Biol 120: Plant Biology
Lecture 3 Summary
• homology: a structural likeness between corresponding parts
of different organisms.
• Autotrophs: “self-feeder”; An organisms that can make its
own food through photosynthesis.
• Heterotroph: “other feeder”; An organism that obtains food
from other organisms.
• Mixotroph: an organism that has both autotrophic and
• Endosymbiosis played a key role in the evolution of Algae
• Single celled organism
• Most live in freshwater
• they have two flagella
• some are NON-photosynthetic
o the photosynthetic variety contain Chlorophyll a & b,
o have a pyrenoid: protein-rich structure containing
o have an “eye spot” and light detector to avoid the
o some species are mixotrophs.
o reproduce asexually
o carbohydrate is stored as glucose polymer “paramylon
Phylum Chromophyta – Yellow/Green Algae:
• mostly freshwater
• most unicellular, some multicellular/colonial
• most have 2 flagella
• chlorophyll a & c, carotenoids
• Chloroplasts move in response to light intensity in
• reproduce mostly asexually – fragmentation or spores
• ie: Vaucheria, has endosymbiotic relationship with a sea slug. Biol 120: Plant Biology
Division Haptophyta - Phylum Prymnesiophyta:
• contain chlorophyll a & c, and carotenoids
• majority are marine
• account for 50% of photosynthesis in mid-Altlantic
• have 2 disc-shaped chloroplasts
• have 2 flagella
• live in gelatinous colonies
• Phaseocystis produces UV absorbing compounds and releases
Brown Algae (Kelp) – Phylum Phaeophyta
• chlorophyll a & c, carotenoids (fucoxanthin)
• mostly in shallow marine environments
• produce spores and gametes
• sessile, have heteromorphic generations, good habitats for
other animals, source of algin (paint, cosmetic products).
Red Algae (Seaweeds) – Phylum Rhodophyta
• chlorophyll a & d, and Phycobiliproteins
• mostly marine
• no flagellated life cycles
• complex life cycles, use for production of nori, agar and
Green Algae – Phylum Chlorophyta
• share common ancestor with plants.
• most freshwater, some terrestrial
• chlorophylls a & b, and carotenoids.
• store starch inside plastids
• Class Charophyceae
o Unicellular, colonial, and multicellular.
o genus Coleochaetales and Charales are closest relatives
of plants among algae.
Charales (stoneworts) form mineralized cell walls.
o has many similarities to plants: apical growth,
phragmoplasts and cell plates during mitosis, lignin-like
compound, reproductive cells are protected.
• ie, Chlamydomonas, Volvox, Chara
Changes in Environment Biol 120: Plant Biology
• 450-700mybp, ~2% O2 in atmosphere
• fossils of land plants appear ~450mybp
o liverwort fragments
• water was essential for growth and reproduction
• plants were mostly limited to moist environments
• they were small as they were fighting gravity
• A division of small, simple plants that comprises the mosses
• Are NO