algae

algae

  • algae - plant or protist kingdom?

  • photosynthetic members of kingdom protista

  • may be unicellular/multicellular

  • only other kingdom that contains multicellular photosynthetic members is the plant kingdom

  • confusion to whether green algae is in the plant or protist kingdom

  • plants evolved from algae, green algae are its evolutionary link

  • unicellular algae

  • all plant like protists are algae

  • three phlya to represent groups of unicellular plant like protists are: diatoms, dinoflagellates euglenoids

  • multicellular algae

  • seaweeds

  • three main groups based on colour: brown, red, green

  • brown algae

  • tall, most complex protists

  • key component to marine and tidal environments

  • structure: holdfast, stipe, leaf-like blades

  • ex: kelp, rockweed

  • red algae

  • first multicellular organisms on earth

  • live in warm waters

  • contain green chlorophyll

  • contain pigment called phycoerythrin

  • are a source of food

  • ex: dulse

  • green algae

  • aquatic, mostly in freshwater but can be in salt water

  • structurally diverse, can be unicellular or multicellular

  • very similar to plants: same types of chlorophyll, colour, cell walls contain cellulose, store food reserves in form of starch

  • ancestor of plants similar to green algae

  • ex: chlamydomonas, spirogyra

  • shift to land

  • green algae and plants have chlorophylls a and b in their cells

  • both have cellulose cell walls

  • both store food energy in form of starch

  • DNA analysis shows similar sequences

  • adaption to life on land

  • what changes would algae have to make to survive on land?

  • protection from drying out

  • system to transport water and susbstances from environment to cells within plant body

  • system to support body of plant, lifting it into the light and air

  • how plants adapted to life on land:

  • plant reproduce using embryos

  • vascular tissue, leaves and roots

    • consists of two types of vascular tissue: xylem and phloem

    • xylem: dead tube-shaped cell with tough material called lignin which allows minerals and water to be transported thru plant

    • phloem: tube tissue made of living cells that transport larger molecules such as sugars

    • vascular tissues allowed for the evolution of roots and leaves

    • leaves allow for better exchange of gases in photosynthesis and larger surface area for capturing sunlight

  • plants and some green algae use sporic reproduction (alternation of generations)

    • generations alternate between haploid and diploid stage

    • gametophyte (haploid) produces gametes by mitosis

    • gametes fuse to form a diploid zygote, which then develops into the sporophyte (diploid)

    • The sporophyte produces spores by meiosis, which grow into haploid gametophytes.

  • significant developments in evolution of land plants include

    • production of embryos

    • development of vascular tissue

    • production of seeds

    • production of flowers