LO5

Describe the evolution, life cycles, and adaptations of land plants

all members of the archaeplastids

posses chloroplasts derived from primary endosymbiosis

plants are

archaeplastids

all members of the archaeplastids

posses chloroplasts derived from primary endosymbiosis

plants are

archaeplastids

land plants evolved from

multicellular aquatic green algae ancestor

similarities provide evidence of the close relationships between plants and green algae

DNA and use of the same photosynthetic pigment ( chlorophylls a & b, carotenoids)

What adaptations did plants evolve when they transitioned to land?

a waxy cuticle, stomata, and spore

A waxy Cuticle

covers the above-ground parts and prevents drying out

Stomata

allows for gas exchange on land; microscopic pores on leaves and stem that allow exchange of CO2 and O2

Spores

reproductive cell adapted for dispersal on land due to their tough outer coat ; produced in capsule-like structure called sporangia

Sporangia

capsule-like structure spores are produced in

Plants reproductive organs

multicellular, produce gametes, and protect the developing embryo

Archegonia

female reproductive organs, each produce a single egg, egg is fertilized within the archegonia and developed into an embryo that is protected within the archegonia

Antheridia

male reproductive organs, each produce many sperm

Plants have a life cycle referred to as

Alternation of generations life cycle

Alternations of generations life cycle

alternated between haploid and diploid generations

What does a Gametophyte plant produce ?

haploid, multicellular generation ; produces haploid gametes (sperm or egg) via mitosis in side reproductive organs ; gametes fuse (fertilization) to form diploid zygote

diploid zygote

formed when gametes fuse (fertilize) ; begins the next generation ; 1st stage of sporophyte generation

Sporophyte

diploid, multicellular generation ; has become increasingly dominant

Sporophyte generation

1) diploid zygote is the 1st stage, 2) zygote develops by mitosis into a multicellular embryo inside the archegonium, 3) embryo develops into mature sporophyte plant that produces haploid spores by meiosis inside sporangia, 4) the spore, the 1st stage of gametophyte generation, developed into haploid multicellular gametophyte plant via mitosis

How are main group of plants recognized?

based on the presence or absence of vascular tissue and seeds

tube cells that transport water and nutrients throughout plants, and provide structural support

What is the structure of vascular tissue in plants

a sporophyte embryo with nutrients inside of a protective coat

Seed

lack vascular tissue and seeds(bryophytes) and use spores for dispersal

Nonvascular plants

have vascular tissue

Vascular plants

have vascular tissue, lack seeds, and use spores for dispersal

Vascular seedless plants

produce spores, but use seeds for dispersal ; gymnosperms and angiosperms

Vascular plants (seed plants)

first plant to evolve and colonize land -450 mya

doesn’t have true leaves, stems, and roots and are small due to lack of vascular tissue

only plants to retain the ancestral train of dominant gametophytes

gametophyte plant is larger, lives longer, and protects and nourishes the sporophyte

retain ancestral trait of flagellated sperm that acquires external water to swim to the egg

Mosses are the most common

Non vascular plants(Bryophyte)

Mosses

What plant is the most common bryophyte, and has an ecological importance due to their root-like structure that prevents erosion and aid forming soil by secreting acids that break up rocks?

Most plants are

Vascular

dominate modern terrestrial ecosystems, form a monophyletic group, form true leaves, stems, and roots, and allow for larger size ; dominant sporophyte generation

Vascular plants characteristics

forms a paraphyletic group

bryophytes (nonvascular plants)

diploid, only sporophyte plants have vascular tissue

sporophyte plants advantage

What is the Gametophyte disadvantage?

may be dependent on the sporophyte plant for nutritions and protection

seedless, and became the dominant land plants (-350 mya) prior to the evolution of seed plants ; typically small (modern day)

The 1st seedless vascular plant

sporophyte is dominant, but gametophyte is independent (performs its own photosynthesis )

What generation is dominant in Seedless Vascular plants?

