1041SCG Lecture Notes - Lecture 4: Non-Vascular Plant, Vascular Plant, Red Algae
19 Jun 2018
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1041SCG Biology Systems Notes
Weeks 4-5
No classes in week 4
Week 5 - 4th April
Evolution of Plants: Seedless Vascular Plants
Primary endosymbiosis produced the first photosynthetic eukaryotes
Evolution of chloroplasts was essential for photosynthetic pants to move onto land
Primary endosymbiosis is a shared derived trait of all plantae
Most recent closely related groups to red and green algae are the stoneworts
Synapomorphy: a characteristic present in an ancestral species and shared exclusively (in more
or less modified form) by its evolutionary descendants
Non-vascular pants: some have conduction cells but don’t have tracheids (male: 3 clades)
Vascular plants: well developed vascular systems with fluid conducting cells called tracheids
(female: 7 clades)
Embryophytes: any of a subkingdom (Embryophyta) of plants in which the embryo is retained
within maternal tissue and which include the bryophytes and tracheophytes
Tracheids: a type of water-conducting cell in the xylem which lacks holes in the cell wall
Land plants had to develop. They needed:
Transport systens for water and nutrients
Structural support
New ways to disperse gametes and progeny
Adaptions to dry conditions
Early algal groups (red algae) have chlorophyll A
Green algae and land plants have chlorophyll A and B (same as our land plants)
Vascular plants: well developed vascular systems with fluid conducting cells
Consists of a vascular system made of tissues specialised for transport of water and
materials from one part of the plant to another
Sporophyte of vascular plant is independent of the gametophyte at maturity
True roots and leaves developed in this group
Xylem: conducts water and minerals fro soil to aerial parts of the plant
Phloem: conducts products of photosynthesis (food) from production sites to use or storage sites
Non-Vascular Plants: liverworts, mosses, hornworts
Live in moist habitats, have thin cuticles
Mostly small, no vascular system to transport water so it is restricted in size
small enough that minerals can be distributed throughout their body via diffusion
Many have mutualistic association with fungi
In non-vascular plants: the gametophyte is photosynthetic (uses photosynthesis to carry out acts)
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Sporophyte is nutritional dependant on the gametophyte and remains attached to it
Games are produced in the gametangia (antheridia and archegonia)
Land plants had to develop. They needed:
Transport systems for water and nutrients
Structural support
New ways to disperse gametes
Adaptions to dry conditions
Evidence of adaption in plants:
Cuticle: waxy coating over leaves, slows water loss
Stomata: closable opening that regulate gas exchange and water loss
Gametangia: organs that enclose gametes to prevent them fro drying out
Embryos: young plants contained within a protective structure
Pigments: protect against UV radiation
Spores: thick was containing a polymer that prevents drying and resists decay
Week 5 - 5th April
Alteration of generations:
Multicellular diploid stage and a multicellular haploid stage
Spores develop into multicellular haploid organisms
Gametes produced by mitosis, spores produced by meiosis
Diploid zygote: developed by mitosis and cytokinesis into multicellular embryo and eventually a
mature diploid plant
This multicellular diploid plant is called the Sporophyte
Cells in the sporangia produce haploid spores by meiosis
Gametophyte: spores developed here, this is a multicellular haploid plant
Mosses have dominant gametophytes
Produces haploid gametes by mitosis
Fusion of gametes produces diploid zygote which develops into sporophyte
Tracheid: evolved in sporophytes and was critical for invasion of land
Lignin: provided structural support
Taller plants can intercell more sunlight and disperse spores more effectively
Vascular plants developed branching
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Evolution of chloroplasts was essential for photosynthetic pants to move onto land. Primary endosymbiosis is a shared derived trait of all plantae. Most recent closely related groups to red and green algae are the stoneworts. Synapomorphy: a characteristic present in an ancestral species and shared exclusively (in more or less modi ed form) by its evolutionary descendants. Non-vascular pants: some have conduction cells but don"t have tracheids (male: 3 clades) Vascular plants: well developed vascular systems with uid conducting cells called tracheids (female: 7 clades) Embryophytes: any of a subkingdom (embryophyta) of plants in which the embryo is retained within maternal tissue and which include the bryophytes and tracheophytes. Tracheids: a type of water-conducting cell in the xylem which lacks holes in the cell wall. Green algae and land plants have chlorophyll a and b (same as our land plants)
