Principles of Phylogeny and Origins of Photosynthetic Life

know the structures of the cross section of a leaf, structure of stomata

What key adaptation permitted plants to colonize land?

Adapt to dry, high light conditions, develop transport systems for water and nutrients, develop structural support, and find new ways to disperse reproductive cells and progeny

What structures were formed as a key adaptation to colonize land?

Cuticle, spores, stomata, pigments, and a mutually beneficial association with fungi (mycorrhizae) that promotes nutrient uptake from the soil

What are cuticles?

A waxy coating that slows water loss

What are spores?

Feature thick sporopollenin walls that protect spores against drying out and decay (desiccation resistance)

What do stomata do?

Closable openings that regulate water vapor and CO2 going in and oxygen going out

What are the presence of spores in the sporopollenin wall?

Wind-blown spores are present and thick while swimming spores are absent.

What pigment evolved in streptophytes?

Chlorophyll b

Which pigment is in all photosynthetic organisms?

Chlorophyll a

Accessory photosynthetic pigments

Absorb light in different wavelengths than chlorophyll a (reaction center). Ex: chlorophyll b and carotenoids; can help increase photosynthetic efficiency

flavonoids protect from uv exposure

can serve as a private communication channel with pollinators

What are mycorrhizae?

Association with fungi that provide nutrients to plants

ectomycorrhizal fungi wrap themselves around the plant, increasing surface area for water and mineral absorption

vesicular arbuscular mycorrhizal fungi grow into root cells and exchange water and nutrients

Land plants have alternation of generations

Refers to the fact that there are both haploid and diploid multicellular stages. this life cycle is a synapomorphy for the land plant clade

spores grow via mitosis to produce haploid multicellular gametophytes, which make gametes in gametangia

two types of gametangia: antheridia and archegonia

antheridia - make sperm

archegonia - make eggs

eggs are fertilized to make diploid zygotes