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Biology 3/4 > AOS2 > Flashcards

AOS2 Flashcards

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1
Q

Photosynthesis

A

Process of capturing light energy to power the production of glucose as energy.

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2
Q

Photosynthesis Inputs

A

6CO2 + 12H2O + (sunlight)

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3
Q

Photosynthesis Outputs

A

C6H12O6 + 6O2 + 6H2O

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4
Q

Stages of photosynthesis

A

Light-Dependent
Light-Independent

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5
Q

Light-Dependent

A

The first stage of Photosynthesis.
Occurs in the thylakoid membranes

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6
Q

Light-dependent inputs

A
  • 12 H2O
  • 12NADP+
  • 18ADP + Pi
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7
Q

Light-dependent outputs

A
  • 6 O2
  • 12NADPH
  • 18ATP
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8
Q

Light-dependent stages

A
  1. Light energy energises chlorophyll which pumps H+ and splits water.
  2. Oxygen is released from the chloroplast via stromata.
  3. H+ ions generate NADPH and ATP
  4. ATP and NADPH coenzymes then move onto the light-independent.
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9
Q

Light Independent

A

2nd stage of photosynthesis.
Occurs in the Stroma
NO LIGHT IS REQUIRED; reactions are energised by ATP and NADPH in coenzymes.

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10
Q

Enzymes in Photosynthesis

A

Catalyse reactions.
ATP synthase catalyses the reaction ADP + Pi = ATP.
Enzymes regulate each step ensuring reactions are sped up and controlled.

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11
Q

Coenzymes

A

Assists with reactions by donating energy.
Include: NADPH + ATP. (loaded)
Form unloaded NADP+ and ADP + Pi

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12
Q

Light-Independent Inputs

A
  • 6 CO2
  • 12 NADPH
  • 18 ATP
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13
Q

Light-Independent Outputs

A
  • Glucose
  • 6 H2O
  • 12 NADP+
  • 18 ADP + Pi
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14
Q

Light-independent steps

A
  1. CO2 enters the Calvin cycle and undergoes an initial reaction.
  2. NADPH donates hydrogen ions + electrons; ATP breaks into ADP + Pi to release energy
  3. CO2 molecules change and rearrange.
  4. Leftover O2 combine with Hydrogen ions from NADPH to form water.
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15
Q

Rubisco

A

The key enzyme of the light-independent stage.
- Binds to CO2 and facilitates further reactions in photosynthesis.
- Binds to O2 to initiate photorespiration.

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16
Q

Role of rubisco in photosynthesis

A

Calvin Cycle
Responsible for the initial changes to CO2.

High O2, Low CO2 = More photoresp.
Low O2, High CO2 = Less photoresp.

Produce Glucose; 6G3P; 1G3P leaves to make glucose.

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17
Q

Steps of the Calvin Cycle

A
  1. Carbon Fixation.
  2. Reduction.
  3. Regeneration.
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18
Q

Carbon Fixation

A

Conversion of CO2 and RuBP into 3-PGA.
- Carbon from inorganic CO2 is fixed into an organic compound (glucose).
- Rubisco takes carbon from inorganic gaseous form (CO2) and incorporates it into an organic compound (3-PGA).

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19
Q

Reduction

A

NADH donates electrons to an intermediate 3-carbon molecule in the cycle to produce G3P.

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20
Q

Regeneration

A

The RuBP molecules needed to start the cycle again are reproduced.

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21
Q

Problem with Rubisco

A
  • Sometimes O2 is used as a substrate instead of CO2.
    Without RuBisCO CO2 pairing, PHS cannot proceed.
    RuBisCO binds to O2 = Photorespiration.
    Less PHS = less glucose + wasted energy. This negatively impacts plants’ ability to grow, survive and reproduce.
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22
Q

Factors influencing RuBisCO

A

Substrate concentration
Temperature

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23
Q

Substrate concentration (RuBisCO)

A

More substrate = greater chance of binding to an enzyme + undergoing reaction.

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24
Q

When plants need to conserve water…

A

Stomata will close causing O2 produced to build up inside cells = increased photorespiration.

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25
Q

Temperature (RuBisCO)

A

Reg temp = RuBisCO affinity for CO2 is greater than O2.
High Temp = Affinity (attraction) for O2 is higher, leading to RuBisCO binding to oxygen more often, leading to photorespiration.

