Photosynthesis Flashcards

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1
Q

What is photosynthesis

A
  • the process by which energy (in the form of light from the sun) is used to build complex organic molecules
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2
Q

Word equation for photosynthesis

A

carbon dioxide + water = glucose + oxygen

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3
Q

What are autotrophs

A

Organisms that can photosynthesis to produce their own complex molecules

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4
Q

What are heterotrophs

A

have to obtain complex organic molecules by eating other organisms

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5
Q

Key structural features of chloroplasts

A
  • double membrane
  • very flat- increases surface area to absorb light
  • thylakoids
  • grana/ granum
  • lamellae
  • stroma
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6
Q

What is a granum

A

A stack of thylakoids (fluid filled sacs formed by membranes)

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7
Q

What are lamellae

A
  • join grana together
  • bits of thylakoid membranes, membranous channels
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8
Q

What is the stroma

A
  • the fluid enclosed in a chloroplast
  • site of many chemical reactions
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9
Q

What is chlorophyll

A
  • pigment molecule that absorb different wavelengths of light
  • absorbs red and blue, reflects green
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10
Q

What are 4 main photosynthetic pigments

A
  • chlorophyll A
  • chlorophyll B
  • carotenoids
  • xanthophyll
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11
Q

Differences in roles of photosynthetic pigments

A
  • chlorophyll A is in the reaction centre where photosynthesis occurs
  • chlorophyll B, carotenoids, xanthophyll embedded in thylakoid membranes, joined to proteins, form light harvesting system
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12
Q

What is a photosystem

A

-the light harvesting system and reaction centre
- proteins and pigments collectively

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13
Q

Summary of the light dependent stage

A
  • occurs in thylakoid membranes
  • energy from sunlight is absorbed and used to form ATP
  • hydrogen from water is used to reduce NADP
  • Produces NADPH, ATP, oxygen
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14
Q

non-cyclic phosphorylation

A
  • involves PSI + PSII
  • electrons travel from PSII to PSI, losing electrons as they do so
  • electrons lost from PSII are replaced by photolysis
  • electrons from PSI pass down electron transport chain, form reduced NADP
  • electrons lost from PSI replaced with electrons from PSII
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15
Q

What is photolysis, what is the equation

A
  • light energy is used to split water
  • water => hydrogen + electrons + oxygen
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16
Q

Cyclic phosphorylation

A
  • involves PSI only
  • electrons leaving PSI return via electron carriers
  • ATP produced
17
Q

What cycle is involved in the light independent stage

A

Calvin cycle

18
Q

Where does the light independent stage occur

A

Stroma

19
Q

3 key molecules involved in the light independent stage

A
  • Triose phosphate (TP)
  • Ribulose phosphate (RuBp)
  • Glycerate 3 phosphate (GP)
20
Q

Overall products of the light independent stage

A
  • ADP + P
  • NADP
  • carbs/ sugars/ amino acids/ lipids
  • regeneration of RuBp
21
Q

Factors affecting photosynthesis

A
  • light intensity
  • carbon dioxide concentration
  • temperature
22
Q

How does light intensity affect photosynthesis

A
  • If light intensity is high, more ATP and NADPH are produced in the light dependent stage, so more ATP and NADPH enter the calvin cycle
  • Results in high GP, low TP and RuBp
23
Q

How does carbon dioxide concentration affects photosynthesis

A
  • increases the rate of carbon fixation in the Calvin cycle
  • results in less GP , less TP, increases RuBp
24
Q

How does temperature affect photosynthesis

A
  • at high temperatures, enzymes may denature, stomata may close causing less photosynthesis as less CO2, potential damage to all the membranes, resulting in less photosynthesis
25
Q
A