Seed Plants

Chapter 30

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Seed Plants

Gymnosperms vs Angiosperms

Gymnosperms 3 Major evolutionary changes in gymnosperms

Further decrease in prominence of the gametophyte generation

Pollination Evolution of the seed

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5 Crucial Seed Plant Adaptations

1. Reduced gametophyte Now gametophyte is dependent on sporophyte Unlike in ________, where ________________

2. Heterospores Megaspores = produce female gametophyte eggs Microspores = produce male gametophyte sperm

3. Ovules and production of eggs Protection of egg and developing zygote Increases reproductive fitness (likelihood of successful

production of offspring)

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4 & 5 Crucial Adaptations

4. Pollen & sperm production Pollen grain contains sperm nuclei Pollen grain has waterproof coating No more water needed for sperm to travel to the egg

Now it is the wind that disperses sperm

5. Seeds Seeds > spores

Multicellular Layers of protective tissue Stored energy for the development of the embryo

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Ovule to Seed

Megaspore = Female spore (heterosporous) -- Megaspore female gametophyte -- Female gametophyte produces egg (n) -- Female gametophyte becomes nutrition for developing embryo

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Gymnosperms

“naked” seeds Not enclosed in ovaries (fruits) Seeds are typically in cones that

allow for airborne dispersal

Conifers (Coniferophyta) Pines, spruces, firs, and redwoods

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Conifers have Ovulate & Pollen cones

Megasporangium undergoes meiosis = 4 haploid cells, but only 1 becomes megaspore

Multiple archegonia are produced inside each gametophyte = multiple eggs produced

Only 1 fertilized egg develops into the embryo, others dissolve

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Gymnosperm Life Cycle Notes

Megasporangium (2n) – produces 4 megaspores (n) Via meiosis 3 spores (n) dissolve leaving 1 megaspore

Megaspore (n) – develops into the female gametophyte (n) Female gametophyte contains multiple archegonia Multiple egg production

Sperm nuclei from pollen fertilizes egg(s) Only one fertilized egg is able to survive

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Questions?

What is the correct term for the pine tree? Diploid or haploid?

What is the correct term for the cones on the pine tree? Diploid or haploid?

Yellow cones are_______, pine cones are _______

How is the pollen dispersed?

What does the pollen produce?

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What becomes of … ?

Megasporangium?

Megaspore?

Egg, if fertilized?

Ovule?

Female gametophyte?

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Angiosperms

Fruits, Flowers, and double Fertilization

90% of all plant species

Seeded + Vascular

Flower – structure for sexual reproduction

Fruits – mature plant ovaries (yes, you are eating plant ovaries)

Double fertilization 1 sperm fertilizes egg = zygote 1 sperm combines with 2 nuclei in ovule = endosperm

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Angiosperms – 2 classes

Monocots Monocots have 1 cotyledon (structure that

nourishes the developing plant) Parallel veination in leaves Orchids, lillies, and grasses

Dicots (Eudicots) 2 cotyledons in the seed Netted veination in leaves Roses, peas, beans, oaks

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Stamen = Male -- Anther + filament -- Microspores produced in anther

Carpel = female -- Ovary -- Stigma, style -- Megaspores produced in Ovules inside Ovary

Petals – attract pollinators

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Fruits -- Can be wet or dry

-- Wet fruits – oranges, plums, grapefruit, tomatoes

-- Dry fruits – Beans, nuts, & grains

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Life Cycle Notes

Male gametophytes and are inside pollen grains

Microspore pollen grain (n)

No real antheridia to speak of

Megasporangia produce megaspores (n) female gametophyte eggs ‘n stuff

Double fertilization After male gametophyte produces pollen tube 1 nuclei fertilizes egg cell = zygote 1 nuclei fertilizes 2 nuclei in ovule = 3n endosperm