USA Biology Olympiad (USABO) Practice Exam

Which characteristic is NOT shared by vascular plants?

1. Presence of xylem and phloem

2. Development of seeds

3. Ability to produce flowers

4. Complex root systems

The correct answer is: Development of seeds

Vascular plants are characterized by the presence of specialized tissues, including xylem and phloem, which allow for efficient transport of water, nutrients, and sugars throughout the plant. These tissues form a critical aspect of the plant's structure and function, enabling them to grow larger and live in a variety of habitats. While some vascular plants develop seeds, particularly angiosperms (flowering plants) and gymnosperms (such as conifers), not all vascular plants produce seeds. For example, ferns and horsetails are vascular plants that reproduce via spores rather than seeds. This distinction highlights that the development of seeds is not a universally shared characteristic among all vascular plants. The ability to produce flowers is also specific to certain groups of vascular plants, namely angiosperms, and complex root systems are prevalent among vascular plants, but there are exceptions in the plant kingdom. Therefore, the development of seeds is indeed the characteristic that is not ubiquitous among all vascular plants, making it the correct answer to the question.