FROM ALGAE TO TERRESTRIAL PLANTS

ALGAE

Kingdom Protista (some argue Kingdom Plantae)

Photosynthetic

Unicellular or Multicellular

- Unicellular = Diatoms, Dinoflagellates, Euglenoids

- Multicellular = Seaweed (Brown, Red or Green)

Plants evolved from Algae (linked by green algae)

BROWN ALGAE

PHYLUM PHAEOPHYTA

- Largest and most complex protists

- No true leaves or roots

- Contain specialized tissues

- Holdfast: structure anchoring algae to rock or other hard structure

- Stipe: stem-like structure

- Blades: leaf-like structure

BROWN ALGAE

PHYLUM PHAEOPHYTA

- Ex: Kelp, rockweed

RED ALGAE

PHYLUM RHODOPHYTA

- Appear to be the first multicellular organisms on earth (1.5-1.2 billion years ago)

- Most abundant large algae in warm tropical oceans

- Contain pigment chlorophyll (green)

- Contain pigment phycoerythrin (red)

- Allows red algae to thrive in large depths

RED ALGAE

PHYLUM RHODOPHYTA

- Ex: Nori (used to wrap sushi)

- Ex: Carrageenan (help ingredients mix)

GREEN ALGAE

PHYLUM CHLOROPHYTA

- Found in water, attached to tree surfaces and fur of sloths

- Structurally diverse

- Contain pigment chlorophyll

- Cell walls contain cellulose

- Store food in the form of starch

*** Most plant-like protist ***

GREEN ALGAE

PHYLUM CHLOROPHYTA

- Ex: Chlamydomonas (unicellular, flagella)

- Ex: Volvox (unicellular, flagella, ball-shaped colonies)

- Ex: Ulva/Sea Lettuce (2 cells thick, 1 m long)

THE SHIFT TO LAND

SIMILARITIES BETWEEN GREEN ALGAE AND PLANTS

** Refer to Page 93 for a phylogenetic tree depicting evolution

CHLOROPHYLL a and b

CELL WALL Made of cellulose

FOOD STORAGE Starch

DNA Similar sequences

ADAPTATIONS TO LIFE ON LAND

What adaptations are required for the movement from water to land?

- Protection from dessication

- Transport system for water and dissolved substances

- Support for body of plant

- Reproduction is difficult

Question: How did these adaptations evolve?

ADAPTATIONS TO LIFE ON LAND

Question: How did these adaptations evolve?

Answer:

Plants started small and grew in moist places

Water and dissolved substances transferred via osmosis and diffusion

ADAPTATIONS TO LIFE ON LAND

DIFFERENCES BETWEEN GREEN ALGAE AND PLANTS

GREEN ALGAE PLANTS

ENVIRONMENT Aquatic Terrestrial

REPRODUCTION Sporic Reproduction

Sporic ReproductionEmbryos

VASCULAR TISSUE

Not required Xylem and Phloem

SEEDS No seeds Seeds

FLOWERS No flowers Flowers

VASCULAR TISSUEXYLEM

- Carries water and minerals

- Dead, tube-shaped cells

- Contain lignin (very tough)

PHLOEM

- Carries larger molecules, including sugar

- Live, tube-shaped cells

ROOTS

- Strong anchor

- Absorb and transport water and minerals

VASCULAR TISSUE

SPORIC REPRODUCTION

Alternation of Generations

- 2 Multicellular stages

a) Gametophyte: produces haploid gametes by mitosis

b) Sporophyte: diploid version formed by fusing of gametes

- Produces spores by meiosis which develop into gametophyte

SPORIC REPRODUCTION