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Difficulty: MediumEvolutionary Trends and Adaptive Features in Organisms

Which of the following evolutionary trends in structural adaptation enabled pteridophytes to achieve larger body sizes and greater terrestrial independence than bryophytes?

  1. The development of lignified vascular tissues within a dominant sporophyte generationAnswer
  2. B
    The evolution of naked seeds borne on specialized cones for reproduction
  3. C
    The presence of true vascular conducting tissues within the gametophyte phase
  4. D
    The transition of reproductive structures into acellular nucleoprotein complexes

Answer

The development of lignified vascular tissues within a dominant sporophyte generation.
The development of lignified vascular tissues (xylem and phloem) in the dominant sporophyte generation is the key evolutionary innovation that allowed pteridophytes to transport water and nutrients efficiently over greater distances and maintain erect growth on land compared to non-vascular bryophytes.

Step-by-Step Solution

1
Identify the structural limitations of bryophytes in terrestrial environments.
Bryophytes lack true vascular tissue (xylem and phloem) and rely on diffusion, limiting their height and restricting them to damp habitats.
Understanding the baseline evolutionary state helps pinpoint the innovations that occurred in subsequent plant groups.
2
Analyze the major evolutionary advancement introduced by pteridophytes.
Pteridophytes developed lignified xylem and phloem in their sporophyte phase, enabling internal transport of water and structural support.
Vascularization allowed plants to grow taller and inhabit drier terrestrial niches.
3
Evaluate the change in generational dominance.
The sporophyte generation became the dominant, independent phase of the life cycle, while the gametophyte became reduced.
A dominant sporophyte with vascular tissue represents the key evolutionary trend from bryophytes to pteridophytes.

Key Concept

Evolutionary transition from non-vascular, gametophyte-dominant plants (bryophytes) to vascular, sporophyte-dominant plants (pteridophytes).
Estimated Time:1m 0s
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Topics

Evolutionary Trends and Adaptive Features in Organisms

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