CAIE A-Level Biology AS 7.1 Structure of Transport Tissues Questions

Use root, stem and leaf sections to map dicot transport tissues, then relate xylem vessel and phloem cell structures to their transport roles.

Exam points

Draw or interpret plan diagrams of herbaceous-dicot stems, roots and leaves from sections or photomicrographs.
Locate xylem and phloem in root, stem and leaf transverse sections.
Label xylem vessel elements, sieve tube elements and companion cells in transport-tissue images.
Explain how lignified xylem walls, pits and companion-cell mitochondria support water or assimilate transport.

Covered syllabus points

7.1.1—Plan diagrams of transverse sections 7.1.2—Xylem and phloem distribution 7.1.3—Xylem and phloem cell drawings 7.1.4—Structure and function

[Maximum number: 1]

dicotyledonous leaf has a palisade mesophyll layer that is approximately twice as thick as the spongy mesophyll layer.

Which plan diagram is correct?

upper surface of leaf

Figure for Question 1 — CAIE A-Level Biology AS

upper surface
of leaf

[Maximum number: 1]

The plan diagram of a transverse section through a dicotyledonous plant stem was drawn by a student. They had stained the section with a chemical that stains lignin.