Green Algae and Terrestrialization Flashcards
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
Shoot
- Aerial
-Site for:
a) Photosynthesis
b) Gaseous exchange
c) Reproduction - Composition:
a) Main axis-support
b) Buds-growth and development; apical, axillary and flower
c) Branches
d) Leaves
e) Node and internode
f) Fruits and seeds
Root
- Subterranean
- Site for:
a) Absorption
b) Storage
c) Anchorage
d) Gaseous exchange
e) Reproduction - Composition:
a) Tap
b) Adventitious
c) Fibrous
Growth Patterns
a) Indeterminate
b) Meristematic
Indeterminate Growth
Growth that continues throughout the organism’s life without stopping
Meristematic Growth
The process of new cell growth in plants
Movement
a) Tropic
b) Nastic
Tropic Movement
The growth or movement of a plant in response to a stimulus in its environment
Nastic Movement
Non-growth or movement of a plant in response to a stimulus in its environment, though this depends on the direction of the stimulus
Primary plants
Mainly made up of primary tissues
Secondary plants
plants that grow after a disturbance, eg: natural event or human activity
Annuals
Plants complete life cycle in one year
Biennials
Plants complete life cycle in two years
Year One: Vegetative Structures
Year Two: Reproductive Structures
Perennials
Plants complete life cycle in more than two years
These plants are known for their ability to bloom repeatedly
