Lecture 9 Plants 1: Marine algae & photosynthesis

Question 1

Sister groups are

Answer 1

two groups split from common node

Question 2

Which eukaryotes photosynthesize (7)

Answer 2

Archaeplastids, Amoebozoans, Hapitista, Stramenopiles,
Alveolates, Rhizarians, Discobids.

Question 3

Photosynthesis is (3)

Answer 3

process that converts light energy to chemical ~. Fix carbon to organic form, produces oxygen.

Question 4

Are all photosynthesizers plants

Answer 4

Not all photosynthesizers are plants and vice versa (parasitic “ghost pipe” can’t photosynthesize)

Question 5

History of origin of photosynthesis (3 stages)

Answer 5

First oxygenic photosynthesis 2.5-3 bya
Developed multicellularity & cell specialization 2.2-2.5 bya
Great Oxidation Event appeared in Earth’s atmosphere (caused 1st mass extinction, possibility of complex life).

Question 6

Clues of how eukaryotes got photosynthesis: (2)

Answer 6

Both photosystems (PSI/PSII) evolved in bacteria.
All photosyn. euka. use chloroplasts.

Question 7

Chloroplasts are

Answer 7

Membrane-bound organelle, site of photosynthesis

Question 8

Describe capture of photosynthesis and evidence (3)

Answer 8

Endosymbiosis of chloroplasts. Mitochondria came before chloroplasts.
Evidence:
Chloroplasts similar to cyanobacteria & behave independently:
Replicate by fission, independent of cell division
Make some of their own proteins. Have circular DNA. Peptidoglycan in cell wall.
Chloroplasts have at least a double membrane.
Recent endosymbiotic cyanobacteria in cells of euka & animals

Question 9

How many membranes for photosynthesizer other than plants (2)

Answer 9

These other groups could have endosymbiosis with common ancestor of Plantae so more than 2 membranes.
Secondary endosymbiosis: red/green algal chloroplasts were transferred to other euka.

Question 10

Describe phytoplankton (5)

Answer 10

Single-celled, photosynthetic. 50% of global photosyn. Base of ocean food web. Free-floating

Question 11

2 types of phytoplankton and 2 types of multicellular photosynthesizers

Answer 11

Blue-green algae: cyanobacteria. Half the oceans primary productivity
Protists: dinoflagellates & diatoms (‘algae in glass houses”)
Brown algae (phaeophytes): multicellular. Brownish from carotenoid.
Red algae: most diverse marine seaweeds. Uni/multicellular.

Question 12

Describe brown algae’s carotenoid uses (3), structure (2), reproduction, and one example

Answer 12

Carotenoid: (photosyn., UV protect, Coloration)
Individual=thallus (no complex vascular system).
Chloroplasts with 4 membranes.
Reproduction: sexual & asexual. 1n and 2n.

Kelp: largest biogenic marine habitat, contain biodiverse invertebrates.
Keystone species in trophic cascades

Question 13

Describe red algae’s reproduction, living condition, color, coralline red algae and its uses (4)

Answer 13

Reproduction: sexual/asexual.
Can live at great depths.
Color from carotenoid.
Coralline red algae: calcareous deposits in cell walls
Help build coral reefs, attract coral larvae, patch up broken coral, reinforce skeleton
Slow-growing (vulnerable)

Question 14

Algae use for human (7)

Answer 14

food, thickener (soups, toothpaste, ice cream), agar, gelatin sub., packaging, sustainable fertilizer? biofuels?