Green Algae

Question 1

Viridiplantae (green plants) are split into two discrete lineages

Answer 1

1. Chlorophyte green algae
2. Streptophytes (charophyte)
3. Embryophytes (land plants)

Question 2

What evolutionary event initiated the green lineage?

Answer 2

endosymbiosis of a cyanobacteria

Question 3

What traits distinguish all green algae and land plants from all other eukaryotes?

Answer 3

1. Primary green plastids
   
   • 2 membranes
   • Chl a / Chl b
2. Carbohydrates stored as ‘true’ starch
   inside plastids
3. Stellate structure of the transition zone
   between the flagellum & the basal body

Question 4

What are Stellates?

Answer 4

1. Stellates structure links 9 pairs of
   microtubules in the flagellar base
2. In the transition zone between the basal
   body and the flagellar axoneme

Question 5

Non-molecular traits that differ between two green algal lineages: Chlorophytes green algae

Answer 5

1. Apical flagella
2. 4 flagellar roots in a symmetrical cross-
   shaped arrangement
3. Cytokinesis via furrowing and/or
   phycoplast in derived lineages
4. Non-rosette cellulose synthase

Question 6

Non-molecular traits that differ between two green algal lineages: Charophytes & land plants

Answer 6

1. subapical or lateral flagella - but many
   w/o flagella
2. Asymmetrical flagellar roots w/
   multilayered structures & parallel basal
   bodies in most
3. Cytokinesis via cell plate & pharmoplast
   in all but basal groups
4. Rosette configuration of cellulose
   synthase in most
5. Several unique enzymes or enzyme
   systems

Question 7

How are Chlorophyte algae so diverse in morphology & ecology

Answer 7

1. unicellular, biflagellates &  
    quadriflagellates
2. unicells without flagella
3. Colonials (few-celled to 1000 of cells)
    - motile
    - non-motile
4. Filamentous: cells dividing in one plane
    - unbranched 
    - branched
5. Pseudoparenchymatous
6. Siphonous
7. Membrane sheets
8. Parenchymatous: cells divide in three  
    planes

Question 8

Chlorophyta: Habitats?

Answer 8

Most abundant and diverse in freshwater environments

Question 9

Some chlorophytes are calcareous due to…..

Answer 9

Deposition of CaCO3 in their outer cell walls

Question 10

Chlamydomonas

Answer 10

1. Motile unicellular chlorophytes
2. Basal clades of chlorophyte green algae
   are unicellular biflagellates
3. Important model system

Question 11

Non-motile, unicellular chlorophytes morphology/habitats

Answer 11

1. morphology: Coccoid

2. Habitats: Soil, benthos, endosymbionts

Question 12

Motile Chlorophyte Colonials

Answer 12

Volvox

Question 13

Non-motile Chlorophyte Colonials

Answer 13

Hydrodictyon

Question 14

Filamentous Chlorophytes

Answer 14

1. Cell division in one plane

2. Oedogonium

Question 15

Pseudoparenchymatous Chlorophytes

Answer 15

1. Anadyomene stellata

2. Codium fragile

Question 16

Siphonous Chlorophytes

Answer 16

1. Coenocytic: one large cell with many
   nuclei
   
   • these algae undergo repeated mitotic
     division without cell wall formation
2. Tubular Construction
   
   • green word for tube is siphon
3. Sometimes tissue differentiation
   
   • holdfast, stipe, leaf-like structures

Question 17

Ventricaria (Valonia)

Answer 17

1. Sailor’s-eyeball, sea pearl, bubble algae
2. common in tropical marine waters
3. the world’s largest ‘cell’ by volume

Question 18

Acetabularia

Answer 18

1. Mermaid’s wine glass

2. unicellular but has just one nucelus for most of its life cycle

Question 19

Membranous green algae

Answer 19

1. Ulva (sea lettuce)
2. Cells divide in two places to form a 1-
   layered sheet, then divide again in 3rd
   plane so sheet becomes 2 cell-layers thick
3. Holdfast
4. Membranous sheath
5. Qingdao Bay Incident

Question 20

Parenchymatous Chlorophyte

Answer 20

1. Fritschella
2. Prostrate system near the soil surface is
   parenchymatous
3. Upright branches are filaments
4. Adaptation to terrestrail life