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26
Q

C3 Plants

A

No Features to fight photorespiration.
“Normal”
Normal photosynthesis.
No evolved adaptations to minimise photorespiration.
eg. Trees, Cereals, nuts, fruit and vegetables.

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27
Q

C4 Plants

A

Minimise photoresp by separating initial carbon fixation and the remainder of the Calvin cycle over space.
Light Dependent is different for C4 than C3.
Initial carbon fixation occurs in the mesophyll.
Remainder Calvin cycle in specialised cells (bundle sheath cells).

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28
Q

C4 Process (light-independent)

A
  1. CO2 enters mesophyll cells and fixed by PEP, creating oxaloacetate. (4-carbon cell)
  2. Oxaloacetate converts into malate (4-carbon molecule) capable of being transported to bundle-sheath cells.
  3. Malate breaks down, CO2 is released and enters the Calvin cycle –> glucose production.
  4. Pyruvate formed (from malate) is transported back to mesophyll cell and converted into PEP (ATP helps).
  5. PEP –> fixation of CO2 and production of oxaloacetate; cycle repeats.

ALWAYS HIGHER CO2 –> PHOTORESP MINIMISED.

29
Q

CAM plants

A

Minimise photoresp by separating initial carbon fixation and the remainder of the Calvin Cycle over time.
HOT ENVIRONMENTS.
Eg. Cactai, Pineapples, Vanilla.

30
Q

At night in CAM plants

A

Stomata open; to bring in CO2.
Malate formed from PEP –> (oxaloacetate) (same in c4 plants)
BUT…
Malate is then stored inside the vacuoles within mesophyll cells until day time.

31
Q

Daytime in CAM plants

A

Stomata remain closed, preventing water loss.
- Still PHS during the day; malate is cut out of the vacuole and broken down to release CO2; enter Calvin cycle; glucose produced.

32
Q

Effects on the rate of PHS

A
  • Light.
  • Temperature + pH.
  • Carbon dioxide.
  • Water.
  • Enzyme inhibitation.
33
Q

Light (PHS)

A

Light increase = PHS increase (to a certain point - plateaus).

34
Q

Plateaus

A

No further change can occur; due to:
- Reach maximum possible rate of PHS.
- Other inputs or requirements for PHS is limiting the rate. (Limiting Factor; reactants needed for PHHS which there isn’t enough of).

35
Q

Temperature + pH (PHS)

A

PHS rate greatest at optimal temp.
Above optimal temp = denature of enzymes.

Optimal pH = enzymes function best; PHS fastest.
Below Optimal pH = enzymes denature.

36
Q

Carbon Dioxide (PHS)

A

High CO2 concentration = Increased PHS (til X (plateaus))
Low CO2 = limit PHS rate.

37
Q

Water (PHS)

A

Water stress; casued by droughts or hot weather periods.
Stomata close=limiting exchange of CO2 + O2(more abundant)–> therefore initiate photoresp.

Closed stomata = Low CO2, High O2; decreasing photosynthesis.

38
Q

Enzyme Inhibition

A

Influence function of genes; enzyme inhibitor; binds to and prevents an enzyme from functioning.
- Competitive
- Non-competitive

LOWER PHS RATE.

39
Q

Competitive inhibitor

A

Hinder enzyme by blocking the active site and preventing the substrate from binding.

40
Q

Non-competitive inhibitor

A

Hinders an enzyme by binding to an allosteric site and changing the shape of the active site preventing the substrate from binding.

41
Q

CRISPR in Agriculture.

A
  • Edit genome of agricultural crops.
    Therefore; increasing the amount of crops grown to meet the needs of a growing population.
    Gene editing = maximise crop productivity.
42
Q

How CRIPSR improves PHS rate and crop yields.

A

Engineer crops that bypass photorespiration,
Improve..
- Target RuBisCO function directly
- Edit the function of chloroplast to become more efficient
- Target stomata to reduce water loss.

43
Q

Cellular respiration

A

Cells create usable energy to breakdown large molecules and produce ATP.
Occurs via 2 biochemical pathways:
- Aerobic
- Anaerobic

44
Q

Aerobic Respiration

A

Occurs in the presence of oxygen, releasing more energy but slowly.
Consists of 3 stages.

45
Q

3 Stages of Aerobic Respiration

A
  • Glycolysis
  • Krebs Cycle
  • Electron transport chain (ETC)
46
Q

Glycolysis

A

Occurs in the cytosol

Inputs:
- Glucose
- 2 ADP + 2 Pi
- 2 NAD+ and 2 H+

Outputs:
- 2 pyruvate
- 2 ATP
- 2 NADH

Energy is released to be used by the cell.

