Identify red and white cells in a blood photomicrograph
Apply diagram features to a genuine stained blood smear.
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 diagram features of red and white cells.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What kind of image is supplied?
What you will learn
- Read the preparation before identifying cells
- Do not treat a smear as intact circulation
Identify cells in a genuine smear
Whole unchanged Wright-stained photomicrograph. Use clear discs and nucleated cells; stain colour alone is insufficient and no calibrated size scale is supplied.
Enlarge image for inspection
Scroll across the enlarged image to inspect labels and cell features. The whole source image is retained. Use the identification key after trying the questions.
Check the identification key
Many pale pink discs with central pallor and no visible nucleus are red blood cells. Several larger dark-purple nucleated cells, including the upper-left cell and the central adjacent pair, are white blood cells identified by the source as lymphocytes. Use nucleus and cell shape with the supplied source identity, rather than stain colour alone. Tiny purple fragments are consistent with platelets, but this exercise asks for red and white cells. The pale spaces in a prepared smear do not directly display intact circulating plasma, and no calibrated scale is supplied for size calculation.
Read the preparation before identifying cells
The unchanged image by Echinaceapallida is a Wright-stained peripheral blood-smear photomicrograph. Many pale pink discs show central pallor and no visible nucleus: these are red blood cells. Several dark-purple nucleated cells, including an upper-left cell and a central adjacent pair, are white blood cells.
The source identifies those white cells as lymphocytes, but Core practice here requires red/white recognition. Use shape, nucleus and surrounding cytoplasm as well as the supplied preparation. Purple staining alone does not make every tiny object a white blood cell; small fragments and preparation artefacts can also appear dark.
Do not treat a smear as intact circulation
A smear spreads and stains blood on a slide. Its pale spaces do not directly reveal a measured volume of circulating plasma. Cells may overlap or be cut off at the image edge. Select clear whole examples for identification rather than forcing an answer from every partial object.
Open the full-size image and compare several cells before revealing the identification key. No calibrated scale is supplied, so screen pixels cannot establish actual diameters or a clinical blood count. This task practises recognition from a genuine image, not collecting a learner’s blood or diagnosing the source specimen.
Sources for this lesson
Pause and explain
Which feature distinguishes a clear white cell here?
Worked example
Compare a pale pink disc with the dark-purple nucleated cell at upper left. Identify both with evidence.
Show the worked solution
- The disc has central pallor and no visible nucleus.
- The upper-left cell has a prominent nucleus.
Answer Pink disc: red blood cell. Upper-left nucleated cell: white blood cell. Shape and nucleus support the identities.
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.
Find a clear pale disc and a clear nucleated cell in the photograph. Identify them.
Give me a hint
Use the many pink discs and upper-left nucleated cell.
Compare my reasoning
- The pale disc is a red cell with central pallor.
- The nucleated upper-left cell is a white cell.
Pale disc: red blood cell. Upper-left nucleated cell: white blood cell.
Look for these in your work
- Identify both image examples
- Use the nucleus distinction
Give two observations supporting red-cell identification in this smear.
Give me a hint
Look for central pallor and a missing nucleus.
Compare my reasoning
- Many cells are disc-like with a paler centre.
- No nucleus is visible in those mature red cells.
Disc-like outline with central pallor and no visible nucleus.
Look for these in your work
- Use two observations
- Avoid colour-only identification
Why should a small purple dot not automatically be labelled a white cell or its actual size calculated?
Give me a hint
Separate fragment identity and image calibration.
Compare my reasoning
- A small stained fragment is not a clearly nucleated white cell.
- No calibrated scale relates screen pixels to actual length.
Use a clear cell outline and nucleus for white-cell identification; neither colour alone nor uncalibrated pixels establishes identity and actual size.
Look for these in your work
- State identification evidence
- State the calibration limit
Common mistakes
- Calling every purple dot a white cell.
- Measuring actual cell diameter from uncalibrated screen pixels.
What can you explain now?
Which feature distinguishes a clear white cell here?
Compare with the explanation
A prominent nucleus within a larger cell
Use morphology with the source identity.
After trying it yourself, choose your next review. This is your self-assessment.
Your review choice appears on Today. Sign in to sync it across devices.
Make it stick
Hide the key and find three clear examples from each cell category.
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.