Plant Diversity: Plant Adaptations to Land and Non-Vascular Life Cycles

Vocabulary practice flashcards covering land plant adaptations, phylogenetic traits, non-vascular plants, cellular divisions, and the alternation of generations life cycle.

Desiccation

The severe loss of water and drying out of tissues, representing the single biggest evolutionary challenge plants faced during their transition to land.

Cuticle

A waxy layer covering the leaves and stems of land plants that blocks water loss, but also creates a barrier to the entry of $CO_2$.

Stomata

Microscopic pores in the epidermis of plants flanked by guard cells that open and close to facilitate $CO_2$ intake while limiting water loss.

Guard cells

Specialized epidermal cells surrounding a stoma that regulate the opening and closing of the pore for gas exchange.

Apical meristems

Localized regions of cell division at the tips of shoots and roots that facilitate directed growth, allowing shoots to grow upward and roots to grow downward.

Bryophytes

Non-vascular land plants—specifically liverworts, mosses, and hornworts—that lack vascular tissue and rely on the release of motile sperm into water for fertilization.

Vascular tissue

Internal conductive tissue functioning like a circulatory system that transports water, nutrients, and sugars throughout the plant body.

Diploid ($2N$)

The cellular condition of having two versions of each chromosome, with one version inherited from each of two parents.

Haploid ($N$)

The cellular condition of possessing only one version of each chromosome, characteristic of plant spores and gametes.

Mitosis

A type of cellular division that produces identical copies of cells, allowing a diploid cell to yield two diploid cells or a haploid cell to yield two haploid cells.

Meiosis

A specialized reductional cell division that reduces the chromosome number by half, converting one diploid ($2N$) cell into four haploid ($N$) cells.

Syngamy (Fertilization)

The fusion of two haploid ($N$) gamete cells (egg and sperm) to produce a single diploid ($2N$) zygote.

Sporophyte

The multicellular diploid ($2N$) adult plant generation that produces haploid ($N$) spores through meiosis.

Gametophyte

The multicellular haploid ($N$) adult plant generation that produces haploid ($N$) gametes through mitosis.

Sporangium

A multicellular organ on the sporophyte where diploid cells undergo meiosis to produce and protect developing haploid spores until their release.

Sporopollenin

A tough, durable, and resistant chemical polymer coating the outer walls of plant spores to protect them from harsh environmental conditions.

Gametangia

Multicellular reproductive structures on gametophytes in which gametes are produced by mitosis and protected.

Antheridium

The male gametangium of a plant that produces and protects motile sperm cells.

Archegonium

The female gametangium of a plant that produces, encloses, and protects the egg, and serves as the site for fertilization and early embryo development.

Embryophytes

A designation for land plants based on the shared derived characteristic of retaining and nourishing a multicellular diploid embryo inside maternal archegonial tissue.

Placental transfer cell

Specialized maternal cells located at the base of the embryo that develop extensive wall ingrowths to facilitate nutrient transfer to the dependent plant embryo.

Alternation of generations

A life cycle characteristic of all land plants involving regular alternation between a multicellular diploid sporophyte generation and a multicellular haploid gametophyte generation.