Plant Evolution and Diversity: Land Colonization, Vascularity, and Reproductive Cycles

What is the evidence supporting the evolution of plants from green algae?

Morphological and molecular evidence shows that charophytes are the closest relatives of land plants.

What are the two main stages in the plant life cycle?

The gametophyte (haploid) and sporophyte (diploid) stages.

What adaptations allowed plants to colonize land?

Waxy cuticle to prevent desiccation, stomata for gas exchange, and roots for water absorption.

Why are liverworts and mosses not considered monophyletic?

They do not share a single common ancestor exclusive to them, as they belong to different lineages.

What distinguishes vascular plants from nonvascular plants?

Vascular plants have specialized tissues (xylem and phloem) for transporting water and nutrients.

What are the two types of vascular plants?

Vascular seedless plants (like ferns) and vascular seed plants (gymnosperms and angiosperms).

What is the role of stomata in plants?

Stomata are specialized cells that allow for gas exchange between the outside air and the plant.

What is the function of mycorrhizae in plants?

Mycorrhizae are symbiotic associations between fungi and land plants that help plants obtain nutrients.

What is alternation of generations in plants?

A reproductive cycle where plants alternate between haploid gametophyte and diploid sporophyte stages.

What is the significance of walled spores in plants?

Walled spores produced in sporangia are resistant to harsh environments, aiding in survival and reproduction.

What are gametangia in plants?

Gametangia are organs where gametes are produced; archegonia produce eggs and antheridia produce sperm.

What is the role of apical meristems in plant growth?

Apical meristems are regions of continuous growth where cells differentiate into various tissues.

What are the two main groups of seed plants?

Gymnosperms (cone plants) and angiosperms (flowering plants).

What is the primary source of food for land animals?

Plants are the ultimate source of most food eaten by land animals.

What is the primary characteristic that defines land plants?

Land plants have terrestrial ancestors and are adapted to life on land.

What is the difference between monocots and dicots?

Monocots have one cotyledon, while dicots have two.

What is the role of xylem in vascular plants?

Xylem transports water and dissolved minerals throughout the plant.

What is the role of phloem in vascular plants?

Phloem transports sugars produced by photosynthesis throughout the plant.

What is the significance of sporopollenin in spores?

Sporopollenin makes spore walls resistant to harsh environmental conditions.

What is the primary function of the cuticle in plants?

The cuticle is a waxy layer that prevents water loss and desiccation.

How do land plants transport gametes?

Land plants use pollen for gamete transportation instead of relying on water.

What is the difference between haploid and diploid stages in plants?

Haploid (n) gametophytes produce gametes, while diploid (2n) sporophytes produce spores.

What is the role of placental transfer cells in plants?

They transfer nutrients from the parent plant to the developing embryo.

What is the significance of the term 'embryophytes'?

Embryophytes refer to land plants due to the dependency of the embryo on the parent plant.

What is the evolutionary significance of charophytes?

Charophytes are considered the closest living relatives of land plants, providing insight into plant evolution.

What challenges did plants face when moving to land?

Challenges included scarcity of water and lack of structural support.

What are the main characteristics of the plant kingdom?

Eukaryotic, multicellular, autotrophic, with cell walls made of cellulose.

What are the five key traits that appear in nearly all land plants?

Alternation of generations, multicellular dependent embryos, walled spores produced in sporangia, multicellular gametangia, and apical meristems.

When did plants first appear on land according to fossil evidence?

At least 470 million years ago.

What are the three phyla of bryophytes?

Liverworts (phylum Hepatophyta), mosses (phylum Bryophyta), and hornworts (phylum Anthocerophyta).

What is the primary life cycle stage in bryophytes?

Gametophytes are the dominant life cycle stage.

What is a seed composed of?

An embryo and nutrients surrounded by a protective coat.

What distinguishes gymnosperms from angiosperms?

Gymnosperms are 'naked seed' plants, while angiosperms are flowering plants.

What type of vascular tissue conducts water and minerals in vascular plants?

Xylem.

What is the function of phloem in vascular plants?

Phloem distributes sugars, amino acids, and other organic products.

What are microphylls and megaphylls?

Microphylls are leaves with a single vein; megaphylls have a highly branched vascular system.

What is the ecological importance of mosses?

Mosses can inhabit diverse environments, help retain nitrogen in the soil, and form peat deposits.

What is the significance of Sphagnum moss?

Sphagnum forms peat deposits and is an important global reservoir of organic carbon.

How do bryophyte sporophytes differ from their gametophytes?

Sporophytes are typically smaller and simpler, growing out of archegonia.

What evolutionary advantage does vascular tissue provide to plants?

It allows for increased height and structural support.

What is the role of roots in vascular plants?

Roots anchor the plants and enable them to absorb water and nutrients from the soil.

What is the process of fertilization in bryophytes?

Sperm swim through water to fertilize the egg within the archegonium.

What is the difference between homosporous and heterosporous plants?

Homosporous plants produce one type of spore, while heterosporous plants produce megaspores and microspores.

What are the two clades of seedless vascular plants?

Phylum Lycophyta (club mosses) and Phylum Monilophyta (ferns and relatives).

What role did seedless vascular plants play during the Carboniferous period?

They contributed to the formation of the first forests and helped remove CO2 from the atmosphere.

What is the function of stomata in plant sporophytes?

Stomata facilitate gas exchange.

What are the two types of gametophytes produced by heterosporous plants?

Megagametophytes (female) and microgametophytes (male).

What is the significance of the alternation of generations in plants?

It allows for the transition between haploid and diploid stages in the life cycle.

What is the primary function of apical meristems in plants?

Apical meristems are responsible for the growth of roots and shoots.

What is a sporangium?

A structure that produces and discharges spores.

What is the role of rhizoids in bryophytes?

Rhizoids anchor gametophytes to the substrate.

What is the primary habitat of seedless vascular plants?

They are usually restricted to moist environments.

What is the significance of flagellated sperm in bryophytes?

Flagellated sperm require water to swim to the egg for fertilization.

What is the evolutionary significance of vascular plants?

Vascular plants allowed for greater height and complexity in plant life.

What is the function of the seta in bryophyte sporophytes?

The seta is the stalk that supports the sporangium.

What is peat and how is it formed?

Peat is partially decayed organic material formed in waterlogged conditions.

What is the role of lignin in xylem cells?

Lignin strengthens water-conducting cells and provides structural support.