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BIOL 227 - Plants & Algae > Test 2 > Flashcards

Test 2 Flashcards

1
Q

What does photosynthesis provide?

A
  1. Provides food - plants and animals
  2. Provides habitat
  3. Fossil fuel energy
  4. Regulation CO2 & global temperature
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2
Q

What is photosynthesis?

A

Converts light energy to chemical energy.

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3
Q

Photosynthesis Equation

A

CO2 (carbon dioxide) + 2H2A (electron donor) + Photons (light energy) –> [CH2O] (carbohydrates) + 2A (oxidised electron donor) + H2O (water)

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4
Q

Cancelled equation (water on both sides)

A

CO2 + H2O + light –> [CH2O] + 2O

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5
Q

LIGHT REACTION

A

Capture light energy to make NADPH + ATP.
Occur in Stomata

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6
Q

DARK REACTION or Calvin Cycle

A

Use NADPH and ATP to reduce CO2 to make sugar. Can occur in dark.

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7
Q

DARK Equation

A

6CO2 + 12NADPH + 12+ + 18ATP —> 1 glucose + 12NADP+ + 18ADP + 6H2O

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8
Q

Pigment

A

All photosynthetic organisms have chlorophyll a

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9
Q

RuBisCO

A

Used to carbozylase sugars, by transforming CO2.
In order to function, needs to be LOW oxygen conc. within chloroplast.

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10
Q

Light harvesting pigments

A

Phylocoid membrane, light entering chloroplast.
Light dependent phosphorylation + water.
O2 byproduct NOT food for dark reaction.

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11
Q

Thylakoid

A

Abosrbs light

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12
Q

Z scheme

A

Source is WATER.
1. Oxygen evolving splits H2O into O2 and H+.
2. Light hits PSII, P680 to P680* (can oxidise water)
3. Electrons travel, decrease energy, makes ATP. (3) is an enzyme that catalyses electron transfer. Electron transport chain.
4. Light hits PSI, P700 to P700*
5. Ferredoxin + Membrane bound sulfur protein, NADP+ and H+ undergo reductase to make NADPH+

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13
Q

What is the purpose of light reactions?

A

To create ATP and NADPH that are then used in the dark reaction

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14
Q

Photorespiration

A

Process of O2 reduction and scavenging of oxygenase.

Decrease in seawater with low O2.

Converts RuBisCO oxygenase into triose phosphate.
Costs lots of energy.

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15
Q

Forms of RuBisCO

A

i. Primary form, cyanobacteria
ii. Bacterial enzymes + dinoflagellates
iii. Archael form II
iv. No carboxyalse or oxygenase activity

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16
Q

PIGMENT: green plants / algae

A

Resembles abosrpition for chlorophyll and carotenoids with violet-blue and red light

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17
Q

PIGMENT: red algae

A

Action spectrum is blue-green.
Algae use blue to grow in deeper water

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18
Q

How can you measure photosynthetic rates?

A

Chambers

Measuring waste oxygen

O2 evolved vs. CO2 uptaken isn’t always equal.

Chlorophyll fluroescence

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19
Q

Chlorophyll fluroescence

A

Measures the movement of electrons and diffusion of light.

Measure when light hits PSII

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20
Q

Respiration

A

Takes up O2 and produces CO2
In plants creates ATP

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21
Q

What happens if it oxygenates rather than carboxylates?

A

Losing energt + Nitrogen

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22
Q

CCM

A

CO2 Concetrating Mechanism
Concentrate CO2 at site of RuBisCO

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23
Q

Limitations - water + CO2

A

Water can be limiting in terrestrial, but CO2 is abundant and diffuses rapidly

CO2 can be limiting in marine freshwater environment and diffuses slowly, water is more abundant.

24
Q

C3, C4, CAM (presence of CCM)

A

C3: non-CCM
C4: CCM
CAM: CCM

25
Q

C3 Plants

A

CO2 + H2O + RuBP —> (2) 3-phosphoglycerate

Catalysed by RuBisCO
C3 photosynthesis is non-CCM photosynthesis in terrestrial.

C3 lost 97% of water taken up by roots, leaves through stomata.

BETTER in low light and low temperature.

26
Q

Stomata

A

Cell structures on leaves that enable exchange of CO2 and H2O between plant and environment.

27
Q

Open / Closed Stomata

A

When open stomata can lose H2O. C3 plants close to prevent water loss.

When closed stomata prevent CO2 uptake.

If stomata is closed OXYGEN builds up, increases photorespiration in C3 plants.

28
Q

C4 Plants

A

More common in tropics, water loss is higher, but lots of light.
Arranged more isolated. Leaves TWO regions called mesophyll and bundle sheaths.

Uses PEPC to form 4 carbon sugar. Requires more ATP, but allows concentration of Co2 during high temperature. C4 have better water efficiency.

