Wood is composed primarily of __________.

• A. primary xylem
• B. primary phloem
• C. secondary phloem
• D. plant fibers
• E. secondary xylem

Answer: (E)

Verified step by step guidance

1. Understand the structure of a plant stem: A plant stem is composed of various tissues, including xylem and phloem, which are responsible for the transport of water, nutrients, and food throughout the plant.
2. Differentiate between primary and secondary growth: Primary growth occurs at the tips of roots and shoots, leading to an increase in length, while secondary growth occurs in the stems and roots, leading to an increase in thickness.
3. Identify the role of secondary xylem: Secondary xylem is produced by the vascular cambium during secondary growth. It is responsible for the thickening of the stem and is the main component of wood.
4. Recognize the composition of wood: Wood is primarily composed of secondary xylem, which provides structural support and facilitates the transport of water and minerals from the roots to the rest of the plant.
5. Conclude that secondary xylem is the correct answer: Based on the understanding of plant anatomy and growth, secondary xylem is the tissue that primarily makes up wood, distinguishing it from other plant tissues such as primary xylem, primary phloem, secondary phloem, and plant fibers.