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What is a Eukaryote?
A eukaryote is membrane bound, has compartmentalisation, organelles, and a membrane bound nucleus.
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What was the key to eukaryotic innovation?
The nuclear envelope
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What is the Endosymbiosis Theory?
The Endosymbiosis Theory was explored by Lynn Margulis 30+ years ago. The idea she promoted was that the mitochondria was a bacterium that had been incorporated into an ancient eukaryotic history/lineage (Mutualism).
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Support for Endosymbiosis
- Mitochondria :
- are similar in size to bacteria
- reproduce by fission
- circular genome
- have own ribosomes
- translate proteins
- have a double membrane system
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Does endosymbiosis explain eukaryotes having chloroplasts too?
- Yes. Why?
- 1. Not all eukaryotes have them
- 2. In some groups of photosynthetic protists, there was a secondary endosymbiosis
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Where did secondary endosymbiosis first occur?
Secondary endosymbiosis first occured in green algae.
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Land plants are important because...
- main primary producers
- affect atmospheric gases
- stabilize soil conditions
- moderate local climate
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Tradition plant classification
nonvascular, seedless vascular and seed plants
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Examples of non vascular plants are:
liverworts, hornworts and mosses
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Characteristics of non vascular plants are:
- All non-vascular plants have a cuticle
- Liverworts have simple pores and protected embryos
- Hornworts and Mosses also have stomata
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Examples of seedless vascular plants are:
lycophytes, ferns and horsetails
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Characteristics of seedless vascular plants are:
- All: Trachieds and roots
- Lycophytes: addition of vascular tissue
- Horsetails and Ferns: true leaves
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Examples of seed plants are:
angiosperms and gymnosperms (conifers, cycads, gnetophytesm ginko)
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Characteristics of seed plants are:
SEEDS!
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Benefits of seeds and pollen are:
- Can tolerate drying
- Seeds are packaged with nutrients
- Not dependent on parent during fertilzation
- Heterospory: male and female parts/sporophye
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Barriers for plants making the move to land were:
- water loss
- gas exchange
- reproduction
- water and nutrients equisition and movement
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Solution for water loss:
Cuticle: a waxy protective layer
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Solution for gas exchange:
- First there were pores: openings in the cuticle
- Then there were stomata: pores with control (guard cells)
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Solution to reproduction barrier:
"Protected embryos": seeds
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What is the process of Alternation of Generations:
- Start: Gametophyte(multicellular haploid organism) n
- Mitosis
- Fertilization
- Mitosis
- Sporophyte(multicellular diploid organism) 2n
- Meiosis
- End: Mitosis (n)
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Solution for water and nutrient equisition and movement:
- Vascular tissue: xylem and phloem
- Roots
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Gymnosperms vs. Angiosperms
- Angiosperms have:
- triploid endosperm (double fertilization:2 male gametes/3 sets of chromosomes)
- flowers: DIVERSIFICATION
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