Nov. 4th Notes - Seedless Vascular Plants: Seed Plants And Gymnosperms Professor Folwer PDF

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Seedless Vascular Plants:
Seed Plants
And Gymnosperms
Professor Folwer...

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Nov. 4th NOTES Seedless Vascular Plants: Seed Plants And Gymnosperms RED = Vascular System Regional Specialization: - Shoot and Root (divised by the ground) - Shoot = height for light, they are trying to out-compete other plants for light. Light harvests leaves for itself, but also shades out other plants - Root = explore and exploit the soil. Detect nutrients to harvest them. Structural Support! Apical Meristems: generating roots and shoots - Localized region specialized for mitosis Two Extant Phyla of Seedless Vascular Plants: - 1. Lycophyta (club mosses- NOT mosses) - Oldest group - 2. Monilophyta: horsetails and ferns LIFE CYCLE: 1. Gametophyte is bisexual (ability to generate both eggs and sperm) (n) 2. Zygote is created via fertilization (2n) 3. Dominant Sporophyte (2n) seedling fern, is only supported by gametophyte for so long 4. Sporangia on underside of fern, where meiosis occurs to create spores (n) 5. Spores which grow to create gametophyte (haploid cells have half as many cells as diploid cells, therefore gametophytes have less DNA than sporophyte cells) Seedless Vascular Plants have a Sporophyte Dominant life Cycle: - Advantages: - diploid = genetic backup; two of each chromosome → reduces effects of ‘bad’ mutations - ALSO: collect mutations - more variation. More variation is a good thing.

SEEDS: - 305 mya - Very successful in living world now 1. Reduction of gametophyte - Bryophytes = dominant gametophyte - Ferns = free-living gametophyte - Seed Plants = female gametophyte retained in sporophyte (Advantages : female

gametophyte is completely protected and nourished) -

Vascular Plants may be either: Homosporous: one type of spore. (Bisexual gametophyte. Eggs and Sperms. Most seedless vascular plants. ) Heterosporous: two types of spores: - Megaspore (female gametophyte = makes egg) - Microspore (male gametophyte (pollen) sperm) - SEED PLANTS

2. Pollen: male gametophyte of seed plants - functionL deliver sperm - Most with NO FLAGELLA - Dispersed by water, wind, animals (advantage to just water) - Final sperm delivery via pollen tube - Pollen coat contains sporopollenin (chemical) which is component of spore walls and pollen. 3. Seeds improved the ability to disperse offspring: - Seeds are more resistant than spores - Multicellular (vs. single cell spore) - Contain: - 1. Embryo - 2. Stored Food - 3. Seed Coat (integument) Sporophytes of seed plants do not release their megaspores: - Remain in sporangium - Gametophyte develops inside the sporangium - (ovule) - 3 parts to ovule: integument (2n), Sporangium (2n), Megaspore (n). - Megaspore goes through mitosis and makes the egg THROUGH MITOSIS - Megagametophyte (n) and egg (n) - Micropyle = opening (to receive sperm into ovule) A fertilized ovule develops into a pine seed - Three generations of a plant in sporangium 1. Gametophyte left over = food 2. Integument = seed coat 3. Embryo = megaspore which grows to megagametophyte

SIGNIFICANCE OF SEEDS: 1. Resistance to very harsh environments

2. Provides Dormancy (you can keep it for a long time) for less favorable seasons 3. dispersal 4. Food for young plant 5. Food for animals 6. Agriculture (savings seeds and collecting/planting the best ones makes for farming) Gymnosperms: - Have seeds - Earliest seed plants - 305 mya - “Naked seeds” - ovules not in ovaries - Replaced lycophyte and monilophyte forests (no longer just giant fern forest) - 4 phyla: - 1. Cycadophyta - 2. Gnetophyta - Ginkgophyta - Coniferophyta (need to know the underlined ones) - ALL MONOPHYLETIC! Phylum Coniferophyta: - Reproductive structures are in cones - Largest group of gymnosperms - (coast redwood, douglas fir) - Ovulate cone and pollen cone (wind pollinated)...