Rhodophyta

Question 1

Majority of seaweeds are what type of algae

Answer 1

Red- more diverse than all other seaweed groups combined

Question 2

Where is red/ brown algae dominate

Where is green algae dominant

Answer 2

Tropical and temperate

Polar and sun polar

Question 3

__________ algae are one of the oldest groups of eukaryotic algae

Answer 3

Red

Question 4

Chloroplasts of red algae appear to have originated from ________ by ______ endosymbiosis

Answer 4

Cyanobacteria

Primary

Question 5

The major feature of a red algal cell are a chloroplast with _________ per band and only _____ chloroplast membranes

Answer 5

One thylakoid
2

Question 6

What phylum have Floridean starch grains in cytoplasm

Answer 6

Red algae

Rhodophyta

Question 7

Floridian starch grains

Answer 7

Long term storage product

Similar to amylopectin of higher plants, is highly branched and resembles Cyanobacteria starch

(No amylose like green algae)

Question 8

Starch grains cluster around ________ of chloroplast in primitive red algae

Answer 8

Pyrenoid body

Question 9

Thylakoid structures in Rhodophyta

Answer 9

Unstacked (simile to Cyanobacteria)

Phycobilisomes occur on the surface of the thylakoids

Chlorophyll a found in the chloroplasts and carotenoids: zeaxanthin

Accessory pigments: phycoerythrin: absorption in green and reflect red

Question 10

Chromatic variation

Answer 10

Colour of red algae varies depending on where it grows
-orange/red light (long wavelength)->phycocyanins
-green light (short wavelength)->phycoerythrin

Species may be yellow-green when growing in the intertidal zone or deep purple when growing 10-20m below the surface (Subtidal zone)

Ratio of phycoerythrin to chlorophyll is much greater at low light intensisties

Question 11

Sulfated polysaccharides

Answer 11

Typical for many red algae
-major constituents of agar (less sulfated) and carrageenans (more sulfated)-> extracted for commercial uses

Question 12

Agar

Answer 12

Mainly obtained commercially from species Gelidium, pterocladia
-collected by diving, dragging and raking at low tide
-agar extracted under pressure in autoclave, decolonized and deodorized with activated charcoal, filtered-> food and drug

Question 13

Calcification of Rhodophyta

Answer 13

-Coralline red algae=heavily calcified walls
-helps establish fossil record
-crystalline calcite (forms of CaCO3)
-possible that CaCO3 formation helps hard best nutrients

Question 14

Red algae were probably the first __________

Why?

Answer 14

Multicellular organisms

-conspired of cellulosic microfibril network+amorphous matrix of sulphated polysaccharide polymers and mucigel

-sulfated polysaccharide polymers create a multicellular organism by hankering every cell in a gel mass
-mucigels expand with hydration and help cell dispersal and attachment

Question 15

Diffuse

Answer 15

Cell division is not localized

Early in multicellular red algae

Question 16

In most red algae, there is a meristematic region and growth via division of an _______

Answer 16

Apical region

Cell divisions of apical cells increase number of cells in filaments

Question 17

Septum and pit plugs in red algae

Answer 17

In most red algae, septum (cross wall) formation is incomplete leaving a membrane lined pore.

Put plugs used to fill opening in the cell wall

Form during cell division between sister cells (primary put plugs) and in some red algae, between adjacent cells (secondary pit plugs)

Variation in pit structure used to determine phylogenetic relationships

Hypothesized to increase stability of the thallus (no function in translocation) - currents moving them around so need strength

Question 18

Formation of pit plugs steps

Answer 18

1. Cross wall begins to form following cell division
2. Cell wall development stops before completely closing the opening between two cells
   3.parallel vesicles line up in the gap to form a “plug” (granular protein mass)
   4.Plug stabilized on either side by a flattened “plug cap” (carbohydrate dome)

Question 19

Formation of secondary out plug

Answer 19

1. Unequal cell division produces a smaller conjunctor cell
   2.Fusion of cytoplasmic between smaller and adjacent, non-sister cell
2. Nuclear transfer between cells (cell rendered binucleate)

Secondary pit plug connections help exchange genetic information between adjacent cells and strength the entire thallus

Question 20

Red algae sexual reproduction

Answer 20

Asexually by discharging unicellular, non motile spermatia into the water

Question 21

Sexual reproduction in red algae involved what?

Answer 21

-3 generations (triphasic): gametophyte, carposporophyte and tetrasporophyte

Question 22

Porphyra sp. attaches itself to rocks how?

Answer 22

Multicellular rhizoidal attachment (holdfast)

Question 23

Porphyra sp. thallus appearance

Answer 23

Begin life as uniseriate filaments but this stage is replaced by parenchymatous sheets of cells (1 to 2 cells thick)

Question 24

Porphyra sp. economic use

Answer 24

Nori

Question 25

Porphyra asexual and sexual reproduction

Answer 25

Asexual: neutral spores Sexual: blade stage (macro thallus= gametophyte); branched-filamentous stage (conchocelis stage=sporophyte)

Question 26

Cultivation of Porphyra sp.

Answer 26

Spores collected and seeded on shells After collecting of conchospores, these are now ready to be seeded and grown on cultivation nets in the field.