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Biology - Topic 5 > energy transfers in and between organisms > Flashcards

energy transfers in and between organisms Flashcards

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1
Q

Location of light dependent reaction

A

Thylakoid membranes of chloroplast

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2
Q

Location of light independent reaction

A

Stroma of chloroplast

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3
Q

Chloroplast structure

A
  • thylakoids stacked to form granum linked by lamella
  • stroma fluid
  • inner and outer membrane
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4
Q

Thylakoid membranes

A
  • Folded membranes containing photosynthetic proteins (chlorophyll)
  • embedded with transmembrane electron carrier proteins
  • involved in the LDRs
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5
Q

Chlorophyll

A
  • Located in proteins on thylakoid membranes
  • mix of coloured proteins that absorb light
  • different proportions of each pigment lead to different colours on leaves
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6
Q

Advantage of many pigments

A
  • Each pigment absorbs a different wavelength of visible light
  • many pigments maximises spectrum of visible light absorbed
  • maximum light energy taken in so more photoionisation and higher rate of photosynthesis
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7
Q

Light-dependent reaction (LDR)

A
  • First stage of photosynthesis
  • occurs in thylakoid membranes
  • uses light energy and water to create ATP and reduced NADP for LIR
  • involves photoionisation of chlorophyll, photolysis and chemiosmosis
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8
Q

Photolysis

A

Light energy absorbed by chlorophyll splits water into oxygen, H+ and e-
H2O –> 1/2 O2 + 2e- + 2H+

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9
Q

Products of photolysis

A
  • H+
    Picked up by NADP to form reduced NADP for LIR
  • e-
    passed along chain of electron carrier proteins
  • oxygen
    used in respiration or diffuses out leaf via stomata
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10
Q

Photoionisation of chlorophyll

A
  • Light energy absorbed by chlorophyll excites electrons so they move to a higher energy level and leave chlorophyll - some of the energy released is used to make ATP and reduced NADP
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11
Q

Chemiosmosis

A
  • Electrons that gained energy move along a series of electron carriers in thylakoid membrane
  • release energy as they go along which pumps protons across thylakoid membrane
  • electrochemical gradient made
  • protons pass back across via ATP synthase enzyme producing ATP down their conc. gradient
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12
Q

What happens to protons after chemiosmosis

A

Combine with co-enzyme NADP to become reduced NADP
- reduced NADP used in LIR

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13
Q

Products of LDR

A
  • ATP (used in LIR)
  • reduced NADP (used in LIR)
  • oxygen (used in respiration / diffuses out stomata)
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14
Q

Light independent reaction (LIR)

A
  • Calvin cycle
  • uses CO2, reduced NADP and ATP to form hexose sugar
  • occurs in stroma which contains the enzyme Rubisco
  • temperature-sensitive
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15
Q

Calvin cycle

A

RuBP combines with CO2 (rubisco)
to make 2 x GP
then using ATP and NADPH —> 2 x TP
then a hexose is released
then using ATP , RuBP is regenerated

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16
Q

RuBP

A

Ribulose Bisphosphate
5-carbon molecule

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17
Q

GP

A

Glycerate-3-phosphate
3-carbon molecule

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18
Q

TP

A

Triose phosphate
3-carbon molecule

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19
Q

Producing hexose sugar in LIR

A
  • Takes 6 cycles
  • glucose can join to form disaccharides (sucrose) or polysaccharides (cellulose)
  • can be converted to glycerol to combine with fatty acids to make lipids
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20
Q

Limiting factor

A

A factor which, if increased, the rate of the overall reaction also increases

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21
Q

Limiting factors of photosynthesis

A

Light intensity
CO2 concentration temperature

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22
Q

How light intensity limits photosynthesis

A

If reduced, levels of ATP and reduced NADP would fall
- LDR limited - less photolysis
and photoionisation
- GP cannot be reduced to TP in LIR

23
Q

How temperature limits photosynthesis

A
  • LIR inhibited - enzyme controlled (Rubisco)
  • up to optimum, more collisions and E-S complexes
  • above optimum, H-bonds in tertiary structure break, active site changes shape - denatured
24
Q

How CO2 concentration limits photosynthesis

A
  • If reduced, LIR inhibited
    less CO2 to combine with RuBP to form GP
  • less GP reduced to TP
  • less TP converted to hexose and RuBP regenerate
25
Q

Agricultural practices to maximise plant growth

A
  • Growing plants under artificial lighting to maximise light intensity
  • heating in greenhouse to increase temperature
  • burning fuel to release CO2
26
Q

Benefit of agricultural practices for plant growth

A
  • Faster production of glucose -> faster respiration
  • more ATP to provide energy for growth e.g. cell division + protein synthesis
  • higher yields so more profit
27
Q

