photosynthesis and respiration Flashcards

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1
Q

Describe glycolysis

A

Glycolysis takes place in cytoplasm

Glucose phosphorylated
- using 2 phosphates from 2 ATP molecules
Hydrolysed to form 2 triose phosphate
(1x = glucose phosphate, 2x = hexose bisphosphate)
Triose phosphate oxidised (removal of hydrogen)
Hydrogen transferred to NAD to form NADH
2 pyruvate molecules made

Substrate level phosphorylation produces 2 ATP

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2
Q

Describe link reaction

A

Pyruvate is oxidised and decarboxylated
to form acetate
Hydrogen removed is attached to NAD to form NADH
CO2 released
Acetate is bound to Coenzyme A

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3
Q

Describe Krebs cycle

A

Occurs in the matrix of mitochondria

acetylcoenzyme A reacts with 4c molecule
- coenzyme A released (back to link)
= 6c molecule
decarboxylated and oxidised
- releases CO2 and reduces NAD to NADH
= 5c molecule
decarboxylated and oxidised again
- releases CO2 and reduces NAD to NADH
= 4c molecule
oxidised
- ATP released by substrate level phosphorylation
- NAD reduced to NADH
- FAD reduced to FADH
= 4c molecule again

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4
Q

Describe oxidative phosphorylation

A

Krebs cycle / link reaction produces NADH and FADH
happens in matrix and intermembrane space (space between inner and outer membrane)
chemiosmosis

  1. NADH and FADH oxidised into NAD and FAD
    - Releases hydrogen atoms - split into protons and electrons
  2. Electrons released pass along electron transport chain (made of electron carriers)
  3. electrons lose energy at each carrier, released
  4. energy used to pump protons from matrix to intermembrane space
  5. concentration of protons now higher in intermembrane space
    - forms electrochemical gradient
  6. protons move down gradient into matrix through ATP synthase
  7. synthesises ATP from ADP and Pi

electrons protons and oxygen left in matrix make water

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5
Q

Anaerobic respiration in animals (+ bacteria)

A

Forms lactate and NAD

  1. Glycolysis
  2. Pyruvate reduced to lactate
    Uses NADH —> NAD oxidised

Production of NAD means glycolysis can continue in low oxygen
Small amount of ATP can be produced

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6
Q

Anaerobic respiration in plants and yeast

A

Forms ethanol and NAD

  1. glycolysis
  2. Pyruvate decarboxylated to ethanal (releases CO2)
  3. ethanal reduced to ethanol (oxidises NADH to NAD)
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7
Q

chemiosmosis

A

production of ATP from movement of H+ ions (protons) across a membrane, due to electrons in transport chain

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8
Q

products of glycolysis

A

2 ATP
2 NADH

2 pyruvate

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9
Q

products of link reaction

A

NADH
CO2 released
Acetyl CoA

no ATP

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10
Q

products of Krebs cycle

A

coenzyme A - used in link

NADH
FADH
used in OP

ATP
CO2

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11
Q

products of oxidative phosphorylation

A

NAD
FAD
ATP

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12
Q

3 respiratory substrates

A

Glucose
Amino acids
Glycerol and fatty acids from lipids

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13
Q

How are amino acids used as respiratory substrates?

A

Deaminated
= Pyruvate
Creates 4/5c compounds used in Krebs cycle

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14
Q

How are glycerol and fatty acids used a respiratory substrates?

A

Glycerol phosphorylated = triose phosphate
Fatty acids converted into acetyl

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15
Q

structure of mitochondria related to respiration

A

inner membrane
- site of electron transport chain
- location of ATP synthase

inter membrane space - between inner and outer
- low pH due to ions

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16
Q

Describe the light DEPENDANT stage

A

Occurs in thylakoid membrane
Makes ATP, NADPH (oxygen released)

Chlorophyll absorbs light energy
Excites electrons in chlorophyll
(photoionisation)
Electrons move along electron transfer chain
Energy from electrons released
Energy used to transport H+ ions into thylakoid space H+ ions diffuse through ATP synthase to make ATP ADP and Pi condense to form ATP
H+ ions combine with NADP to form NADPH

Photolysis of water produces protons, electrons and oxygen NADP reduced by electrons and protons
Oxygen released as a waste gas

17
Q

what is photoionisation?

A

chlorophyll absorb light energy
excites electrons - passed to ETC

18
Q

Describe the light INDEPENDENT stage

A

Occurs in stroma
Makes more RuBP and organic substances

Light independent reaction fixes CO2
CO2 fixed to ribulose bisphosphate (5c)
to make 2 molecules of glycerate-3-phosphate (3c)
The enzyme rubisco catalyses this reaction
Glycerate-3-phosphate becomes reduced.
to form 2 molecules of triose phosphate
using NADPH from the light dependent reaction
using ATP from the light dependent reaction
5/6 of the triose phosphate is converted into ribulose bisphosphate.
1/6 of the triose phosphate is converted into organic substances eg glucose.

19
Q

uses of organic substances made in photosynthesis

A

used in respiration
converted to cellulose for cell wall
converted to starch for storage

20
Q

limiting factors in photosynthesis

A

light intensity
carbon dioxide concentration
temperature

21
Q

how does light intensity affect photosynthesis?

A

rate increases as light intensity increases

creates more energy = faster light dependant
therefore more products for light independent

graph: increases until plateau, carbon dioxide or temperature is a limiting factor

22
Q

how does carbon dioxide concentration affect photosynthesis?

A

rate increases as concentration increases

required in light independent
- combines with ribulose bisphosphate
more carbon = faster this happens

graph: increases until plateau, light intensity or temperature limiting

23
Q

how does temperature affect photosynthesis?

A

rate increases as temperature increases

reaction controlled by enzymes
- eg rubisco in catalyses reaction between carbon dioxide and ribose bisphosphate
(little effect on light dependant, driven by suns energy instead)

increases until certain point
- enzymes denture

24
Q

effects on agricultural practices

A

maintain environment to increase growth and therefore yield

CO2 generators and monitors supply carbon dioxide

glass allows natural light and lamps are used during the night

glasshouses trap energy from sunlight
heating and cooling systems also used to maintain temperature

25
Q

products of dependant used in independent

A

energy from ATP
reduced NADP

26
Q

adaptations of chloroplasts for dependant

A

thylakoid membranes contain enzymes, carriers and pigments needed

membrane of grant = large surface area of thylakoid membrane

27
Q

adaptations of mitochondria for respiration

A

cristae (folds)
= large surface area for carriers and ATP synthase

larger/more mitochondria = active, more energy can be released

28
Q

oxygen

A

oxygen acts a final electron acceptor

allows NADH and FADH to be oxidised

29
Q

why do plants have multiple photosynthetic pigments?

A

each pigment absorbs different wavelength of light
= increases range of wavelengths a plant can absorb