Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
26 Cards in this Set
- Front
- Back
Nutrients needed. |
Nitrogen, phosphorus, silicon, iron, vitamins, light. |
|
Phosphorus |
Used for structure; phospholipids in membrane; linkers in DNA. |
|
Sources of phosphorus |
Inorganic P - as limiting as N in freshwater; when dissolved, usually 0-2 um Organic P - degraded to phosphate by extracellular phosphatase - Alkaline in marine spp. - Acidic in freshwater spp. |
|
Is nitrogen accumulated as DIN or DON? |
DON, except in low concentrations within in vacuoles, most are organics (amino acids, nucleic acids, proteins) |
|
How is P accumulated? |
Polyphosphate (inorganic P) in high concentrations. |
|
How much P is needed in relation to N? |
1/10 |
|
Which is more limiting, N or P? |
P |
|
Define 'quota' |
The amount of material per unit of cell or carbon |
|
What is growth rate related to? |
Quota of limiting nutrients; N, P and vitamins |
|
How can quota behave? |
- Range from Qmax to Qmin - Exceed Qmax up to Qabs, but them not affect K (therefore is not limiting) |
|
P is highly concentrated, involved in energetics, therefore... |
Rapid recycling can compensate for low P concentration. |
|
What do the quota curves for P and N look like? |
P has a steep start and plateau, it reaches Qmax quickly, whereas N has a more shallow curve. |
|
Is growth a function of internal or external nutrients? |
Internal. If there is an absence of external nutrients, growth continues until Q = Qmin |
|
What is KQ? |
Growth rate quota |
|
What does KQ describe? |
The curve shape, irrespective of the range of Qmin, Qmax and Qabs. |
|
What is silicon (Si) used for in diatoms? |
- Frustules - Cell division |
|
Previously assimilated Si can't be redistributed within the cells, therefore... |
Quota relationship does not apply. |
|
What happens under non-Si limitation? |
Cell cycle is prolonged, more Si is deposited, therefore Si:C increases. |
|
What is silicate used for in diatoms? |
Cell walls - Rigid - Overlapping valves - These move apart during growth - New valves made inside existing ones |
|
How and where do diatoms have an advantage? |
In high nutrient, upwelling waters; kept from sinking; Si supply. |
|
What [compound] is [Si] similar to? |
NO3- |
|
What happens during the G1 phase? |
Cell expansion |
|
What happens during the G2 phase? |
Cells prepare for division |
|
What happens during the M phase? |
Mitosis and cell division |
|
What happens in Si limited cells? |
Less Si per cell - Spines (SSi) disappear - Girdle (GSi) gets larger but cell cannot divide |
|
What happens in N limited cells? |
- More spines - Retain more Si per cell |