Slide 1

Plant Diversity and Life Cycles

Slide 2

5 derived characteristics in land plants (not in ancestors) Apical meristems localized areas of cell division in shoot & tips Alternation of generations separate slide Walled spores produced in sporangia tough wall resists drying 2n spore mother cells go through meiosis to produce 4 haploid spores Multicellular gametangia Archegonium (female) produces haploid egg & keeps it Antheridium (male) produces & releases sperm Multicellular, dependent embryos develop w/in archegonium from zygote Derive nutrition from female parent tissue with specialized placenta- like cells

Slide 3

2 more traits that evolved in many plant groups Cuticle Made of waxes on surface of epidermal cells Protection Secondary compounds Repel herbivores & parasites Absorb UV radiation Attract symbionts

Slide 4

Basic Life Cycle of Plants Alternation of Generations

Slide 5

4 Major Plant Phyla 1.Bryophytes 2.Pterophytes 3.Gymnosperms 4.Angiosperms nonvascular plants Bryophytes (mosses) Land plants vascular plants Seedless Pterophytes (ferns, etc) Seed plants Naked seeds Gymnosperms Coniferophyta Enclosed seeeds Angiosperms Anthyophyta

Slide 6

Bryophytes Non-vascular whole body can absorb water Gametophyte is larger (dominant) stage Sporophyte dependent on gametophyte No true leaves Flagellated sperm Mosses require water for fertilization. Why?

Slide 7

Moss Life Cycle p. 581

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Pterophytes Seedless vascular plants Ex ferns Sporophyte larger stage True roots & leaves w/ horizontal stem Sporangia on leaves called sporophylls Homosporous one kind of spore (bisexual gamete egg & sperm) Heterosporous female spore (megaspore) female gametophyte egg Male spore (microspore)male gametophyte sperm

Slide 9

Fern Life Cycle p. 585

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Vascular Seed Plants Common traits Seeds Integument seed coat Female gametophyte food supply Embryo sporophyte baby plant Advantage of seeds Consists of embryo and food supply contained in protective coat Better resist harsh environments Disperse offspring more widely

Slide 11

Reduced gametophytes spores retained in sporangia, develop into gametophytes Heterospory Megasporangium produce one megaspore & female gametophyte Microsporangium produce many microspores & male gametophytes Ovules contains female gametophytes Pollen contain male gametophytes transferred to female part of plant and will germinate into a pollen tube that finds the ovule and egg

Slide 12

Gymnosperms Bear naked cones seeds are exposed on modified leaves that usually form cones Pollen cones produce pollen Ovulate cones produce eggs Coniferophyta pines, firs, redwoods

Slide 13

Pine Life Cycle p. 597

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Angiosperms Anthophyta - Flowering plants used for sexual reproduction Megasporangium megaspore megagametophyte in ovule (all enclosed in ovary of flower) Microsporangium microspore microgametophyte in anther of flower Fruits - mature ovary seed develops from ovules after fertilization, the wall of the ovary thickens Ex tomato, grapefruit, nectarine, milkweed, walnut Pollination required for transfer of pollen from flower to the female sex organs of another flower

Slide 15

Double Fertilzation One sperm fertilizes the egg cell and the other sperm combines with the two polar nuclei of the large central cell of the embryo sac. Result - One sperm nucleus unites with the egg to form the diploid zygote, from which the embryo develops, and the other unites with two polar nuclei to form the triploid, primary endosperm nucleus (nutrition).

Slide 16

Flower anatomy

Slide 17

Angiosperms

Slide 18

Seeds monocots & dicots DICOT MONOCOT

Slide 19

Germination 1. Imbibation taking in H2O 2. ABA decreases (plant soluble hormone that causes dormancy) 3. Embryo responds and releases gibberellin (stimulates release of amylase) 4. Amylase breaks down starch for nutrition which allows for growth 5. Root extends downward while shoot extends upward

Slide 20

Factors affecting germination HOW? Water Oxygen Temperature Light