Green Algae and Terrestrialization Flashcards
(37 cards)
The Chlorophyta and other plants share characteristics such as….
- Presence of chlorophyll a and b
- Identical type of chloroplast
- Presence of “plant” carotenoids such as beat-carotene, xanthophylls
- Cell walls containing cellulose
- Presence of starch within the chloroplasts
- Phragmoplast formation during cytokinesis
- Oogamy within a sporic life cycle (egg and sperm)
-Sporopollenin: a protective substance that covers spores and pollen grains
Non-embryophyte
Chlorophyta (green algae)
Embryophytes
Complex multicellular eukaryotes with specialized reproductive organs
Embryophytes (Non-vascular plants)
- Hepatophyta
- Anthocerophyta
- Bryophyta
Also called Bryophytes
Embryophytes (Vascular plant)
Pteridophyta
Also called tracheophytes
Embryophytes (Seed-bearing plants)
- Gymnospermophyta
- Angiospermophyta
Phylum Chlorophyta- Roles
- Primary producers
- Significant oxygenators
- Food energy source and source materials and vitamins for marine animals and human consumption, eg: Ulva, Caulerpa, Chlorella
- Mutualisms eg: lichens (w/fungi), zoochlorellae (Chlorohydra and certain flatworms)
- Important in building coral reefs and beaches: sand deposition, calcified species contribute to reef-building (mostly in the red algae)
- Niche (nesting sites) for many organisms especially reefs
- Bioindicators eg: warming of water bodies and polluting indicators
- Some species are used as biofuel eg: Chlorella, Scenedesmus, Sargassum
- The simplest eukaryotic autotrophs
- Classified as algae
Phylum Chlorophyta- Morphology
- Unicellular: motile and non-motile
- Colonial: motile and non-motile
- Filamentous: branched and unbranched
- Thalloid:
a) high SA:V ratio
b) passive transport mechanisms
c) no developed transport system (no xylem/phloem)
d) no cuticle (hydrocolloids in some)
e) no strengthening tissue
Phylum Chlorophyta-Microscopic forms
- Chlamydomonas
- Spirogyra
- Pediastrum
Phylum Chlorophyta-Macroscopic forms
- Sargassum
- Ulva
- Penicillus
Green Algae evolving towards terrestrialization have solved…
- Adaptations to living in a less dense medium—> anchorage and support
- Relatively limited water supply
- Relatively scarcity of minerals—> needed for rooting and absorption system
- Increased exposure to direct UV and cosmic rays (the sun)—> intensity and duration
- Adaptation to increased atmosphere
CO2—-> higher photosynthetic rates
*[CO2] is 2% that of atmospheric [CO2]
- Harmful effect of Reactive Oxygen Species (ROS) from increased O2 (from faster photosynthesis)
- Adaptation to pronounced fluctuations in ambient temperature
- Attacks from new and diversified microbes
Stages in Plant Terrestrialization
- Development of specialized cells/ organ diversification
- Accumulation of new (lipophillic) water-proofing compounds
- Modification of the life cycle
- Production of complex 2 (degree) compounds
- Establishment of mutualistic associations
- Removal of dependence on free water
Epidermis (Specialization)
- Maintains internal integrity
- Cuticle secretion
- Light transmission
- Root hairs
- Guard Cells
- Stomata
Mesophyll cells (Specialization)
- More chloroplasts per cell
- Bilateral symmetry
eg: palisade and spongy
Support (Specialization)
- Fibers
- Sclerenchyma
Vascularization (Specialization)
Water and food conducting cells
Also gives support
Storage tissue (Specialization)
- Roots
- Stems
- Leaves
Reproductive Organs (Specialization)
- Perennating organs
- Gametangia
- Sporangia
- Flowers
- Seed habit
(Lipophilic) Water-proofing compounds
a) Cuticle
b) Suberin
c) Cork
Complex 2 (degree) compounds
- Antioxidants
- Antimicrobials, eg. phenolics, terpenes, alkaloids etc.
Mutualistic Associations
- Pollination
- Dispersal Mechanisms
Dependence on free water is removed for….
- Support
- Reproduction
Characteristics of Plants
a) Traditionally regarded as mostly land-based “multicellular eukaryotic autotrophic organisms”
b) Traditionally classified into 2 large groups:
- Non-vascular or Vascular
- Spore-bearing and Seed-bearing (flowering) plants
c) Autotrophic
d) Pigmentation:
- light harvesting, photo-protection, antioxidants, attractants, precursors for plant growth substances (PGR’S)
- Chlorophylls a and b: main light-harvesting pigments
- Carotenoids: zeaxanthin, beta-carotene, beta-cryptoxanthin, lutein and astaxanthin
Plant Characteristics (Description)
- Shoot
- Root
make-up the plant body - Aquatic and terrestrial
- Growth patterns
- Movement
- Plant products: primary and secondary
- Growth form/Morphology- apical dominance
- Life cycle-alternation of generations
- The time taken for the completion of the life cycle; annuals, biennals and perennials
- Kingdoms are named on an ecological basis
