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Home , Megaspore, Microspore

Chapter 24: The Sex Life of ... Reproduction and Development • Plants can reproduce either sexually or asexually

 Asexual: Single plant →new plant ( genetically identical )  Daffodil ; Strawberry runners

 Sexual: Parental plants → new plant ( genetic mix )  Most plants

Asexual reproduction Sexual reproduction

Seedless navel Strawberry runners oranges pods

Alternation of Generations: Non-flowering The Sex Life of Plants... 1) Diploid adult ( - (2n)) • Produce ( - (1n)) • Plant sexual life history is complex:  Alternation of Generations: Spores germinate  Diploid (2n) plants alternate with haploid (1n) plants

2) Haploid adult ( - (1n)) • Produce gametes ( - (1n)) (Figure 43.2) Gametes Join (Zygote - 2n)

Page 1 1 Alternation of Generations: (Figure 43.4) : sporophyte & gametophyte Flowering Plants

Gametophytes do not live independently of the

Flower = Reproductive Structure Sporophyte Gametophyte • (1n) → sac (female gametophyte) • (1n) → grain (male gametophyte) • Seed = Zygote (2n)

Angiosperms: sporophyte & gametophyte Non-flowering vs. flowering plants : Male & female Non-flowering Flowering Ferns, moss, horsetails All angiosperms

Gametophyte lives Gametophyte are dependent independent of the sporophyte on the sporophyte Pollen &

Sporophyte

Male pollen Female ovules

The : Parts of a Complete Flower: Flowers are modified 1) Incomplete Flower: • A sexual display that enhances reproductive success • Base of flower; usually green • Protect flower during development Lack 1 or more  Entices animals to carry pollen to distant plants flower parts  Efficient (unlike wind…) 2) • Advertise flower location (bright / fragrant) • Evolutionary events: 3) 1) : attractant (sugary secretions) • male reproductive structure 2) Advertisement = Flashy flowers • Filiment = Support stalk • = Insects (bees, flies) , hummingbirds, mammals (bats) • Anther = Pollen production 4) Carpels • female reproductive structure • = Pollen capture • Style = Support stalk (Figure 24.4) • = Egg production

Page 2 2 Sepals Petals Monocots Dicots

Stamen carpels

• Male reproductive parts • Female reproductive parts.

Zuccinis Complete or incomplete? Incomplete flowers : what is missing from each?

Male Female

Page 3 3 Gametophyte Development: (MMC) Pollen: (MMC) 1) Pollen sac contains microspore mother cells

2) MMCs (2n) produce (1n)

3) Microspores (1n) form pollen grains:

• Tube cell • cells (1n)  Tough shell

Gametophyte Development: & Embryo Sac: (MgMC) Fertilization: 1) Ovules form in ovary

2) contains 1) Pollen lands on stigma A) Integuments (outer layers) B) Megaspore mother cell 2) Tube cell (pollen) elongates to ovule (ovary) 3) MgMC (2n) produces (1n) 3) Sperm (via tube) : 4) Megaspore divides to A) fertilize egg (2n) form embryo sac B) fertilize central cell (3n) • egg (1n) • • central cell (2n) • Food Storage

(MgMC) Pollination = Pollen grain lands on stigma Fertilization = Fusion of sperm and egg (Figure 24.9)

Seed / Development: Fruit or vegetable? 1) Petals / shrivel & fall away • Fruits are the maturing ovary of a plant. 2) Fruit enlarges: Many vegetables are also fruits! • Ovule integuments → seed coat • Endosperm absorbs nutrients from parent

3) Zygote develops into embryo (cotelydons) • Dicots: Completely absorb endosperm • Monocots: Partially absorb endosperm • Fruit body = Ovary wall • Aid in

Page 4 4 : Monocot Germination: stay dormant until germination signaled: 1) Drying: Seed must dry out • Seed doesn’t germinate in fruit

2) Cold: Seed must be exposed to prolong cold period • Seed doesn’t germinate in winter

3) Seed Coat Disruption: Seed must have coat broken • Seed doesn’t germinate off periods (e.g. dry) Germination Events: 1) emerge (gather water / minerals)

2) push through to surface • Monocots: Coleoptile protects apical (Figure 24.12a)

Germination: Dicot Germination: Seeds stay dormant until germination signaled: 1) Drying: Seed must dry out • Seed doesn’t germinate in fruit

2) Cold: Seed must be exposed to prolong cold period • Seed doesn’t germinate in winter

3) Seed Coat Disruption: Seed must have coat broken • Seed doesn’t germinate off periods (e.g. dry) Germination Events: 1) Roots emerge (gather water / minerals) 2) Shoots push through to surface • Monocots: Coleoptile protects apical meristem • Dicots: Stem bends into hook (Figure 24.12b)

Germination: Adaptations for Pollination: Seeds stay dormant until germination signaled: 1) Drying: Seed must dry out Coevolution matches Plants and Pollinators: • Seed doesn’t germinate in fruit Coevolution = One species acts as major force driving the 2) Cold: Seed must be exposed to prolong cold period evolution of another species • Seed doesn’t germinate in winter Flowers: Attract pollinators / detract unwanted visitors 3) Seed Coat Disruption: Seed must have coat broken Pollinators: Identify / locate useful flowers & extract nectar • Seed doesn’t germinate off periods (e.g. dry) Sometimes coevolution is so specialized that a Germination Events: single flower species will attract only one . 1) Roots emerge (gather water / minerals) If one goes extinct, the other follows. 2) Shoots push through to surface Especially true with orchids • Monocots: Coleoptile protects apical meristem • Dicots: Stem bends into hook 3) Cotyledons nourish sprouting seed

Page 5 5 Types of Benefits: Types of Benefits: 1) Flowers Offer Food for Pollinators: 2) Flowers Offer ‘Sex’:

Nectar - Insects Nectar - Birds Nectar - Mammals

Pollinators locate flowers via:

The Birds and the Bees? Vision (Ultraviolet) Fly Orchid ‘Confused’ Wasp Odor

Types of Benefits: Seed Dispersal: 3) Flowers Offer Nurseries: • Important so young don’t compete w/ adult • Seed dispersal is function of fruit Approaches for Seed Dispersal: 1) Shotgun Dispersal: • Seeds explosively ejected from fruit (e.g. mistletoe) 2) Wind Dispersal: • Lightweight fruits carried by wind

Maple Seeds Yucca Yucca Moth Dandelion

Approaches for Seed Dispersal: 3) Water Dispersal: • Seeds float on water 4) Animal Dispersal: • Cling to fur • Eaten and passed Coconuts

Cocklebur Bat

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