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Difficulty: MediumEvolutionary Trends and Adaptive Features in Organisms

In the evolutionary progression of land plants, pteridophytes represent a major structural advancement over bryophytes. Which of the following features constitutes the primary evolutionary innovation that enabled pteridophytes to achieve larger body sizes and adapt more effectively to terrestrial life?

  1. Development of true vascular tissues comprising xylem and phloem for internal transportAnswer
  2. B
    Reliance on unicellular rhizoids for anchoring and direct absorption of water
  3. C
    Production of seeds enclosed within protective floral ovaries
  4. D
    Possession of an acellular thallus lacking differentiation into true organs

Answer

The development of true vascular tissues comprising xylem and phloem for internal transport represents the key evolutionary advancement of pteridophytes over bryophytes.
The development of specialized vascular tissues (xylem and phloem) is the hallmark evolutionary trend distinguishing pteridophytes from bryophytes. Xylem provides structural support via lignified cells and conducts water from roots, while phloem distributes photosynthetic products, allowing pteridophytes to reach much larger sizes than bryophytes.

Step-by-Step Solution

1
Analyze the evolutionary relationship between bryophytes and pteridophytes.
Bryophytes (mosses, liverworts) lack specialized vascular tissues (xylem and phloem) and rely on simple diffusion, limiting their height and habitat range.
Understanding the structural limitations of primitive land plants helps identify key evolutionary milestones.
2
Identify the defining structural innovation of pteridophytes (ferns and fern allies).
Pteridophytes evolved true vascular bundles (xylem with lignified cells for water transport/support and phloem for food conduction).
Vascularization allowed plants to transport materials efficiently over greater heights and distances.
3
Evaluate the choices to select the feature unique to pteridophytes relative to bryophytes while excluding gymnosperm/angiosperm traits.
True vascular tissues represent the accurate evolutionary transition step.
Seed formation and fruit enclosures evolved later in spermatophytes.

Key Concept

Evolutionary transition from non-vascular to vascular land plants
Estimated Time:1m 0s
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Topics

Evolutionary Trends and Adaptive Features in Organisms

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