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Difficulty: MediumEvolutionary Trends in Plants and Animal Systems

In the evolutionary transition of plants from aquatic and moist habitats to dry land, which structural adaptation first enabled pteridophytes to overcome the height limitations of bryophytes by facilitating long-distance transport and mechanical support?

  1. The differentiation of true vascular tissues containing lignified xylem and phloemAnswer
  2. B
    The development of non-vascular rhizoids for water absorption in bryophytes
  3. C
    The formation of naked seeds enclosed within protective floral ovaries in gymnosperms
  4. D
    The complete separation of fluids in a three-chambered internal transport organ

Answer

The differentiation of true vascular tissues containing lignified xylem and phloem
The development of specialized conducting tissues (lignified xylem for water and mechanical strength, plus phloem for organic nutrients) represents the main evolutionary milestone that enabled pteridophytes and higher vascular plants to grow tall on land.

Step-by-Step Solution

1
Analyze the evolutionary limitation of bryophytes (mosses and liverworts).
Bryophytes lack true vascular bundles and rely on simple diffusion across short distances, keeping them small and restricted to moist habitats.
Without specialized conducting cells, water transport is constrained by physical diffusion limits.
2
Identify the key evolutionary advance in pteridophytes (ferns).
Pteridophytes were the first plant group to develop true vascular tissues (xylem and phloem).
Lignified xylem vessels provide compressive strength for vertical support as well as efficient water transport over tall distances.

Key Concept

Evolution of plant vascular systems and land adaptation trends
Estimated Time:1m 0s
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Topics

Evolutionary Trends in Plants and Animal Systems

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