Chpt. 30 Evolution of Seed Plants

Seed Plants Gymnosperms – naked seedsGymnosperms – naked seeds Angiosperms – covered seedsAngiosperms – covered seeds

Life Cycle switch

Further Reduction in Gametophyte generation N

What is the trend???? Seed Plants:  gametophyte is surrounded by SPOROPHYTE  gametophyte nourished by sporophyte.  no water needed

What is the trend???? Seed Plants:  no environmental stress for the gametophyte.  no spores produced.  microscopic

Multi-cellular sporophyte embryo w/ a food supply

Origin of seeds:

First seed plants Gymnosperm: conifers –vascular –heterospory male vs. female gametophytes –seeds naked seeds (no fruit) –pollen contain male gametophyte –life cycle dominated by sporophyte stage coniferous trees you are familiar with are diploid –gametes protected from drought & UV radiation

Gymnosperm: conifers

Cones & naked seeds

male female sporangium & pollen pine embryo

Origin of angiosperms (flowering plants)

Flower Variations Perfect Flowers - have stamens and carpels.Perfect Flowers - have stamens and carpels. Imperfect Flowers - have stamens or carpels.Imperfect Flowers - have stamens or carpels. Staminate FlowerCarpellate Flower

SPOROPHY TE 2n

in anther : microspores form via. meiosis…

in ovary : Megaspores form, in the ovule, via. meiosis

in anther : microspores develop into male gametophytes which are pollen grains

MATURE POLLEN GRAIN Specialize cell wall outside Inside :Tube Nucleus (cell) : Generative Nucleus (cell) will divide and produce two sperm nuclei

pollen grains produce two cell types: sperm cells (2) pollen tube generative cell = tube cell =

in ovary : Megaspores form female gametophyte found in the ovule

Where does the female gametophyte develope Tissue that protects sporangium Area that gives rise to female gametophyte Develops into female gametophyte OVULE

Megaspore- inside ovule undergoes meiosis.

Megaspore nucleus- inside ovule then divides 3X mitotically:

produces a sac with 8 nuclei Multicellular gametophyte

1 egg cell 2 polar nuclei 5 others Multicellular gametophyte

1 X 2 X 3 X megasporesurviving mitosis eggpolar nuclei others

Pollen attaches to the stigma & pollen tube develops

Pollen Vectors Bees Flies Butterflies Moths Birds Beetles Bats Wind

fertilization

how fertilization????

2 sperm fertilization into embryo sac

 * * double fertilization creates: endosperm & zygote

What happens after fertilization?

germination

D R O P in CO 2 -->

Cooler temps

Summary  Know the adaptations of seed plants.  Know examples, life cycles, and importances of the gymnosperms and angiosperms.

Any Questions??

Nonrenewabl e

mature sporophyte l two types of cones these hold the sporangi a

monoecio us = both sexes on one plant

(sporophyte) cones are clusters of sporophylls - “leaflike” structures

(sporophyte) meiosis - > produce haploid microspores… pollen

(sporophyte) Sporophyll - “leaflike” structures Pollen - inside sporphyll

(sporophyte) pollen Microsporangia -----> meiosis--> microgametophyte ---> pollen

Megaspore --> found inside scales.

Megaspore --> produces egg

egg Magasporangia ----> meiosis --> megaspores ---> egg

opening Pollination through micropyle

Meiosis produces 4 haploid cells. ONE becomes megaspore. This will become gametophyte

Archegonia develop (within gametophyte)

Sperm develops in the pollen, pollen tube extends to the gametophyte --> FERTILIZATION

` embryo forms … Sporophyte