Q29.3-1CC. - Campbell Biology

Question

List the key derived traits found in monilophytes and seed plants, but not in lycophytes.

Step-by-Step Solution

Answer

Seed plants and monilophytes contain megaphylls whereas, lycophytes contain microphylls in their structure. The traits such as the initiation of new root branches at various points are found in monilophytes and seed plants but not in lycophytes. 

Step 1: Moniophytes and seed plants

Moniophytes are plants that contain vascular bundles in their structures (xylem and phloem) and reproduce by spores. They do not contain seeds and flowers in their structures. Their examples are ferns and their relatives.

The plants that contain seeds in their structure are seed plants or spermatophytes. They reproduce by fertilization (fusion of male and female gamete). Their examples are gymnosperms and angiosperms. 

Lycophytes are vascular plants that reproduce by spore formation. They possess alteration of generation, in which sporophyte generation is dominant. Some of them are heterosporous (produce spores of different sizes), while some are homosporous (produce spores of the same size). 

Step 2: Microphylls and megaphylls

Both microphylls and megaphylls indicate leaf structures. The former indicates a short leaf with a single unbranched vein, and the latter indicates a leaf with many large veins with branching. Microphylls are present in lycophytes, whereas megaphylls are present in seed plants and moniophytes. 

Step 3: Characteristics found in monilophytes and seed plants but not in lycophytes

Many traits are shared by monilophytes and seed plants but not by lycophytes. Some of these traits, such as new root branches in monilophytes and seed plants initiated at various points along with the length of an existing root. This characteristic is not found in lycophytes.