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

energy transfers in and between organisms Flashcards

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
Agricultural practices to maximise plant growth
- Growing plants under artificial lighting to maximise light intensity - heating in greenhouse to increase temperature - burning fuel to release CO2
26
Benefit of agricultural practices for plant growth
- 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
Products of LIR
Hexose sugar NADP - used in LDR
28
Stages of aerobic respiration
1) Glycolysis 2) Link reaction 3) Krebs cycle 4) Oxidative phosphorylation
29
Location of glycolysis
Cytoplasm
30
Glycolysis
- 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
Coenzymes
- 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
Products of glycolysis
Net gain of 2 ATP 2 reduced NAD 2 pyruvate molecules
33
How many ATP molecules does glycolysis produce
- 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
Location of the link reaction
Mitochondrial matrix
35
Link reaction
- 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
Products of the link reaction per glucose molecule
- 2 acetylcoenzyme A molecules - 2 carbon dioxide molecules released - 2 reduced NAD molecules
37
Location of the Krebs cycle
Mitochondrial matrix
38
Krebs cycle
Acetylcoenzyme A combines with 4C molecule to produce a 6C molecule - enters cycle - oxidation-reduction reactions
39
Products of the Krebs cycle per glucose
8 reduced coenzymes - 6 reduced NAD - 2 reduced FAD 2 ATP 4 carbon dioxide
40
Location of oxidative phosphorylation
Cristae of mitochondria
41
Mitochondria structure
Double membrane with inner membrane folded into cristae enzymes in matrix
42
Role of reduced coenzymes in oxidative phosphorylation
- 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
Role of electrons in oxidative phosphorylation
- 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
How is ATP made in oxidative phosphorylation
- Protons move down electrochemical gradient back into matrix via ATP synthase - ATP created - movement of H+ is chemiosmosis
45
Role of oxygen in oxidative phosphorylation
- 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
How would lack of oxygen affect respiration
- 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
Oxidation
Loss of electrons when a molecule gains hydrogen
48
Reduction
Gain of electrons a reaction where a molecule gains hydrogen
49
Location of anaerobic respiration
Cytoplasm glycolysis only source of ATP
50
Anaerobic respiration in plants & microbes
- 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
Anaerobic respiration animals
- 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
Other respiratory substances
Fatty acids and amino acids can enter the Krebs cycle for continued ATP synthesis
53
Lipids as respiratory substances
Glycerol from lipid hydrolysis converted to acetylcoenzyme A - can enter the Krebs cycle
54
Proteins as respiratory substances
Amino acids from protein hydrolysis can be converted to intermediates within Krebs cycle

Biology - Topic 5 (2 decks)

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