47
Q

Role of the Krebs Cycle

A

To generate high-energy electrons and proton carriers (NADH and FADH2) that can be used in ETC.

48
Q

Linking Glycolysis and Krebs

A
  • Pyruvate is transported to mitochondria and combines with coenzyme A to create acetyl-CoA
49
Q

Krebs cycle

A

Occurs in the mitochondrial matrix

Inputs:
- 2 acetyl-CoA (derived from 2 pyruvate).
- 2 ADP + 2 Pi
- 6 NAD+ and 6 H+
- 2 FAD + 4 H+

Outputs:
- 4 CO2
- 2 ATP
- 6 NADH
- 2 FADH2

50
Q

Electron Transport chain

A

Occurs in the inner membrane of the mitochondria (cristae).

Inputs:
- 6 O2 + 12H+
- 26/28 ADP + 26/28 Pi
- 10 NADH
- 2 FADH2

Outputs:
- 6 H2O
- 26/28 ATP
- 10 NAD+ and 10H+
- 2 FAD + 4H+

51
Q

Enzymes + co-enzymes in cellular respiration

A

Catalyse reactions of cellular respiration and allow them to proceed at higher rates.

52
Q

Unloaded enzymes

A

ADP, NAD+ and FAD

53
Q

Loaded enzymes

A

ATP, NADH and FADH2

54
Q

Anaerobic Fermentation

A

Occurs in the absence of oxygen and releases less energy but quickly.
Stages:
- Glycolysis
- Lactic acid fermentation (animals) or ethanol fermentation (yeast).

55
Q

Anaerobic Fermentation in animals

A

Undertake this due to insufficient oxygen availability.
- Glycolysis

glucose -> 2pyruvate ->2lactic acids.
|. |
2ADP+Pi ->2ATP.
2NAD+ -> 2NADH —- >2NADH ->2NAD+

56
Q

Ethanol fermentation (yeast)

A

Also, involves glycolysis but instead pyruvate —> ethanol + CO2.

glucose -> 2pyruvate -> 2 ethanol + CO2
|. |
2ADP+Pi ->2ATP.
2NAD+ -> 2NADH —-> 2NADH ->2NAD+

57
Q

Factors influencing the rate of cellular respiration

A
  • Glucose
  • Temperature
  • O2 Concentration.
58
Q

Factors influencing the rate of cellular respiration
GLUCOSE

A

Increase glucose = increase rate of cell resp.
Decrease glucose = decrease rate of cell resp.

59
Q

Factors influencing the rate of cellular respiration
OXYGEN

A

High O2 = increased rate of aerobic respiration.
Low O2 = switch to anaerobic respiration.
No O2 = no cell resp.

1/2 O2 + 2e- + 2H+ —-> H2O

60
Q

Factors influencing the rate of cellular respiration
TEMPERATURE

A

cooler temp = less enzyme substrate collisions lowering cell resp rate.
Optimal temp = enzyme activity and cell resp will increase til max.
Above temp = denatured enzymes; negative impact on cell resp rate.

61
Q

Biomass

A

Organic material from living things

62
Q

Biofuel

A

Fuel derived from bio-mass (organic material)

63
Q

Biofuel production steps

A
  1. Deconstruction
  2. Digestion
  3. Anaerobic or ethanol fermentation.
  4. Purification + Hydration.
64
Q

Deconstruction (Biofuel)

A

Enzymes, acid and heat are used to crush the biomass.

65
Q

Digestion (Biofuel)

A

Simple enzymes are added to break down cell walls and starch into simple sugars such as glucose.

66
Q

Anaerobic or ethanol fermentation. (Biofuel)

A

Microorganisms (yeast + bacteria) produce ethanol + CO2.

67
Q

Purification + Dehydration (Biofuel)

A

Of Ethanol so that it is useable, as a liquid fuel.

68
Q

Benefits of Biofuel

A

Renewable
Many materials can be used, eg:
- Corn.
- Garbage.
- Sewage.
- Landfill

69
Q

Drawbacks of Biofuel

A
  • High-sugar products (many foods) are easier to make biofuels from.
  • Low sugar options are costly to process into biofuel.
  • Land requirements to allow biomass time to ferment.
  • Efficiency is low. (Transportation of biomass is energy expensive).

Biology 3/4 (6 decks)

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