Products of LIR

A

Hexose sugar
NADP - used in LDR

28
Q

Stages of aerobic respiration

A

1) Glycolysis
2) Link reaction
3) Krebs cycle
4) Oxidative phosphorylation

29
Q

Location of glycolysis

A

Cytoplasm

30
Q

Glycolysis

A
  • Substrate level phosphorylation
    2 ATP molecules add 2 phosphate groups to glucose
  • glucose phosphate splits into two triose phosphate (3C) molecules
  • both TP molecules are oxidised (reducing NAD) to form 2 pyruvate molecules (3C)
  • releases 4 ATP molecules
31
Q

Coenzymes

A
  • A molecule which aids / assists an enzyme
  • NAD and FAD in respiration both gain hydrogen to form reduced NAD (NADH) and reduced FAD (FADH)
  • NADP in photosynthesis gains hydrogen to form reduced NADP (NADPH)
32
Q

Products of glycolysis

A

Net gain of 2 ATP
2 reduced NAD
2 pyruvate molecules

33
Q

How many ATP molecules does glycolysis produce

A
  • 2 ATP molecules used to phosphorylate glycose to glucose phosphate
  • 4 molecules generated in oxidation of TP to pyruvate
  • net gain 2 ATP molecules
34
Q

Location of the link reaction

A

Mitochondrial matrix

35
Q

Link reaction

A
  • Reduced NAD and pyruvate are actively transported to matrix
  • pyruvate is oxidised to acetate (forming reduced NAD)
  • carbon removed and CO2 forms
  • acetate combines with coenzyme A to form acetylcoenzyme A (2C)
36
Q

Products of the link reaction per glucose molecule

A
  • 2 acetylcoenzyme A molecules
  • 2 carbon dioxide molecules released
  • 2 reduced NAD molecules
37
Q

Location of the Krebs cycle

A

Mitochondrial matrix

38
Q

Krebs cycle

A

Acetylcoenzyme A combines with 4C molecule to produce a 6C molecule - enters cycle
- oxidation-reduction reactions

39
Q

Products of the Krebs cycle per glucose

A

8 reduced coenzymes
- 6 reduced NAD
- 2 reduced FAD
2 ATP
4 carbon dioxide

40
Q

Location of oxidative
phosphorylation

A

Cristae of mitochondria

41
Q

Mitochondria structure

A

Double membrane with inner membrane folded into cristae enzymes in matrix

42
Q

Role of reduced coenzymes in oxidative phosphorylation

A
  • Accumulate in mitochondrial matrix, where they release their protons (H+) and electrons (e-)
  • regenerate NAD and FAD to be used in glycolysis/ link reaction / Krebs cycle
43
Q

Role of electrons in oxidative phosphorylation

A
  • Electrons pass down series of electron carrier proteins, losing energy as they move
  • energy released actively transports H+ from mitochondrial matrix to inter- membranal space
  • electrochemical gradient generated
44
Q

How is ATP made in oxidative
phosphorylation

A
  • Protons move down electrochemical gradient back into matrix via ATP synthase
  • ATP created
  • movement of H+ is chemiosmosis
45
Q

Role of oxygen in oxidative phosphorylation

A
  • Oxygen is the final electron acceptor in electron transport chain
  • oxygen combines with protons and electrons to form water
  • enables the electron transport chain to continue
46
Q

How would lack of oxygen affect respiration

A
  • Electrons can’t be passed along the electron transport chain
  • the Krebs cycle and link reaction stop because NAD and FAD (converted from reduced NAD/FAD as they release their H atoms for the ETC), cannot be produced
47
Q

Oxidation

A

Loss of electrons
when a molecule gains hydrogen

48
Q

Reduction

A

Gain of electrons
a reaction where a molecule gains hydrogen

49
Q

Location of anaerobic respiration

A

Cytoplasm
glycolysis only source of ATP

50
Q

Anaerobic respiration in plants & microbes

A
  • Pyruvate produced in glycolysis is reduced to form ethanol and CO2
  • pyruvate gains hydrogen from reduced NAD
  • reduced NAD oxidised to NAD so can be reused in glycolysis
  • 2 ATP produced
51
Q

Anaerobic respiration animals

A
  • Pyruvate produced in glycolysis is reduced to form lactate
  • pyruvate gains hydrogen from reduced NAD
  • reduced NAD oxidised to NAD so can be reused in glycolysis
  • 2 ATP produced
52
Q

Other respiratory substances

A

Fatty acids and amino acids can enter the Krebs cycle for continued ATP synthesis

53
Q

Lipids as respiratory substances

A

Glycerol from lipid hydrolysis converted to acetylcoenzyme A
- can enter the Krebs cycle

54
Q

Proteins as respiratory substances

A

Amino acids from protein hydrolysis can be converted to intermediates within Krebs cycle

Biology - Topic 5 (2 decks)

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