Topic 13 Flashcards
Closest Living Relative of Plants and COmmon Traits
Charophytes Freshwater Green Algae, originating from a common ancestor of Clade
Streptophyta
Traits: circular protein rings embedded in plasma membrane to synthesize cellulose and flagellated sperm structure
Three possible “Plant” Kingdoms
Clade Streptophyta (green algae)
Clade Viridiplantae
Clade Embryophyta (closest to actual plants of Kingdom Plantae
Evolutionary Advantages of the Movement of Charophyte Ancestors to Land
Decreased Competition
Increased photosynthesis from brighter enviro
Abundant CO2
Rich Soil
Few herbivores/pathogens
Challenges for Charophytes moving to Land to Evolve into Plants
Scarcity of Water (desiccation)
Lack of structural Support
4 Adaptations of Charophytes Enabling Colonization of Land
- Sporopollenin
- Adaptations for Water Conservation
- Lignified vascular tissue for Internal Transport
- Functional compartmentalization in terrestrial plants
Sporopollenin
An adaptations that allowed charophytes to colonize land by charophyte zygotes being able to secrete sporopollenin, a durable polymer, in the cell wall to proect from desiccation, UV light, and physical stresses
Desiccation
Scarcity of water
Charophyte adaptations to Conserve Water
Waxy Cuticle as a protective layer
Stomata
5 Shared Traits of Plants
- Alternation of Generations
- Multicellular, dependent embryos,
- Wall spores produced in sporangia
- Apical meristems
- Cuticles
Steps to Alternation of Generations
Sporophyte (diploid, 2n) form from fusion of gametes (fertilization)
to
Sporophyte produce haploid spores via meiosis
to
Haploid gametophyte is specialized for fertilization and produces haploid gametes by mitosis
Apical Meristems
Regions of cell division at the shoot and root tips that enable continual group
Timeline of Plant Evolution
1.2 bya: Cyanobacteria and simple algae occupy terrestrial enviro
> 470 mya: earliest evidence of plant fossils
450 mya: fossilized spores appear
425 mya: larger plant structures appear in fossil record
