Introduction Marine Synthesis - part 1 - Gidon

Question 1

(Some of) the main players in Marine photosynthesisers

Answer 1

• Cyanobacteria
• Phyto / zooplankton – how do we study plankton in the sea ?
• Algal (Algae)
• Seagrasses
• Corals (photoinhibtion)

Question 2

How many percent Earth’s surface cover by OCEAN?

Answer 2

Approximately 71%

Question 3

How many percent Earth’s surface cover by WATER?

Answer 3

Approximately 72%

Question 4

What is Primary productivity?

Answer 4

The net amount of CO2 taken up over time

Question 5

How many percent of global PRIMARY PRODUCTION do by AQUATIC PLANTS?

Answer 5

> = 50% (photosynthesis) of Global

Question 6

How many Global primary production do by TERRESTRIAL?

Answer 6

Estimated at 60 Gt carbon/year

Question 7

How many Global primary production do by MARINE?

Answer 7

Estimated at 65 Gt carbon/year

>5 Gt compared w terrestrial

Question 8

What are these advantage of OCEAN compare w LAND?

Answer 8

• AREA

- VOLUME

Question 9

The elevation of the land surface of the Earth?

Answer 9

• 418 m (Dead Sea) to 8,848 m (Everest)

Question 10

AVERAGE height of land above sea level is?

Answer 10

840 m

Question 11

The deepest of the oceans??

Answer 11

-10,994 m (Mariana Trench)

Question 12

How many times An Ocean’s average depth bigger than AVERAGE height of land above sea level ?

Answer 12

4.5 times

Question 13

What is the process of PS?

Answer 13

CO2 + H2O C6H12O6 + O2

Question 14

What is the process of Chemosynthesis?

Answer 14

CO2 + H2O + H2S + O2 C6H12O6 + H2SO4

Question 15

What is The “primary producers” of Chemosynthesis process?

Answer 15

Chemosynthetic bacteria (use H2S)

Question 16

What is the photic zone?

Answer 16

Enough light for net photosynthesis (average 100 m depth)

Question 17

What are these PS producer in Photic zone?

Answer 17

• Cyanobacteria
• Macro algae
• Phytoplankton
• Coral reef
• Seagrass meadows

Question 18

What is Cyanobacteria?

Answer 18

Prokaryotic unicellular

or filamentous phytoplankton

Question 19

What is the Habitat of Cyanobacteria?

Answer 19

Everywhere (terrestrial and aquatic habitat),
( the most successful group of microorganisms on earth.)

Can be found in the most extreme niches: hot springs, salt works, and hypersaline bays.

Question 20

How many Cyanobacteria species?

Answer 20

1500 species (10% marine)

Question 21

Two main species?

Answer 21

Unicellular and colonial species

Question 22

What kind of form of Colonies (colonial species) ?

Answer 22

• Filaments (can be attached to sediment,
  seagrasses / macro algae (biofilms)
• Sheets
• Hollow balls

Question 23

What is the name of Unicellular cyanobacteria discovered in 1986?

Answer 23

• Prochlorococcus (1986)

Question 24

Name of 2 photosynthetic cyanobacteria - primary

producers in the ocean, responsible for at least 50% of atmospheric oxygen?

Answer 24

Prochlorococcus

and Synechococcus

Question 25

What is the habitat of filamentous cyanobacteria?

Answer 25

Found in nutrient poor tropical and subtropical ocean waters.
(can live in solitude or in colonies (form of colonies: blooms or can be extensive on surface waters ).

Question 26

More information about cyanobacteria (Trichodesmium)?

Answer 26

Cyanobacteria are Diazotrophes
(dia = two, azo = nitrogen, only prokaryots)
- Fixes atmospheric nitrogen into ammonia
- Biological nitrogen fixation: N2 + 8 H+ + 8 e− → 2 NH3 + H2

• This process requires a substantial amount of energy (in the form of ATP) in order to
  break the triple bond between the nitrogen atoms

Question 27

Why do we call Marine diazotrophs are Global biochemical cycle of N?

Answer 27

Because Marine diazotrophs fix 150,000,000-200,000,000 tons (0.15-0.20 Gt) atmospheric N2 yr-1

Question 28

Not all Cyanobacteria are unicellular but have filamentous cyanobacteria.
What is the name of one of them ?

Answer 28

Trichodesmium

Question 29

The Dilemma with cyanobacteria

Answer 29

The enzyme nitrogenase (enzyme fix N2) is extremely sensitive to oxygen - inactivated by oxygen - (thus requires a near‐to‐anoxic environment)
and Oxygen production during photosynthesis.

Question 30

Solution of The Dilemma with cyanobacteria

Answer 30

• Heterocysts (meaning: no photosynthesis), create a micro-anaerobic environment,
• Nitrogen fixation during the night
• Nitrogen fixation within dense flakes of filamentous cyanobacteria , the centre being oxygen depleted (no Oxi)

Question 31

What is the special of filamentous cyanobacteria (diazotrophes) - Trichodesmium

Answer 31

Iin tropical seas, responsible for fixing one quarter of the nitrogen in the world’s ocean.

Question 32

Fixing nitrogen – summary:

Answer 32

The enzyme complex responsible for the fixation of N2.
Is sensitive to oxygen and requires a near‐to‐anoxic environment.

Cyanobacteria are phototrophic organisms evolving oxygen and they
developed various strategies to combine this with N2 fixation.

In order to fix N2, cyanobacteria separate the incompatible processes of oxygenic photosynthesis and N2 fixation spatially (in different cells) or temporally (during the night), or a combination of both.

Question 33

Another function of Cyanobacteria: “Earth food”.

What is the name one of them?

Answer 33

Spirulina sp.
(Rich in protein, vitamins, minerals, and carotenoids,

Especially, antioxidants that can help protect cells from damage)

Question 34

The theory from Prokaryotes (cyanobacteria) to eukaryotes (microalgae)

Answer 34

Endosymbiotic theory:

evolutionary theory that explains the origin of eukaryotic cells from prokaryotes .

Question 35

The proof of The theory from Prokaryotes (cyanobacteria) to eukaryotes (microalgae) -
(Endosymbiotic theory)

Answer 35

The Mitochondrion (found in most eukaryotic cells) and the chloroplasts (found in all
eukaryotic algae) evolved from cyanobacterial ancestors via endosymbiosis

Question 36

2 types of Endosymbiotic theory:

Answer 36

• Primary endosymbiosis: Prkaryote + Eukaryote = Eukaryote
• Secondary endosymbiosis: eukaryote cell engulfs another eukaryote cell that has undergone primary endosymbiosis
  (Eukaryote + Eukaryote = Eukaryote)