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Plants – The green algal ancestors of land plants, what plant
characteristics appeared in the green algae, and where they first appeared.
Two characteristics linked to modern day land plants and ancestral land plants are carbohydrate storage chlorophyll.
Green algae had chlorophyll A + B
Life cycle of plants. Major obstacles to living on land
- Gametangium Archegonium (female) and Antheridium (male)
- Sperm + Egg
Major obstacles to living on land.
- Sporophyte /Gametophyte
- Sperm and Spore
Periods - When different groups of land plants were most abundant and diverse.
- Most Diverse in Carboniferous
- First Vascular Plants
- Reproductive cycle of bryophytes
- Sporangium (tip)
- Sporocyte (operculum and peristone teeth)
- Archegonium (female) and Antheridium (male)
- Sperm + Egg
Mosses and liverworts compared. How bryophytes address the obstacles to livingon land. Ecological importance of bryophytes.
Structures of gametophyte and sporophyte.
- Either male or female depending on environment. Females only have sporophyte. Photosynthetic
- Rhizoids for attachment but not absorption. no vascular tissue.
- has "stem and leaves". Dominant plant
- SporophyteCompletely dependent on gametophyte
- Produces spores and dies.
Mosses and liverworts compared.
- Hepatophyta came first.
- Sporangium twist when they dry out and split open.
How bryophytes address the obstacles to living
- 1. Desiccation
- Gametophyte surive desiccation dormancy
Spores - water proof cell wall (sporopallenin)
- 2. Transportation
- Spores - wind
Ecological importance of bryophytes
Can grow on rocks. Important in succession. Hold rain water and release chemicals which promote weathering and collect dust particles which create soil for other plants to grow.
The first vascular plants - Structure and characteristics of the sporophyte.
- Stem only
- Dichotomous branching
- Part of stem on or underground (rhizome)
- Mycorrhizae to absorb water elements
- Sporangia at end of branches
Tissues of the sporophyte: their names, structures, and functions.
Specialized tissue and stem; epidermins is the outermost cell layer which have a waterproof cuticle, openings called stoma which contain guard cells.
- Vascular tissues: phloems: transport sugar
- Xylem: water + minerals
- Tracheids: have primary and secondary cell walls
- ligin in 2dary cell walls stiff to avoid collapsing
- Ground tissue
- Storage and photosynthesis
Sporophyte most dominant no fossil evidence due for gametophyte
Solutions to the obstacles to living on land.
- 2. Water Acquisition
- Rhizomes and mychorrizae
- 3. Internal Transport
- xylem and phloem
- Characteristics of homosporous and heterosporous life cycles
- Spores all the same
- Develop into a bisexual gametophyte that develops sperm and egg
- Heterosporousmicro and megaspores
The importance and potential benefits of heterospory.
Less inbreeding, greater genetic diversity and this happens because unisexual gametophytes
- Gametophytes can specialize
- males- produce/transport sperm
- females- support/protect young sporophyte
Characteristics of the sporophytes of Lycopodium and Selaginella, emphasizing new innovations of Lycopodiophyta.
True roots with root hairs
Leaves have microphyll (little leaves)
Strobilus (cone) cluster of sproangia which is partly attached to the leaf
Sporophyll - a leaf with a sporangium attached
Gametophte is small and simple and has no specialized tissue.
What “eusporangiate” and “leptosporangiate” mean
- parent cells are located at the surface of the tissue from which the sporangium is produced
- Arise from a single superficial initial cell
Which seedless plants are eusporangiate and which are leptosporangiate
- 1st vascular plants, lycopodiophta, horsetails, whisk ferns, eusporangiate ferns
- Most ferns
The evolutionary significance of the two kinds of plants.
- Gametophytes are relatively large
- Live multiple seasons
- Produce multiple sporophytes
- LeptosporangiateGametophytes are retalively small
- Live one season
- Produce on sporophyte
Fern life cycle.
- Most homosporous; some htersporous
- Sperm swim through water
Important features of ferns;gametophytes and sporophytes, origin of megaphylls.
Orginated from epidermis of microphyll
cluster of branches
Sporangia entirely on leaf
Evolutionary trends from bryophytes to leptosporangiate ferns.
- 1. Gametophyte
- Large (Bryophyte)>Small (Eusporangiate) >Smaller (Leptosporangiate)
- 2. Sporophyte
- Dependence on gametophyte
- 3. Water Acquistion
- Bryophytes (absorb rainwater)> Vascular plants (mycorrhizae)>Lycopodiophyta (roots)
- Bryophtes ("leaves")>Lycopodia (microphyll) > megaphyll (ferns)
Solutions of seedless plants to obstacles to land life: which plants solved them and how they they did so.
- 1. Desiccataion
- Gametophyte: Bryophytes
Sporophyte: Lycopodia (epidermis and cuticle)
Spores: Bryophytes (waterproof cell wall)
- 2. Water Acquisition
- Lycopodia (roots)
- 3.Internal Transport
- 1st vascular plants (xylem and phloem)
- 1st vascular plants (tracheids)
- 5. External transport
- Spores Bryophytes (wind)
The five shortcomings of seedless plants.
- 1. Sperm desiccation
- 2. Sperm transport
- 3. Gametophyte too small
- 4. Light competition
- 5. Space (disperal: sending spores out)
*NEEDS EXTENDED PERIOD OF APPROPRIATE ENVIRONMENT
- release spores
- spores grow into gametophyte
- eggs and sperm made
- young sporophyte
- new sporophyte
Gymnosperms- Reproductive cycle of gymnosperms
- Male Haploid
- immature microgametophyte (pollen)
- mature microgametophyte
- Female Haploid
- Male DiploidFertilization
- Microsporangiate Strobilus (pollen cone)
- Female Diploid
- Megasporangiate strobilus (ovulate cone)
What the important structures are