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Study guide 8

Relationship Between Algae and Land Plants

  • Both algae and land plants share a common ancestor

  • Both groups are photoautotrophic, multicellular eukaryotes, with cellulose in their cell walls and chlorophyll A and B in their chloroplasts.

Closest Relatives to Land Plants

  • Charophytes and charaplants are identified as the closest relatives to land plants.

  • charophyte: first plant to colonize 500 mya

Benefits and Challenges of Life on Land

Benefits

  • More Co2 in atmosphere

  • unfiltered sunlight

  • Access to rich mineral soils.

Challenges

water scarcity and gravity

Adaptations to Life on Land

Cuticle

  • A waxy outer covering that prevent desiccation ( drying out).

Stomata

  • Specialized pores that allow gas exchange; Co2 in, o2 out, help regulate H2O reserve

Vascular Tissue

  • Specialized tissue that transport water and nutrients,

    (not all plants possess this).

Shared Derived Features of Land Plants

Alternation of Generations

plants alternate between multicellular haploid and multicellular diploid life stages

  1. sporophytes (2n) produces spores(n) through meiosis

  2. spores form gametophyte (n) through mitosis which in turn forms gametes (n) through mitosis

  3. gametes fuse to form 2n zygote and sporophyte

B. Mulicellular, dependent embryos:

  • Zygotes are retained (protected and nourished) within the tissues of the female gametophyte

    C. Spore walls made from pollenin

  • spores (n) covered in proctective sporopollenin polymer

  • spores generated by sporocytes (2n) inside sporangia

  • sporongia contains sporocyte (2n). These cells undergo meiosis to produce spores (n)

    D. Apical meristems

  • are the plant version of stem cells

  • they are regions of rapidly dividing cells

  • allows growth at the root and shoots ( ROOT MERISTEMS ALLOW PLANT TO OBTAIN H2O AND NUTRIENTS)

Features of Seedless Vascular Plants

  • Include structures to transport water and nutrients:

    • Xylem: Transports water and minerals from roots upwards. Composed of tracheids (dead cells).

    • Phloem: Transports sugars and amino acids (bi-directional).

Life Cycle of Mosses

  1. Dominant gametophyte is produced from spores that develop into protonema (filamentous structure).

  2. Male organs (antheridia) produce sperm; female organs (archegonia) produce eggs.

  3. Sperm swim through water to fertilize eggs within the archegonia.

  4. Fertilized zygote evolving into a sporophyte.

  5. Spores are produced by the sporophyte via meiosis in the sporangium.

Ferns Life Cycle

  1. Gametophyte is produced from dividing spores

  2. Antheridia produce sperm; archegonia produce eggs.

  3. Sperm swim through water to fertilize eggs in archegonia.

  4. Zygote develops within gametophyte tissues and transforms into sporophyte (dominant form).

  5. Spores form via meiosis within the sporangium of the sporophyte.

Main Groups/Lineages

  • Bryophytes: Include Hepatophytes (liverworts), Bryophyta (mosses), and Anthocerophyta (hornworts).

  • Seedless Vascular Plants: Include Lycophytes (Club mosses) and Monilophytes (ferns).