Which of the following is not an evolutionary trend among...

Which of the following is not an evolutionary trend among plants?
a. developing vascular tissues
b. becoming seedless
c. having a dominant diploid generation
d. producing nonmotile gametes
e. producing two types of spores

Key Concepts

Seed Evolution

The evolution of seeds is a critical development in plant history. It involves the protection and nourishment of the embryo, enabling plants to survive harsh conditions and disperse over wider areas. Unlike becoming seedless, the trend has been towards the development and enhancement of seeds as a means of reproductive success.

Heterospory (Production of Two Types of Spores)

Heterospory is the production of two distinct types of spores—microspores and megaspores—that develop into male and female gametophytes, respectively. This evolutionary trend leads to improved specialization in reproductive functions and is a precursor to the development of seeds.

Dominant Diploid Generation (Sporophyte Dominance)

In the course of evolution, many plants have shifted from a life cycle dominated by the haploid (gametophyte) form to one where the diploid (sporophyte) generation is dominant. This trend, seen particularly in seed plants, provides advantages such as increased genetic redundancy and the capacity to mask deleterious mutations.

Nonmotile Gamete Production

The evolution of nonmotile gametes in plants minimizes the dependence on water for fertilization, as gametes are no longer required to swim. This adaptation is crucial for successful reproduction in a terrestrial environment, leading to greater reproductive efficiency and diversity.

Vascular Tissue Development

Vascular tissues, including xylem and phloem, represent a major evolutionary innovation in plants. They allow for efficient water, nutrient, and photosynthate transport throughout the plant, enabling increased size, structural complexity, and colonization of diverse terrestrial environments.

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