a fern is a sporophyte plant, and its gametophyte is a tiny, nonvascular, short-lived plant

seedless vascular plant example

typically restricted to moist terrestrial habitats because their bikont sperm require water to disperse the egg

similarities between bryophytes and seedless vascular plants

gymnosperms

first seed plants,(360 mya) ; evolved from ancient seedless Vascular plants ; sporophyte is even more dominants in seed plants; and microscopic gametophyte is dependent on sporophyte for nutrition and protection ; gametophyte is on cones in gymnosperms and within flowers on angiosperms ; produce spores but use seeds for dispersal

seeds (in seed plants)

have a tough puter coat, a food supply, and are multicellular

Seed plants

Heterosporous: produce two types of spores and Spores are not released from sporophyte parent

Female heterosporous spores

megaspores, are produced in megasporangia and develop into female gametophytes

Male spores

microspores, produced in microsporangia and develop into male gametophyte

necessary percursor of the evolution of seeds

Heterospory

megaspore remains in the megasporangium (ovule) as it develops into a female gametophyte. The female gametophyte produces an egg and grows into a new sporophyte if fertilized. The new sporophyte embryo+remaining female gametophyte tissue (food supply) + the outer layer of the megasporangium (seedcoat)= seed

entire female gametophyte generation develops within the parent sporophyte plant, and fertilization occurs within the sporophyte (Heterospory in female seed plants)

Heterospory in seed plants (male gametophytes)

male gametophytes are reduced to microscopic pollen grains; microspores develop into pollen grains inside the microsporangia. Pollen grains are dispersed (by wind or animals) to ovules during pollination. Each pollen grain produces a non-flagellate sperm that is transported to an egg for fertilization by a pollen tube. The pollen tube delivers the sperm to the egg, eliminating the need for flagella and external water

Where do the seeds on gymnosperm develop?

on the cones

How and why did the gymnosperms become the dominant plants on land?

when the climate became drier they outcompetes seedless vascular plants because they did not have to rely on external water to disperse their sperm, and because they disperse seeds

What plant is the most abundant gymnosperm?

conifers

conifers

ecologically important as habit for many organisms, food, and for the prevention of soil erosion

How do conifers prevent soil erosion ?

Their roots hold the soil in place

Term for the flowering plants

angiosperms

Which classification of plant evolved from ancient gymnosperms and have been the dominant plant for the past 90 mya?

angiosperms

How did angiosperm flowers evolved?

from the leaves to better falicitate reproduction

within a flower, how are angiosperm ovules protected?

inside of an ovary

What occurs once an angiosperm has reached fertilization?

an ovule becomes a seed and the ovary becomes a fruit

What is the fruits primary function in an angiosprm?

to protect the seed and aid in seed dispersal

What are the non-reproductive parts of a flower?

The outer parts. They protect the flower and attract pollinators(petals)

What do the inner parts on and angiosperm include?

male/ and or female reproductive organs

What does the ovary contain?

one or more ovules

What does the anthers contain ?

microsporangia that produce pollen grains

How many sperm does angiopollen graisn contain?

two sperm

What are the functions of the sperm in angiosperm pollen grains?

one fertilizes the egg the other fuses with two haploid nuclei

In the angiosperm pollen grain, what does the sperm that fertilizes the egg in an ovule form?

the sperm that fertilizes the egg forms a diploid zygote that develops into a sporophyte embryo inside the ovary

In the angiosperm pollen grain, what does the sperm that doesnt fertilize the egg form?

fuses with 2 haploid nuclei(in ovule) forming a triploid (3n) food supply that grows with the embreyo

What kind of fertilization does angiosperm have?

double fertilization

What kind of relationship do flowering plants and animal pollinators have?

mutually adapted to eachother

How did animal pollinated flowers evolve to attract specific animal pollinators?

evolved brightly colord petals, scent, and nectar

What are the advantages of asexual reproduction in angiosperms?

results in a rapid increase of offspring and offspring are initially more hardy than seeds

What are the advantages of sexual reproduction in angiosperms?

genetic diversity and dispersal of seed