BSCBO-103: Pteridology and Telome Theory

The Telome theory, proposed by Walter Zimmermann, suggests that vascular plants evolved from simple, leafless ancestral forms called telomes. It explains how these telomes, through a series of evolutionary modifications, gave rise to the complex vascular systems found in modern plants.

<p>A telome is the single-nerved, extreme portion of a plant body, extending from the tip to the next branching point. A mesome is the older segment below the telome, formed by dichotomous growth.</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>Interconnection of cells, differentiation of meristem, rotation of cell axis, shifting of chief phases in alternation of generation, differentiation of various permanent tissues</p> Signup and view all the answers

<p>Zosterophyllum, Rhynia, Horneophyton, and Psilophyton</p> Signup and view all the answers

<p>telomes</p> Signup and view all the answers

<p>It fully explains the whorled or spiral arrangement of sporangia in ancient plants</p> Signup and view all the answers

<p>Thomas argued that the Telome Theory does not adequately explain the whorled or spiral arrangement of sporangia observed in some ancient plants.</p> Signup and view all the answers

<p>A central vascular cylinder in a plant stem or root</p> Signup and view all the answers

<p>Protostele and Siphonostele</p> Signup and view all the answers

<p>A protostele is the simplest and most primitive type of stele, characterized by a solid central vascular cylinder, with a core of xylem surrounded by a layer of phloem and finally enclosed by a pericycle. It lacks a central pith.</p> Signup and view all the answers

<p>Haplostele</p> Signup and view all the answers

<p>The various types of protostele are haplostele, actinostele, plectostele, mixed protostele, and protostele with mixed pith. Each of these variations reflects a unique arrangement of vascular tissue within the central cylinder.</p> Signup and view all the answers

<p>A type of stele with a central pith surrounded by xylem</p> Signup and view all the answers

<p>Cladosiphonic siphonosteles lack leaf gaps and are found in plants without leaves, while phyllosiphonic siphonosteles have leaf gaps and are found in plants with leaves. This distinction is based on the presence or absence of gaps in the vascular cylinder for leaf traces.</p> Signup and view all the answers

<p>Both A and B, as both hypotheses are supported by evidence</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>Eustele</p> Signup and view all the answers

<p>An atactostele is characterized by scattered vascular strands throughout the ground tissue. This arrangement lacks a clear order or organization, unlike other stele types.</p> Signup and view all the answers

<p>A polycyclic stele has more than one concentric cylinder of vascular tissue, which can be either solenosteles or dictyosteles. Such a structural arrangement provides a highly organized and efficient system for transport and support.</p> Signup and view all the answers

<p>A stele with more than one vascular cylinder</p> Signup and view all the answers

<p>The evolution of the stelar system likely started with the protostele, a simple, solid vascular cylinder. This evolved into the siphonostele, with a central pith surrounded by vascular tissue, allowing for greater structural support and more efficient transport. Further modifications led to solenostele, dictyostele, eustele, and atactostele, reflecting increasing complexity and adaptation for diverse growth forms.</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>Syntelome</p> Signup and view all the answers

<p>A polycyclostele is a type of stele characterized by the development of multiple, separate steles within a plant. This structural arrangement provides a highly complex and efficient vascular system for transporting resources throughout the plant.</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>The origin of pith in the siphonostele is a debated topic. Two main hypotheses exist: the intrastelar origin, which suggests that tracheary elements of the xylem transform into parenchyma to form the pith, and the extrastelar origin, which proposes that cortical cells migrate into the stelar axis to form the pith.</p> Signup and view all the answers

<p>Atactostele</p> Signup and view all the answers

<p>The evolutionary sequence of stele types is generally considered to progress from the simplest protostele to more complex forms like the siphonostele, solenostele, dictyostele, and eustele. This evolutionary trajectory reflects increasing specialization and adaptation for efficient resource transport and structural support in various plant groups.</p> Signup and view all the answers