Green algae & plants

What does green algae include?

species that are unicellular, colonial, or multicellular that live in freshwater and marine habitats

two lineages that green algae is hypothesized to be most closely related to land plants

coleochaetes, stoneworts

Three categories of plant phyla

Non-vascular, seedless, seed

Non-vascular plants (bryophytes)

lack vascular tissue, specialized groups of cells that conduct water or nutrients throughout the plant body (moss)

Seedless vascular plats

well-developed vascular tissues but do not make seeds, which consist of an embryo and a tone of nutritive tissue (ferns)

seed plants

have vascular tissue and make seeds (flowering plants)

Adaptations to solved the problem of water evaporation

Prevention of water loss from cells
Transportation of water from tissues with access to water to tissues without access

Why is growth on land adventageous

bc resources such as light and carbon dioxide are more plentiful

Cuticle

waxy, watertight sealant that covers the aboveground parts of the plant and gives them the ability to survive in dry environments (keeps necessary CO2 out)

Stoma

opening called a pore surrounded by specialized guard cells (gas exchange)

Importance of upright growth

better access to light (water agains gravity, susceptible to gravity and wind)

What did the evolution of vascular tissue allow early plants to do

transport water from roots to aboveground tissues and support erect stems

adaptation in upright growth

lignin- structural polymer, defining feature of vascular tissues, cell walls of water-conducting cells

How do plants reproduce in dry conditions?

tough coat of sporopollenin
Gametes that were produced in complex, multicellular structures
Embryos that were retained on and nourished by the parent plant

What reproductive organ did early land plants have

gametangia- protected gametes from drying out and damage (all plants except angiosperms)

Male vs female gametangia

sperm structure- antheridium
egg structure- archegonium

what do zygotes of all land plants do during the beginning of development?

form multicellular embryos that remain attached to and are nourished by the parent plant

Embryophyta

the retention of the embryo

transfer cells

land plant embryos which make physical contact with parental cells and facilitate the transfer of nutrients

What do all land plants undergo

alternation of generations

What happens in the alternation of generations

individuals have a multicellular haploid phase called the gametophyte and a multicellular diploid phase known as the sporophyte

Two types of spore-producing structures in heterosporous species

microsproangia and macrosporangia

Microsporangia

produce spores that develop into male gametophytes that produce sperm

Macrosporangia

produce megaspores that develop into female gametophytes that produce eggs

What are the gametophytes of seed plants

either male or female, but never both

pollen grain

in heterosporous seed plants, the microspore germinates to form a male gametophyte that is surrounded by a tough coat of sporopollenin

What happens when pollen evolved

heterosporous plants lost their dependence on water for fertilization

What is a seed

a structure that includes an embryo and a store of nutrients provided by the mother surrounded by a tough, protective coat, allows embryos to be dispersed to a new habitat

what are cones

in gynmosperms, the seperate structures where microsporangia and megaspronagia develop

Heterospory in gymnosperms

Microsporangia divide by mitosis to form pollen grains
Megasporangia divide by mitosis to form female gametophyte

What is the success of the angiosperms because of

the reproductive organ, the flower

Two reproductive structures of flowers

The stamen contains the anther, where microsporangia develop

The carpel contains the ovary in which the ovules are found (megasporangi)

Double fertilization

Involves two sperm cells
One sperm fuses with the egg to form the zygote while a second sperm fuses with the two nuclei in the female gametophyte to form a triploid (3n) endosperm

What do stamen and carpels become later

sepals and petals

Flowers may be adaptations to increase the probability that an animal will preform

pollination- the transfer of pollen from one individuals stamen to another individuals carpel

Two groups of angiosperm

monocots and dicots (divided based on differences in first leaves)

monocots vs dicots

monocots are monophyletic, dicots are paraphyletic

Green algae

paraphyletic group, double membrane chloroplasts, primary producers

Example of green algae

Ulva lactuca- sea grass

Non-vascular plants

gametophyte is the dominant phase of the life cycle, grow low to the ground, rhizoids which anchor to soil, require water for reproduction, spores are wind-dispersed

Example of non-vascular

hornworts, moss

Seedless vascular plants

paraphyletic group, all have vascular tissue with lignin cells, depend on water for reproduction, sporophyte is the dominant phase

Example of seedless vascular plants

ferns

Seed plants

monophyletic group, gymnosperms and angiosperms, produce seeds and pollen grains

Angiosperms

defining feature is the flower, animal pollinated flower has both pollen and eggs, wind-pollinated flower has separate male and female flowers