Enter calvin cycle in bundle sheath rather than mesophyll like C3 and CAM.

29
Q

CAM plants

A

Temporally segregate, instead of spatially. Stomata opens at night, Co2 reacts with PEP to form malate. Malate is stored until daytime, then carboxylated and CO2 released to follow C3 process.
SIMILAR to C3, except for temporally segregated.

30
Q

CMM in Algae

A

CCM concentrations are MUCH lower. Limiting in water compared to terrestrial.

CO2 still concentated at site of RuBisCO but requires:
1. Active energetic transport from water to RuBisCO
2. Mechanisms to trap CO2 and avoid leakage.

31
Q

How does HCO3- uptake occur?

A
  1. Energized direct uptake (true CCM)
  2. Catalyzed external conversion of HCO3- into CO2 to enhance diffusion (not true CCM)
32
Q

Catalysed difussion

A

Enzyme carbonynic anhydrase (CA) can externally catalyze the natural reaction of HCO3- to CO2 to enahnce diffusive uptake of CO2 (external anhydrase)

Internal CA needs to convert CO2 back to HCO3- for storage within the cell, to reduce leakage.

33
Q

Non-CCM strategy

A

not-true CCM as internal CO2 concentration at RuBisCO isn’t elevated.
Requires less energy than true CCM. Cannot photosynthesise when pH is higher than 9.

34
Q

Energised HCO3- uptake (CCM) taken up how?

A
  1. Antiport (take up one, spit out another)
  2. Symport
  3. Uniport
35
Q

What would happen if lots of HCO3- was taken up?

A

Need pH balance in the cell, if we take up -ve charge, we need to take up +ve charge. Have to spit something to make up pH equilibrium

36
Q

What would happen to CO2 during catalyzed diffusion?

A

Diffuse through membranes as the concentration becomes higher inside the cell compared to outside
Interior of the cell requires pH balance
ALL requires energy

37
Q

What is the difference between a C3 and C4 plant?

A

C3 are non-CCM, C4 are CCM.
Overcome the problem of water loss, through STOMATA opening + closing.
RuBisCO oxygenates instead of carboxylates

38
Q

What is the difference betwen a C4 and CAM plant?

A

C4 have two seperate cycles physically (mesophyll + bundle sheaths), CAM do temporally (night + day), Use enzyme, CCM function underwater.
Some algae can directly take up bicarbonate.

39
Q

Cost of CCM

A

Costs energy
Costs nitrogen
Some marine environments energy is scarce

40
Q

C3 (non-CCM)

A

Fixes 3 sugars, cannot operate under high temperature or dry conditions due to water loss or photorespiration

41
Q

C4 (CCM)

A

Spatial segregation (mesophyll, bundle sheaths), 4 C sugars made by PEPC transformed into carbon sugars

42
Q

CAM (CCM)

A

Temporal segregation of Carbon fixation (night + day), where malate is created at night by PEPC and stored until day, fixed by RuBisCO.

43
Q

C4 and CAM plants are more common as temperature increases

A
44
Q

Do C4 plants use less N than C3 plants?

A

YES
C4 plants also use less RuBisCO than C3 plants, use PEPC

45
Q

Shouldn’t C3 always be favored under higher CO2?

A

To do with Nitrogen levels. The Nitrogen is being drawn down in the blocks, C4 grass use less Nitrogne, benefiting overtime

46
Q

Terrestrial CCM favored in…

A

LOW water
HIGH temperature
LOW nitrogen

47
Q

Role of algal CCM in structuring communities

A

CCM requires high light energy
CCM requires high nutrients
CCM favored at low CO2 diffusivity
CCM use favored under lower CO2 concentration

48
Q

Nutrient uptake

A

The synthesis of most cellular components require more than just H, C and O
e.g., amino acids, ATP, nucleic acids

49
Q

Nutrient Uptake in Terrestrial plants

A

NITROGEN
Take up nitrate (NO3-)
Converted into nitrite (NO2-)
then ammonium (NH4+)
Then gluatmine
All uses ATP

50
Q

Uptake can occur via plant roots

A
51
Q

Sources of Nitrogen

A

Photochemical reaction (2%)
Lightning (8%)
Biological fixation (90%)

52
Q

Terrestrial plant: SULFUR

A

Structural proteins
Electron transport
Catalyze sites for enzymes
Secondary metabolites involved in growth and herbivore defense.

53
Q

Calcification

A

HCO3- + Ca2+ —> CaCO3 + H+
99% of organisms calcify internally

54
Q

Calcification process

A
  1. Bicarbonate and calcium pumped into cells
  2. Calcium carbonate minerals precipiate from a semi-fluid
  3. IN coralline algae this occurs within cell-wall
  4. In Halimeda this occures in specialised compartments
55
Q

Buoyant weight technique

A

BW is a way to excude water weight Avoids error in wet tissue

BIOL 227 - Plants & Algae (1 decks)

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