keep genetic control distinct
The nucleus contains genetic material that helps control cell activities. A nucleus is not the site of photosynthesis and does not itself form a rigid external wall. Link the structure to a specific function rather than saying it is important.
A bacterial cell has a membrane, cytoplasm and a wall, but no membrane-bound nucleus. Its genetic material occurs in the cytoplasm. The genetic control role can exist without a nucleus; the organisation of the DNA differs.
Sources for this lesson
Pause and explain
Which function best matches cytoplasm?
Worked example
A plant diagram labels outer rigid boundary A, inner thin boundary B, interior material C and genetic compartment D. Identify each and its function.
Show the worked solution
- A is the supporting cell wall; B is the controlling membrane.
- C is cytoplasm, a site of reactions.
- D is the nucleus containing genetic material.
Answer A wall: support; B membrane: exchange control; C cytoplasm: reactions; D nucleus: genetic control.
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.
A cell keeps its shape using a rigid outer layer. Name the layer and function.
Give me a hint
Do not confuse exchange with support.
Compare my reasoning
- Identify the outer cell wall.
- Link rigidity to support.
Cell wall; supports the cell and helps retain shape.
Look for these in your work
- Name wall.
- Explain support.
Compare the functions of membrane and nucleus in a typical animal cell.
Give me a hint
One is a boundary, the other contains genetic material.
Compare my reasoning
- Membrane controls entry and exit.
- Nucleus contains genetic information controlling activities.
Membrane: exchange control; nucleus: genetic control.
Look for these in your work
- Keep functions separate.
- Use specific roles.
A plant cell wall remains intact but its membrane is damaged. Does the wall guarantee normal controlled exchange? Explain.
Give me a hint
The two boundaries are not interchangeable.
Compare my reasoning
- Controlled exchange depends on the membrane.
- A remaining wall can still support the cell.
- Support does not replace membrane control.
No; wall support does not restore membrane exchange control.
Look for these in your work
- Identify the damaged function.
- Retain the wall’s separate role.
Common mistakes
- Wall and membrane are different structures.
- Cytoplasm is not an empty hole.
What can you explain now?
Which structure controls movement into and out of a cell?
Compare with the explanation
The cell membrane.
The wall provides support; the membrane controls exchange.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Explain the four roles without using the word important.
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.