Lecture 9- Ocean primary productivity Flashcards Preview

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Flashcards in Lecture 9- Ocean primary productivity Deck (31):

What is the function of photosynthesis?

-light energy is captured by chlorophylls and stored in chemical bonds of carbohydrates (e.g glucose) -6CO2+6H2O= C6H12O6+ 6O2


How much of primary productivity occurs in the oceans?



What is meant by primary productivity?

-taking inorganic material and changing them into organic (sunlight into energy)


What is respiration in relation to photosynthesis?

-the opposite reaction -C6H12O6+602=6CO2+6H2O -there must be more photosynthesis than respiration


What does chlorophyll in an environment indicate?

-photosynthesis -but not at night! they then respire


How does the distribution of chlorophyll change seasonally?

-it is more abundant in areas that are experiencing summer (mostly)

-dark blue= no chlorophyll

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What organism contribute to marine primary productivity?

-algae (green, brown and red) -plants (seagrasses) -phytoplankton(bacterial and eukaryotic)


What is the algal contribution to marine primary productivity?

-they are limited in their growth by depth -only up to 50m as they have to be attached to the sea floor -only in coastal areas, not a major contributor to marine primary productivity, more habitats though!


What is the plants' contribution to marine primary productivity?

-also only around coast -non-significant contributors


Who are the biggest contributors to primary marine productivity?

-phytoplankton as they are not limited by depth, can float


How large can phytoplankton blooms be?

-1000s of kilometers


What are the non-photosynthetic primary producers in the sea?

-chemoautotrophic bacteria by the volcano vents, not a major contributor to marine primary productivity


What are the characteristics of cyanobacteria? (type of cell, cell wall type and single celled?)

-part of phytoplankton -prokaryotes -gram negative cell walls -can be single celled, filamentous, or form thalli


In what ways can cyanobacteria be motile?

-can be motile (flagellar, gas vesicles=so they float, gliding) -gliding= freshwater


What colour are cyanobacteria and why?

-typically blue-green due to phycobiliproteins -aslo chlorophyll a


What element can cyanobacteria fix?

N2 -key nutrient for protein, these can take it out of the air and capture it so others can use it too


Is it true that cyanobacteria form toxins?

-some do -often freshwater that doesn't move very much


Give an example of a cyanobacteria?

-Prochlorococcus -one of the most important organisms in the oceans


Can cyanobacteria form colonies?


-common in tropical waters -colonies of aggregated filaments

-forms visible blooms

-in warmer waters

-can control their buoyancy and can float on the top

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What is the colour and structure of diatoms?

-golden brown due to accessory pigments (chlorophyll c) -surrounded by intricate structures made out of glass= their cell wall -second most important primary producers after cyanobacteria -build a frostule= glass house, pure glass -little holes= for gas exchange, as glass nonpermeable


What is the structure of the glass house of diatoms?

-glass houses made up of two valves, (like a petri dish, one smaller and fits into the other one)

-then divides and form new 2 valves on the inside (so four cells now)

-but there is quite lot of variation, some insert girdle bands=make it possible to grow longer

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What are the two major groups of diatoms?

1.Centric diatoms 2.Pennate diatoms


What are the characteristics of centric diatoms?

-radial symmetry -nonmotile= do not have flagellas

-planktonic(means they float around carried by the currents etc.)

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What are the characteristics of pennate diatoms?

-bilateral symmetry -motile(gliding system) -sessile on rocks and ice -only sperm cells have flagellas -non-planktonic

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What do centric diatoms have spines for?

-some centrics have long spines= helps them in the currents -the spines when divide hold cells together= colony


What is the structure and motility system of the pennate diatoms?

-pennates, have long slits that goes almost down to the middle -this slit secretes carbohydrate= this will help it stick to a surface, then motor molecules in the membrane and then pull the cell along -leave a little goo train, more an more on and then other organisms eat it biofoulling -they store some of the carbs they photosynthesise= lipids and chrysolaminarin sugar -important in arctic regions, not as important in coastal and warm oceans


Where do lot of pennate diatoms grow?

-grow beneath polar sea ice -estimated to contribute 20% of primary productivity of Southern Ocean


What is the lifecycle of diatoms?

-Form resting stages and spores to survive conditions unsuitable to growth 

- cytoplasm is dense with lipid droplets and poly-phosphate granules

- can be dormant for decades

-when the ice melts= they float= form resting spores, withstand until ice forms again

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What is the colour of haptophytes?

-golden brown due to accessory pigments (chlorophyll c)


What is the haptophytes' cell wall made of?

-calcium carbonate scales (coccoliths)


What is the way of getting energy for haptophytes?

-they are both heterotrophic and autotrophic (some)