Chapter 25: Seedless Plants

These flashcards cover the important concepts related to seedless plants and their adaptations, structure, and ecological roles as discussed in Chapter 25.

What is the connection between the ancestors of plants and algae?

Plants share a common ancestor with charophytes (green algae) in the archaeplastida supergroup.

List some shared characteristics between green algae and plants.

Multicellularity, cell walls with cellulose, chloroplasts with chlorophyll a & b, and starch as a storage molecule.

What are the major divisions of seedless plants?

Seedless nonvascular plants and seedless vascular plants.

What adaptations were necessary for green algae to transition to land?

Protection from desiccation, structural support, and new strategies for gamete transfer.

What is the dominant form of Bryophytes?

Haploid gametophyte is the dominant form.

In plant reproduction, what protects the developing sperm and eggs?

Multicellular gametangia protect sperm and eggs.

How do plants prevent desiccation?

Plants evolve a waxy cuticle and controllable stomata for gas exchange.

What are apical meristems?

Continuously dividing cells that allow roots and shoots to grow toward resources.

What role do mycorrhizae play in plant adaptation?

Mycorrhizae assist in water and mineral absorption through mutualism with fungi.

What is the alternation of generations in plants?

The life cycle involves alternation between multicellular haploid (gametophyte) and diploid (sporophyte) forms.

Describe the structure of sporophytes in seedless vascular plants.

Sporophytes are branched and independent of the gametophyte for nutrition.

What type of vascular tissue is found in seedless vascular plants?

Xylem and phloem for transporting water, minerals, and nutrients.

What are the characteristics of microphylls?

Microphylls are small, spine-shaped leaves supported by a single strand of vascular tissue.

What are megaphylls?

Megaphylls are leaves with a highly branched vascular system, providing greater photosynthetic productivity.

What are sporophylls?

Leaves modified to bear sporangia, which produce spores.

Difference between homosporous and heterosporous spore production?

Homosporous produces a single type of spore; heterosporous produces two types of spores, male and female.

What is the ecological importance of mosses?

Mosses are pioneer species in nutrient-poor soils and major primary producers in cold regions.

Identify the three phyla of bryophytes.

Marchantiophyta (liverworts), Anthocerotophyta (hornworts), and Bryophyta (mosses).

How do liverworts differ in structure from typical mosses?

Liverworts often have elevated gametophytes resembling miniature trees, while mosses are typically low-growing.

What is the significance of hornworts in their ecosystem?

Hornworts are good colonizers of moist soils and have symbiotic relationships with nitrogen-fixing cyanobacteria.

What is the role of sporopollenin in plant reproduction?

Sporopollenin protects walled haploid spores during airborne dispersal.

What distinguishes the life cycle of charophytes from that of land plants?

Charophytes have only a multicellular haploid stage; zygotes undergo meiosis without alternation of generations.

What adaptations do plants have to cope with higher light intensity on land?

Plants have evolved a waxy cuticle and controlled stomata for gas exchange while minimizing water loss.

How do ferns reproduce?

Ferns undergo a life cycle with a dominant sporophyte and produce haploid spores via meiosis.

What are the old fossil records of seedless vascular plants?

The oldest seedless vascular plant fossils date back to approximately 425 million years ago.

Describe the significance of secondary metabolites in plants.

They deter, repel, or poison competitors, herbivores, and parasites.

What conditions favored the expansion of multicellular green algae onto land?

Higher levels of CO2, light intensity, and fewer herbivores led to adaptations for land life.

In what way do mosses contribute to soil formation?

Mosses promote the weathering of rocks and can accelerate topsoil formation.

What is the role of the gametophyte in bryophytes?

The gametophyte produces eggs and sperm and relies on the sporophyte for nutrients.

What is unique about the sporophyte of the hornworts?

Hornworts have a long, tapered sporophyte that resembles a horn.

Explain the importance of peat moss (Sphagnum).

Peat moss is an important wetland species, used as a renewable fuel resource and soil conditioner.

What are the adaptations required for plant reproduction on land?

Protection from desiccation, air dispersal of spores, and gametophyte protection.

How do ferns maintain ecological balance?

Ferns serve as primary producers and can grow in understory or epiphytic environments.