Explain the large permanent vacuole in a plant cell
Connect cell sap and pressure with support without confusing the vacuole with cytoplasm.
Section B2.1 · Cell structure
Exam scope and assessment notes
Mapped to the named 0973 section using teaching from the corresponding single-science course. A 0973-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. This qualification reports two grades on the 9–1 scale; confirm the entry route for your zone and exam series.
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
Which description fits the large permanent vacuole?
What you will learn
- Identify a large permanent vacuole.
- Describe its contents and support role.
The central compartment
A typical mature plant cell has a large permanent vacuole containing cell sap, a watery solution of dissolved substances. The vacuole has a surrounding membrane and is distinct from the cytoplasm, which occupies the layer around it. A large clear region in a schematic can represent the vacuole when the key confirms it.
Water entering the vacuole can increase pressure against the surrounding cell contents and wall. The supporting wall resists expansion. This contributes to plant-cell firmness; the wall and vacuole have connected but different roles.
Interpret carefully
A vacuole is not a nucleus, a chloroplast or an empty air space. Its contents include water and dissolved substances. A faint region in a light micrograph does not automatically show the vacuole membrane; visibility depends on preparation and imaging.
Typical animal cells do not have the large central permanent vacuole of this plant model, although small vesicles or vacuoles may occur. Use typical-cell wording and do not treat the diagram as a universal rule for specialised cells.
Sources for this lesson
Pause and explain
What helps resist expansion when a plant cell becomes firm?
Worked example
A plant diagram labels a large fluid-filled centre A and a thin surrounding reaction-containing layer B. Identify them.
Show the worked solution
- A contains cell sap, so it is the vacuole.
- B contains cytoplasm around the central compartment.
Answer A large permanent vacuole; B cytoplasm.
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.
Identify the plant-cell compartment containing cell sap.
Give me a hint
Look for the large central compartment.
Compare my reasoning
- Cell sap is in the permanent vacuole.
- Distinguish it from the surrounding cytoplasm.
Large permanent vacuole.
Look for these in your work
- Name vacuole.
- Do not name nucleus.
Explain how the vacuole and cell wall can both contribute to firmness.
Give me a hint
One holds fluid; the other resists expansion.
Compare my reasoning
- Vacuole water contributes to internal pressure.
- The wall provides resistant support.
Fluid pressure from the contents acts against a supporting wall.
Look for these in your work
- Give both roles.
- Do not call them the same structure.
A photograph shows a pale central region but no clear internal membrane. What can and cannot be labelled with confidence?
Give me a hint
Use visible boundaries and the specimen information.
Compare my reasoning
- The plant context and pale central region may support a vacuole interpretation.
- Do not claim its surrounding membrane is resolved when it is not.
A tentative vacuole region using context; no confident label of an unseen membrane.
Look for these in your work
- Distinguish inference from visibility.
- State the limitation.
Common mistakes
- Cell sap is not air.
- The vacuole and cytoplasm are distinct.
What can you explain now?
What fills the large plant vacuole?
Compare with the explanation
Cell sap: water with dissolved substances.
The vacuole is a fluid-containing compartment.
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Make it stick
Explain the difference between cell sap, vacuole and cytoplasm.
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.