Marine environments

Question 1

Marine environment food type

Answer 1

Oligotrophic (nutrient poor)
Causes smallest cells to be found here

Question 2

Prolochlorphytes

Answer 2

They are M that populate the ocean
-4 ecotypes with each having 200 unique genes as well as utilising different wavelenghts of light and use different forms of nitrogen and Phosphorous (organic and inorganic)
-Related to cyanobacteria as they either contain chlorophyl A and B or A and D but they lack a specific pigment found in cyanobacteria
-they are olive green
-Produce organic matter that is dissolved in ocean

Question 3

Ecotype

Answer 3

Organisms of same species but have physiological differences

Question 4

Pelagic zone

Answer 4

open ocean and top layer

Question 5

M compensate for small size

Answer 5

They do this by producing many transport enzymes per unit volume to find nutrients in dilute environment such as dissolved organic matter (OM)

Question 6

Coastal zone nutrients

Answer 6

Has much more nutrients due to nearby terrestrial environment than pelagic zone which causes it to be anoxic (especially in benthic zone)

Question 7

Green algae

Answer 7

Eu that are phototrophs

Question 8

Open ocean compared to freshwater

Answer 8

-saline
-low in nutrients, especially N, P and Fe
-cooler (same temp whole year which prevents turnover from occuring)
-Because of size of ocean, microbial activities taking place in them are major factors in earth’s carbon balance

Question 9

OMZ

Answer 9

Oxygen Minimum zones
-regions of oxygen-depleted waters at intermediate depths
-High O2 demand
-Nutrient-rich areas
-High levels of denitrification and anammox
-OMZs are expanding

Question 10

Near-shore water ecosystems

Answer 10

Terrestrial runoff, retention of nutrients and upwelling of nutrient rich waters combine to support higher pops of phototrophic M than in pelagic waters

Question 11

Eutrophication and O2

Answer 11

Eutrophication resulting from nutrint inputs can lead to the waters becoming intermittently anoxic from the removal of O2 by respiration of heterotrophs and production of H2S by sulfate reducing B

Question 12

Oil spill effects

Answer 12

Deepwater Horizon oil spill was largest marine oil spill
-Oil released as a plume at great depths
-Bloom of hydrocarbon-degrading Gammaproteobacteria, Colwellia and Cytoclasticus
-Oil is source of carbon which causes anoxic environment
-Early growth of hydrocarbon-degrading B may have reduced environmental impact

Question 13

Prochlorophytes O2 production and size

Answer 13

-Most of the primary production in the open ocean is due to them
-Account for in pelagic zone:
>40% of marine phototroph biomass
~50% of net primary production

Question 14

M in tropical and subtropical oceans

Answer 14

Trichodesmium are planktonic filamentous cyanobacteria that are abundant phototrophs in these areas

Question 15

Coastal and marine M

Answer 15

Ostreococcus are small phototrophic Eu that are NB primary producers

Question 16

Aerobic anoxygenic phototrophs

Answer 16

-Carry out photosynthetic light reactions only under oxic conditions
-Class of marine microbes that use light energy but do not fix CO2 or produce O2
-Light is used for ATP synthesis via photophosphorylation
-They have filaments called rhodopsin to capture light
-Supplement heterotrophic diet with light

Question 17

Pop density and depth numbers

Answer 17

Surface waters contain 10^6 cells/ml that drop to 10^3-10^5 cells/ml below 1000m in depth

Question 18

Relationship of B with depth

Answer 18

B tend to dominate in surface waters and are near equal with Arcahe in deeper waters
-deeper waters have less light O2, dissolved carbon and other nutrients

Question 19

Why do Archae=B in deep waters

Answer 19

Archae can use waste products of anaerobic respiration more efficiently than B

Question 20

Oligotroph

Answer 20

An organism that grows best at very low nutrient concentrations

Question 21

Most abundant heterotroph

Answer 21

Pelagibacter

Question 22

Marine oligotroph mechanism

Answer 22

Pelagibacter and other marine heterotrophs contain proteorhodopsin, a form of rhodopsin that allows cells to use light energy to drive ATP synthesis

Question 23

Viral density

Answer 23

10^8 viral particles/ml

Question 24

B survive large amounts of viruses

Answer 24

B use defences such as restriction enzymes and CRISPR
-Very little actually infect, most are killed by host defences and UV light

Question 25

Virus diversity

Answer 25

Viruses affect prokaryotic populations and are highly diverse
-Bacteriophages and Archaeal viruses in seawater
-non-tailed dsDNA viruses appear to dominate in global ocean like Autolykiviridae

Question 26

Virus importance

Answer 26

-Introduce diversity into genomes
-Regulate population densisty of microbes

Question 27

Prochlorophytes ecotypes

Answer 27

They are most abundant marine oxygenic phototroph
-predator resistance
-Nitrogen availability
-temperature
-low-light adaptions

Question 28

Prochlorophytes ecotypes

Answer 28

They are most abundant marine oxygenic phototroph
-predator resistance
-Nitrogen availability
-temperature
-low-light adaptions