Plant Evolutionary Timeline Flashcards
What was the main hurdle plants had to overcome in order to successfully survive and breed on land?
When first online, gametes still needed water to reach each other. Plants were therefore not very good at surviving in areas that were not damp at the very least.
What is the dominant group of plants today?
Angiosperms (flowering plants)
In what era is life believed to have first arose? What is this life form a common ancestor of?
Archean; common ancestor of cyanobacteria.
What is the important event that took place during Archean period?
GREAT OXYGENATION EVENT creation of free oxygen in the atmosphere from the splitting of water for electrons in photosynthesis.
Why are cyanobacteria an important species in the evolutionary timeline?
Believed to be the ancestors of chloroplasts and mitochondria.
What plant types evolved in the Ediacaran period?
Red and green algae.
What happened in the Cambrian period? What happened specifically to plants?
Explosion of (mostly marine) life in the Cambrian period. Red and green algae came to the forefront as primary producers.
What are embryophytes?
Land plants
What plant is the ancestor of embryophytes?
Green algae.
What occurred in the ordovician period?
a few animals and plants began to explore the margins of the land (evidenced by spores) –> first embryophytes. Majority of life still confined to the seas.
The first spores that appeared in the Ordovician period resemble the spores of which primitive land plant?
The liverwort.
What is believed to be a possible cause of the Ordovician-Silurian mass extinction?
The consumption of CO2 by plants.
Which plants are Bryophytes?
Liverworts, hornworts and mosses.
Which plants evolved in the Silurian period? Which habitats do we see emerging?
Bryophytes diversified and the first lycophytes evolved. The first river and wetland habitats appear.
What are lycophytes?
Primitive vascular plants.
What physical adaptations have emerged by the end of the Silurian period? How do they help for life on land?
Branching - Enables some upward growth
Vasculature - Enables movement of water
Cuticle - Prevents desiccation
Stomata - Needed for gas exchange
What reproductive adaptations emerged by the end of the Silurian period?
Sporophyte becomes less dependent upon gametophyte and is moving towards dominance.
Identify which generation is n and which is 2n in plants.
n = gametophyte
2n = sporophyte
In which plants groups are gametophytes the dominant stage? Sporophytes?
Gametophytes = Bryophytes
Sporophyte = angiosperms and gymnosperms
What types of plants evolve in the Devonian period?
Lycophytes diversify, ferns, trees and seed plants appear.
What is important to note about the Devonian period?
Most adaptations required for life on land have appeared by the end of the devonian period.
What adaptations appear in the Devonian period? How are they important?
Roots - Movement of water and soluble resources, adds support
Lignin - adds support, waterproofing, protection
Seeds - protection
Secondary growth/vascular cambium - longevity, adaptability, increased size
Bark - protection
Differentiate between spores and seeds.
Spores = n; seeds = 2n
Seeds have seed coat to prevent desiccation and damage, enabling it to leave the plant. Spores do not leave sporangia.
Seeds contain resources to support young plant, spores do not.
What is the state of plants in the Carboniferous period?
“Go mad”.
Move into drier and previously inhospitable habitats
Get large
Grew and died at such a rate the eventually became coal.
