Lab 6: Green Algae and Seedless Plant Diversity

Green Algae

A group of photosynthetic organisms that are not land plants, eukaryotic, most are protists, contain chlorophyll for photosynthesis, can be uni or multicellular, primarily aquatic, and fall into the charophyte group.

Plants

Photosynthetic organisms that have complex tissues evolved for living on land that are eukaryotic, photosynthetic, multicellular, and primarily terrestrial

Plants and Green Algae

Primary producers and autotrophs

Challenges preventing desiccation

Protective cuticle(waxy covering)

Challenge: support for body

Vascular tissues(roots absorb water and minerals, green shoots conduct photosynthesis)

Challenge: gas exchange

Stomata

Challenge: fertilization of gametes

Gametangia (protective gamete housing, antheridia for sperm and archegonia for eggs)

Diploid multicellular stage

Sporophyte generation

Haploid multicellular stage

Gametophyte generation

Sporophyte (2n)

A spore(n)is a haploid cell for asexual reproduction and a sporangium is the location of spore production in meiosis

Gametophyte(n)

Gametangia is the location of spore production by meiosis, antheridium(n) is the location of sperm production, and archegonium(n) is the location of egg production

Evidence chlarophytes are the closest relatives to terrestrial plants

Similar mechanisms for forming cell plates, similar nuclear and chloroplast genes, cell walls with high cellulose concentration, flagellated sperm similar to land plants, and the genus chara produce gametes within gametangia which was a key feature that allowed plants to colonize dry land.

Genus Spirogyra

Are haploid(n) and reproduce asexually under normal conditions, use sexual reproduction under deteriorated conditions via conjugation resulting in a zygospore(2n) with a thick coat

Conjugative filament phases

a) vegetative filament(n)

b) formation of conjugation tubes

c) gamete(n) from a filament migrate to the other

d)fusion of two gametes form a zygospore(2n)

Genus Chara

Reproduce via archegonium(contain eggs) and antheridium(contain sperm)

Bryophytes(mosses)

Seedless plants, reproduce with spores, earliest land plants, most abundant plant until 285 MYA, and many species are adapted to grow on rocks

Non vascular Bryophytes

Rely on diffusion and osmosis, anchored to rocks by rhizoids, gametophyte(n) is the dominant generation, depending on on gametophytes for energy and nutrition

Moss antheridium are located

At the top of the gametophyte(n) and contain sperm inside

Moss archegonium are located

At the top of the gametophyteand contain eggs inside

Moss capsule

Located at the top of the sporophyte(2n) and contains sporangium(2n)

Sporangium

2n

Spores

N

Ferns

Seedless vascular plants(contain roots, leaves, and stems, dominant generation is sporophyte(2n), both generations are free willing(neither depend on the other)

Gametophytes in ferns are

Reduced or smaller

What is on the underside of Fern fronds(leaves)

Sori

Sori

Contain sporangia where meiosis takes place to produce spores

Fern gametophyte contain

Male and female Gametangia

Both fern and moss sperm

Require a little bit of water to swim to the egg

What is this

Spirogyra

What is this

Chara

What is this

Spirogyra sexual reproduction

What is this

Chara reproduction

What is this

Male moss gametophyte

What is this

Female moss gametophyte

What is this

Moss capsule

What is a fern leaf

Sporophyte(2n)

What is this

Fern sporophyte

What is this

Fern gametophyte