Identify lymphocytes and phagocytes in diagrams
Use nucleus shape and cytoplasm to distinguish two white-cell examples.
Section B9.4 · Blood
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 white-cell diagram identification.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which two diagrams are white cells?
What you will learn
- Recognise the lymphocyte example
- Recognise a phagocyte example without overgeneralising
Recognise the lymphocyte example
In the original comparison, B is a lymphocyte. Its large round nucleus occupies much of the cell, leaving a relatively narrow rim of cytoplasm. That combination supports this example’s identity; do not describe the nucleus as the whole cell or mistake the thin rim for plasma outside it.
A and C supply comparison: A is a mature red cell without a nucleus, and C is a neutrophil, a phagocyte type. The drawn colours are conventions. White-cell identification depends on the supplied morphology and specimen context, not merely being a purple circle.
Recognise a phagocyte example without overgeneralising
C shows a segmented or lobed nucleus and more visible surrounding cytoplasm. These features are characteristic of the neutrophil example used here. Phagocytes engulf pathogens by phagocytosis. Other phagocyte types can have different nucleus shapes, so avoid claiming every phagocyte must look exactly like this drawing.
The syllabus asks learners to recognise lymphocytes and phagocytes in diagrams and photomicrographs. Start with this simplified comparison, then move to the source-confirmed microscope examples. A still diagram of a phagocyte is not itself evidence that engulfing is occurring at that instant; identification and active-function evidence are separate.
Sources for this lesson
Pause and explain
Which identification matches B and C?
Worked example
Name B and C and justify each using its nucleus.
Show the worked solution
- B has a large round nucleus with a narrow cytoplasm rim.
- C is the neutrophil example with a lobed nucleus.
Answer B lymphocyte; C phagocyte (neutrophil example). Their nucleus shapes support the distinction.
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 B and give two supporting features.
Give me a hint
Look at the round nucleus and remaining cytoplasm.
Compare my reasoning
- The nucleus is large and round.
- A relatively narrow cytoplasm rim remains.
B lymphocyte: large round nucleus and narrow cytoplasm rim.
Look for these in your work
- Name lymphocyte
- Use both structural features
Identify C and state the example’s nucleus feature.
Give me a hint
The drawing is a neutrophil example.
Compare my reasoning
- Its nucleus is segmented or lobed.
- Neutrophils are phagocytes.
C phagocyte, represented by a neutrophil with a lobed nucleus.
Look for these in your work
- Name phagocyte
- Qualify the neutrophil example
A different phagocyte has a kidney-shaped nucleus. Must it be rejected because C is lobed?
Give me a hint
One example is not the entire group.
Compare my reasoning
- Phagocyte types can differ in nuclear shape.
- Use source identity and full morphology for the new specimen.
No; the neutrophil drawing does not define every phagocyte shape. Use the new specimen’s verified identity and features.
Look for these in your work
- Avoid an absolute shape rule
- Use specimen evidence
Common mistakes
- Calling the lymphocyte nucleus the entire cell.
- Claiming all phagocyte types have identical lobed nuclei.
What can you explain now?
Which identification matches B and C?
Compare with the explanation
B lymphocyte; C phagocyte example
B has a large round nucleus; C a lobed one.
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Make it stick
Identify B and C without colour and qualify the phagocyte example.
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.