CIE iGCSE Co-Ordinated Science B8.1 Xylem and phloem Exam Style Questions Paper 1
▶️ Answer/Explanation
In a dicotyledonous stem, the vascular bundles are arranged in a ring. The phloem is located towards the outside of the vascular bundle, and the xylem is towards the inside. In the diagram of the stem, label X points to the outer part of the vascular bundle — this is the phloem.
In a dicotyledonous root, the vascular tissue is arranged in a central cylinder (stele). The xylem is in the centre and the phloem is located between the arms of the xylem. In the diagram of the root, label Y points to the phloem (the outer part of the vascular cylinder between the xylem arms).
Therefore, both X and Y are phloem. This matches row A.
✅ Answer: (A)
▶️ Answer/Explanation
In the cross-section of a plant root, the central tissue S is the xylem. Xylem vessels are located in the centre of the root and are responsible for transporting water and mineral ions from the roots to the rest of the plant. Phloem transports sucrose and amino acids and is found in the outer regions. Option D correctly identifies tissue S as xylem transporting water.
✅ Answer: (D)
✅ Answer: (D)
▶️ Answer/Explanation
Xylem cells are found in the vascular bundles of the leaf, particularly in the midrib and veins. They are characterised by thick lignified cell walls and appear as small, thick-walled cells with narrow lumens. In the leaf cross-section, the xylem is typically located on the upper side of the vascular bundle. Option B correctly identifies the xylem cells.
✅ Answer: (B)
✅ Answer: (B)
▶️ Answer/Explanation
Dye dissolved in water is taken up by the cut stem in the same way as water and mineral ions normally would be.
Water and dissolved substances move upward through the stem exclusively in the xylem vessels.
The dye therefore travels up the xylem and stains the petals at the top.
✅ Answer: (D)
Water and dissolved substances move upward through the stem exclusively in the xylem vessels.
The dye therefore travels up the xylem and stains the petals at the top.
✅ Answer: (D)
▶️ Answer/Explanation
In a dicotyledonous root, the xylem tissue is arranged in a central, star-shaped core at the very centre of the root.
This central position gives the root strength to resist pulling (tension) forces as water is drawn upward.
Diagram C shows the label pointing to this central star-shaped region, which is the xylem.
✅ Answer: (C)
This central position gives the root strength to resist pulling (tension) forces as water is drawn upward.
Diagram C shows the label pointing to this central star-shaped region, which is the xylem.
✅ Answer: (C)