Lecture 12 - Algae & the Move to Land Flashcards
characteristics of algae
- > all photosynthetic eukaryotes except land plants
- > around 50% of the primary productivity of the earth (rate at which plants and other photosynthetic organisms produce organic compounds in an ecosystem)
What makes up Archaeplastida and describe their lineage
Red Algae: monophyletic lineage
Green algae: polyphyletic
- > chlorophytes and charophytes
Land Plants (some secondarily aquatic): monophyletic
What is cyanobacteria
blue green algae
What defines algae?
They are…
- > aquatic
- > eukaryotes
- > uni or multicellular
- > lack differentiation into shoots ands roots
Land plants evolved from what organism
they evolved from green algae
- > charophytes are the clostest relative to plants
What are three distinctive traits that ONLY charophytes share with land plants
- Rings of cellulose-synthesizing proteins
- Structure of flagellated sperm
- Phragmoplast formation
- > microtubules organize production of cell plate in dividing cell
What are the challenges to living on land
- > gravity
- > desiccation (staying moist)
- > dispersal
- > CO2 abundant but waxy surfaces impede absorption
- > light abundant but competition
Solutions to the challenges of living on land
Gravity
- > lignin for support/structure
Dessication
- > waxy surfaces, cells to protect gametes and spores
Dispersal
- > adaptation for gametes and spores
CO2 abundant but waxy surfaces impede absorption
- > pores for gas exchange
Light abundant but competition
- > height
- > vascular tissue moves stuff around
List the derived traits of land plants
- > alteration of generations
- > multicellular dependent embryos
- > apical meristems
- > multicellular gametangia
Explain alternation of generations of land plants
- > dominated by gametophyte in non vascular plants
Explain multicellular dependent embryos of land plants
- > multicellular diploid zygote retained and nourished by female gametophyte
- > walled spores produced in sporangia
Apical meristem
the growth region in plants found within the root tips and the tips of the new shoots and leaves
plant gametangia
Antheridia: sperm
Archegonia: egg surrounded by protective cells
- > fertilization takes place within archegonium
Origin of seedless vascular plants
- > they were the first plants to grow tall
vascular tissue = xylem and phloem
Explain the function of xylem and phloem in seedless vascular plants
Xylem: Tracheids(tube-shaped cells)
- > conducts water and minerals up from root
Phloem: cells arranged into tubes
- > move organic products throughout plant
- > plants can get taller
function of roots in seedless vascular plants
Roots: lignified so they can penetrate soil
- > the absorb nutrients and water
- > they anchor plants
- > act as storage
Functions of leaves and sporophylls in seedless vascular plants
Leaves
- > surface area for photosynthesis and CO2 capture
Sporophylls: modified leaves on which sporangia are produced
- > produce sporangia
What is the significance of seedless vascular plants
- > they dramatically change the atmospheric composition (reduce CO2)
- > contributes to global cooling/glaciations
- > thus, influenced the environments for other species and impacted their evolution
What is the difference between algae and an aquatic plant
- Different evolutionary lineages
- > aquatic plants are “land plants” - Morphology/Anatomy
- > Algae are non vascular and lack true roots, while aquatic plants have specialized tissue development and roots
