Locate transport tissues in a dicot stem diagram
Read the ring of bundles and distinguish the inner xylem from outer phloem.
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 root model and tissue functions.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which region is at the centre of this dicot stem model?
What you will learn
- Locate the vascular-bundle ring
- Identify xylem and phloem using pith and cortex
The stem has a different layout
In a typical non-woody dicot stem cross-section, vascular bundles form a ring around central pith. Each bundle contains xylem towards the pith and phloem towards the outside cortex. The outer epidermis surrounds the stem.
A single bundle can be drawn enlarged beside the whole section. Keep the scale change clear: the enlarged bundle is not a second stem. Establish inside and outside before labelling.
Position survives rotation
Inside means towards the stem centre; outside means towards its surface. Turning the page changes left and right on the screen but does not reverse which tissue is closer to the pith.
Use the specimen context. A root’s central xylem star is not the usual bundle ring of this stem model. A bundle may also contain support tissues; an outer supporting fibre cap is not the same as the phloem conducting layer beneath it.
Sources for this lesson
Pause and explain
Which side of a stem bundle contains xylem in this model?
Worked example
In a stem bundle, A faces the pith and B faces the cortex. Identify A and B.
Show the worked solution
- A is the inner water-conducting xylem region.
- B is the outer phloem region.
Answer A: xylem. B: phloem. The bundles form a ring around pith.
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.
Place xylem and phloem in a bundle drawn between pith and cortex.
Give me a hint
Use the organ centre as your reference.
Compare my reasoning
- Put xylem nearer pith.
- Put phloem nearer cortex.
Pith → xylem → phloem → outer cortex, for the stated typical bundle.
Look for these in your work
- Give the correct relative order
- Keep cortex separate
A bundle is on the left side of a stem diagram. Which tissue is on its right, towards the centre?
Give me a hint
Page right is inward only in this stated location.
Compare my reasoning
- The centre is rightward from the left-side bundle.
- The inward bundle tissue is xylem.
Xylem is on the centre-facing right side of this bundle. Its identity depends on inward position, not page right in every bundle.
Look for these in your work
- Identify xylem
- Qualify the page direction
Two sections show a central xylem star and a ring of bundles around pith. Match them to root and stem.
Give me a hint
Compare organ arrangements, not colour.
Compare my reasoning
- The central star matches the typical young dicot root.
- The bundle ring around pith matches the typical non-woody dicot stem.
Central star: root. Bundle ring around pith: stem.
Look for these in your work
- Assign both organs
- Use their tissue layouts
Common mistakes
- Using top/bottom without establishing the organ centre.
- Labelling a whole bundle as only xylem.
What can you explain now?
Which side of a stem bundle contains xylem in this model?
Compare with the explanation
The side nearer the pith
Xylem is internal relative to phloem.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Draw one stem bundle and label the side facing the pith.
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.