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Plant Diversity and Life Cycles in General Biology

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Termini in questo insieme (26)

  • Origin of land plants
    Land plants originated from green algae about 470 million years ago (mya).
  • Major plant groups
    Bryophytes (mosses, liverworts, hornworts), seedless vascular plants (ferns), and seed plants (gymnosperms and angiosperms).
  • Alternation of generations in plants
    Plants alternate between multicellular haploid gametophyte and diploid sporophyte stages.
  • Dominant stage in bryophytes
    The gametophyte stage is dominant in bryophytes (non-vascular plants).
  • Dominant stage in seedless vascular plants
    The sporophyte stage is dominant in seedless vascular plants like ferns.
  • Two types of vascular tissue
    Xylem transports water and minerals; phloem transports sugars and organic nutrients.
  • Functions of roots and leaves
    Roots anchor plants and absorb water and nutrients; leaves increase surface area for photosynthesis.
  • Sporophylls
    Leaves that bear sporangia, the structures producing spores.
  • Homosporous spore production
    Most seedless vascular plants produce one type of spore that develops into a bisexual gametophyte.
  • Heterosporous spore production
    All seed plants and some seedless vascular plants produce two types of spores: megaspores (female) and microspores (male).
  • Phylum Lycophyta
    Includes club mosses, spike mosses, and quillworts; small herbaceous plants with vascular tissue.
  • Phylum Monilophyta
    Includes ferns, horsetails, and whisk ferns; most widespread seedless vascular plants.
  • Significance of seedless vascular plants
    They formed major forests in the Devonian and Carboniferous, contributing to coal deposits and global cooling.
  • Seed plant origin and importance
    Seed plants originated about 360 mya and became dominant terrestrial producers due to seed adaptations.
  • Components of a seed
    A seed contains an embryo, a food supply, and a protective seed coat.
  • Four key seed plant traits
    Reduced gametophytes, heterospory, ovules, and pollen.
  • Reduced gametophytes in seed plants
    Gametophytes are microscopic and dependent on the sporophyte for nutrition.
  • Ovule structure
    An ovule consists of a megaspore within a megasporangium, surrounded by protective integuments.
  • Pollen and its function
    Microspores develop into pollen grains, which are male gametophytes enclosed in a pollen wall, enabling dispersal.
  • Pollination process
    Transfer of pollen to the ovule-containing part of a seed plant, leading to fertilization by sperm from the pollen tube.
  • Evolutionary advantages of seeds
    Seeds can remain viable longer, disperse farther, and contain stored energy to support early growth.
  • Gymnosperms
    Seed plants with 'naked seeds' exposed on cones; includes conifers, cycads, ginkgo, and gnetophytes.
  • Angiosperm key adaptations
    Flowers and fruits; flowers facilitate pollination, fruits protect seeds and aid dispersal.
  • Flower structure
    Composed of sepals, petals (attract pollinators), stamens (produce pollen), and carpels (produce ovules).
  • Human dependence on seed plants
    Seed plants provide food, construction materials, fuel, and medicine.
  • Threats to plant diversity
    Habitat destruction causes extinction of many plant species and associated animal species.