BIOL 1030 Lecture Notes - Lecture 22: Coevolution, Lycopodiopsida, Multicellular Organism
7 May 2018
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BIOLOGY 1030 - KEVIN SCOTT and CARLA ZELMER - WINTER 2018 - Lectures 22-26!
Lecture 22: Introduction to Land Plants
Bryophytes: small plants needing to be close to water (Liverworts)!
"Vascular plants (Tracheophytes): have one phase with vascular tissue, is a water-
conducting plant. !
"Evolved from aquatic green algae, based on fossil records; cellulose cell walls, starch,
photosynthetic pigments (chlorophyll a, b and carotenoids), molecular systematics (DNA,
coding for pigments).!
"Charophytes are the ancestors, aquatic green algae. !
Land Plants:!
1. Haplo-diplontic life cycle (sporophyte 2n, gametophyte n)
Sporophyte: Multicellular and diploid phase, derived from zygote by mitosis!
"Life cycle function: within sporangia (diploid), sporophyte cells undergo meiosis to
become spores!
Gametophyte: Multicellular and haploid stage, derived by mitosis from a haploid
‘spore’. Spores germinate to produce a multicellular phase, the gametophyte.
"Life cycle function: within gametangia produce gametes, these are produced by mitosis!
"Egg, archegonia (female gametangia): egg cells are produced by mitosis!
"!
"Antheridia (male gametangia) : sperm are produced by mitosis!
"Production of gametes is separated by time as to avoid self-fertilization and free-water
is required for dispersal (restriction to certain areas).!
2. Oogamy: differentiation into male and female gametes
•Production of a large, non-motile gamete (egg) and a small, sperm cell that is motile.
•Sperm are transported by 2 modes of transportation (primitive, Bryophytes and Ferns)
-By water: flagellated sperm
-By pollen tube: advanced, also seen in seed plants
-Production of pollen in the male gametophyte, developing into a pollen tube to fertilize
the egg.
•Syngamy (fertilization): occurs within the archegonium (within the female)
•Zygote: grows in the archegonium, female retains the zygote, zygote divides by mitosis to
develop into a multicellular organism, receives nutrients (via placenta), and protection from
parental plant.
•
3. Apical meristems:
-Localized regions of cell growth
-Divide to produce new tissue by mitosis:
•Vascular plants (ferns, seed plants):
-Sporophyte: RAM and SAM
-Bryophyte: Thallus, and lacks roots, stems, and leaves.
find more resources at oneclass.com
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Lecture 23: The Bryophytes
6 main traits of bryophytes
I. Life cycle has dominant gametophyte phase!
II. No xylem or phloem!
III. No roots (limited to live close to water)!
IV. No leaves!
V. No cuticle (no resistance to water loss)!
VI. Sporophyte is dependent on the female gametophyte for nutrition, this stage is short-lived!
"Polytrichum haircap moss thallus:!
Entire thallus can absorb water, minerals, have gas exchange and undergo photosynthesis!
"Mature Sporophyte:!
-Foot: receives nutrients transported from the female gametophyte!
-Seta: elongated stalk that raises up spore bearing capsule for dispersal!
-Sporangium: site of meiosis; where a young sporophyte cell (2n) becomes spores (n).!
"Under cap: peristome, open and closes with humidity to disperse and dispense spores,
wind is good. The spore giving rise to a new (n) phase.!
Dioecious - 2 houses, male gametes and female gametes; separate male and female plant
gametophytes.!
Gametophore: sexually mature gametophyte!
Gamete transfer occurs with motile sperm transported to the archegonium by water (down
the neck, to the venter, to the egg cell (archegonia)!
"Bryophytes:
-Life cycle is restricted to moist habitats because of a lack of cuticle and roots, and water
required for gamete transfer.!
-Adapted to land but only in wet or seasonally wet environments!
"!
"Lichens: associated with bryophytes (often in harsh environments), where there is no
way to sexually reproduce both symbionts at the same time!
A symbiotic relationship with!
-Fungal mycelium: hyphae, rep. disc, injected historia; soredia (packed for environment),
producing unique compounds!
-Algal cells:!
-Can break down rock and are important first colonizers and soil builders!
Ex: Thalloid (crustose) lichen to rock/foliose to leafy/fructose to reindeer moss, fungi is high in
protein!
!
Lecture 24: Vascular Plants
Seedless vascular plant!
•Lycophytes (club ‘moss’)!
•Pterophytes (ferns)!
Seed plants!
•Gymnosperms (spruces)!
•Angiosperms (orchids)!
find more resources at oneclass.com
find more resources at oneclass.com
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Document Summary
Biology 1030 - kevin scott and carla zelmer - winter 2018 - lectures 22-26. Bryophytes: small plants needing to be close to water (liverworts) Vascular plants (tracheophytes): have one phase with vascular tissue, is a water- conducting plant. photosynthetic pigments (chlorophyll a, b and carotenoids), molecular systematics (dna, coding for pigments). Evolved from aquatic green algae, based on fossil records; cellulose cell walls, starch, Land plants: haplo-diplontic life cycle (sporophyte 2n, gametophyte n) Sporophyte: multicellular and diploid phase, derived from zygote by mitosis. Life cycle function: within sporangia (diploid), sporophyte cells undergo meiosis to become spores. Gametophyte: multicellular and haploid stage, derived by mitosis from a haploid. Spores germinate to produce a multicellular phase, the gametophyte. Life cycle function: within gametangia produce gametes, these are produced by mitosis. Egg, archegonia (female gametangia): egg cells are produced by mitosis. Antheridia (male gametangia) : sperm are produced by mitosis. By pollen tube: advanced, also seen in seed plants.
