Algae and Symbioses

Question 1

What is an algae

Answer 1

polyphyletic grouping of eukaryotic photosynthetic organisms

Question 2

What does polyphyletic mean

Answer 2

organisms that don’t share an immediate common ancestor

Question 3

How are algae divided into groups

Answer 3

based on the class of the endosymbiont and the type of endosymbiosis

Question 4

What is an endosymbiont

Answer 4

organism that is engulfed and is now the symbiont to the large organism
type of symbiont found within the host

Question 5

What are the 3 main endosymbionts within algae

Answer 5

• cyanobacteria
• green algae
• red algae

Question 6

What does the green algae group include

Answer 6

• modern day green algae
• red algae
• glaucophytes
  all descended from single primary endosymbiosis event –> monophyletic

Question 7

What is Viridiplantae

Answer 7

new taxon where green algae is included as plants

Question 8

What is archaeplastida

Answer 8

new taxon to include all primary endosymbiont algae including terrestrial plants, modern day green algae, red algae, glaucophytes

Question 9

What are the characteristics of modern day green algae

Answer 9

• all species of green algae
• diverse group
• all species look the same
• green bc chloroplast contain chlorophyll a & b

Question 10

What are the characteristics of red algae

Answer 10

• mostly multicellular
• form large clumps
• 95% marine, 5% freshwater
• simplified chloroplast with the phycobiliprotein pigment –> responsible for red colour

Question 11

What are the characteristics of glaucophytes

Answer 11

• unicellular & freshwater species
• mix traits of red and green algae
• contain chlorophyll a & b and phycobiliprotein
• chloroplast retains the peptidoglycan layer of cyanobacteria

Question 12

What are the characteristics of blue-green algae

Answer 12

• not algae but cyanobacteria
• fed by excessive nutrient flow into aquatic systems
• toxic

Question 13

What is a lifecyle

Answer 13

steps involved in the life and reproduction of a species

Question 14

What is the lifecycle in plants

Answer 14

• both haploid and diploid life stages grow into a multicellular organism. they both release haploid forms

Question 15

What is an alternation of generations

Answer 15

each generation is different from the preceding generation even though they are the same species

Question 16

What are the two different generations

Answer 16

• sporophyte generation = diploid produces haploid spores through meiosis
• gametophyte generation = haploid produces haploid gametes through mitosis

Question 17

What is the algae lifecycle

Answer 17

• most green and red algae have alternation of generations
• glaucophytes reproduce sexually –> no sperm
• require water for reproduction
• red algae has immobile sperm
• green algae has both motile and immobile sperm

Question 18

What is the advantage to asexual lifecycle

Answer 18

in stressful conditions –> use sporophyte generation because of fast reproduction

Question 19

What is the advantage to a sexual lifecycle

Answer 19

in normal conditions –> use gametophyte to increase genetic variation –> healthier population

Question 20

Green algae is a key partner in symbioses in which two organismal groups

Answer 20

Lichens & sea sponges

Question 21

What are the characteristics of lichens

Answer 21

• complex of a fungal species
• partner = green algae and cyanobacterium
• highly successful group
• can reproduce asexually
• organism containing mycobiont and photobiont

Question 22

What is a mycobiont

Answer 22

fungal partner that provides protection from desiccation

- controls the rate of division for photobiont

Question 23

What is a photobiont

Answer 23

photosynthesizer that provides carbohydrates to mycobiont through photosynthesis

Question 24

What are the characteristics of sea sponges

Answer 24

• basal group of animals
• freshwater species
• only some form symbiosis mostly with cyanobacteria
• minority of sea sponges has green algae as an endosymbiont