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A-Level Biology - OCR A > 5.17 Energy for Biological Processes > Flashcards

5.17 Energy for Biological Processes Flashcards

1
Q

Define autotroph

A

Organism which produces complex organic compounds from simple inorganic molecules from light or inorganic chemical reactions

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2
Q

Define heterotroph

A

Organisms which ingest and digest complex organic molecules through chemical reactions

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3
Q

Define chemoautotrophs

A

Organisms that make their own complex organic molecules through chemical reactions

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4
Q

What is the role of the inner membrane in the chloroplast?

A

Controls the movements of substances

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5
Q

What is the function of having many grana in a chloroplast?

A

Provides a large surface area

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6
Q

What is the function of the stroma in the chloroplast?

A

Contains enzymes for the light-dependent stage

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7
Q

Why are the stroma and the grana located close together?

A

Allows the stages of photosynthesis to pass materials

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8
Q

What are the two forms of chlorophyll a?

A

P680 and P700

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9
Q

What is the primary pigment?

A

Chlorophyll a

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10
Q

Give 2 examples of accessory pigments

A
  • Chlorphyll b
  • Carotenoids
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11
Q

Give 2 examples of carotenoids

A
  • Carotene
  • Xanthophyll
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12
Q

Where are photosynthetic pigments found?

A

Within the photosystems, in the thylakoid membrane

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13
Q

What are the 2 stages of the light-dependent stage?

A
  • Photophosphorylation
  • Photolysis
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14
Q

What is photophosphorylation?

A

The synthesis of ATP from ADP and Pi using light energy

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15
Q

What is photolysis?

A

Splitting of H₂O molecules to produce H⁺ ions and electrons

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16
Q

What is light energy absorbed by photosystems used for?

A
  • Making ATP from ADP and Pi (Photophosphorylation)
  • Making NADP-red from NADP (NADP + 2H⁺ → NADP-red
  • Photolysis
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17
Q

What is the role of water in the light-dependent stage?

A

Source of: - Electrons used to replace those lost by oxidised chlorophyll
- H⁺ ions used in chemiosmosis; they are accepted by NADP to form NADP-red

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18
Q

What is chemiosmosis?

A

Process of forming ATP by diffusing through the thylakoid membrane and ATP synthase

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19
Q

What is a proton motive force?

A

When the protons are caught by NADP in the stroma

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20
Q

Which photosystems does the light-dependent stage use?

A

Photosystem II and Photosystem I

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20
Q

Outline the process of the light-dependent stage

A
  1. Light hits PSII, excites pair of electrons which leave chlorophyll molecule
  2. These are passed along the electron transport chain and a little energy is released
  3. Meanwhile, light has struck PSI and a pair of electrons have been excited
  4. These electrons (with an H⁺ made at PSII by photolysis) join NADP - becomes NADP-red
  5. The electron from oxidised PSII replace the electrons lost from PSI
  6. H⁺ ions from water take part in chemiosmosis to make ATP - then caught by NADP in stroma - this is proton motive force.
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21
Q

What is cyclic phosphorylation?

A

Only uses PSI (P700)
Excited electrons pass to an electron acceptor and back to their original chlorophyll molecule
No photolysis of water and no NADP-red is generated
Small amounts of ATP are produced
Part of the light-dependent stage but also part of light-independent stage

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22
Q

What is the light-independent stage?

A
  • Does not require light
  • Driven and dependent on products from the light-dependent stage
  • Takes place in the stroma
  • Produces sugars which are then stored as starch
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23
Q

Outline the process of the calvin cycle

A
  1. RuBp - CO₂ is fixed via enzyme RuBisCo - Carboxylation
  2. This forms 2x GP
  3. GP is reduced to 2x TP - NADP-red is oxidised to NADP - ATD is changed to ADP + Pi
  4. TP is regenerated to RuBp and ATP is changed to ADP + Pi
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24
Q

What can GP be used to create?

A

Amino acids
Fatty acids

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25
Q

What can TP be used to create?

A

Glycerol
Hexose sugars

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26
Q

What can glycerol and fatty acids create?

A

Lipids - used for membranes

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27
Q

What is the effect of an increase in light intensity on light-independent reaction?

A
  • More light = more energy to excite electrons
  • More ATP and NADP-red produced
  • Used to reduce GP to TP
  • ATP also used to phosphorylate 5/6 TP molecules to RuBp
28
Q

What is the effect of a decrease in light intensity on light-independent reaction?

A
  • GP cannot be reduced to TP
  • Lower concentration of RuBp, reducing the fixation of CO₂ and the formation of more GP
29
Q

What is the light compensation point?

A

When rate of photosynthesis and respiration are equal

30
Q

What is the effect of high CO₂ conc. on light-independent reaction?

A
  • GP and TP levels are high as RuBp is able to be fixed to form GP
  • RuBp levels are low as it is fixed to from GP
31
Q

What is the effect of low CO₂ conc. on light-independent reaction?

A
  • RuBp levels are high as it cannot be fixed to form GP
  • GP and TP levels are low as they can be converted to form RuBp
32
Q

What is the effect of temperature on light-dependent reaction?

A

Has little effect as light-dependent reaction is not dependent on enzymes

33
Q

What is the purpose of respiration?

A

To turn the many potential sources of energy and convert them to one usable form (ATP)

34
Q

Is ATP a coenzyme>

35
Q

Is ATP a coenzyme?

36
Q

Which version of ribose do coenzymes use?

A

All coenzymes use the RNA version of ribose (i.e. not deoxyribose)

37
Q

Which type of enzymes are used to oxidise molecules?

A

Dehydrogenase enzymes

38
Q

Name 4 coenzymes involved in respiration

A

NAD
FAD
Coenzyme A
ATP

39
Q

Give the 4 stages of respiration

A
  1. Glycolysis
  2. Link Reaction
  3. Krebs Cycle
  4. Oxidative Phosphorylation
40
Q

Describe the 4 stages of glycolysis

A
  1. Phosphorylation
  2. Splitting of hexose-1,6-bisphosphate
  3. Oxidation of triose phosphate
  4. Conversion of triose phosphate to pyruvate
41
Q

Where in the cell does glycolysis occur?

A

Cell cytoplasm

42
Q

What does substrate level phosphorylation refer to?

A

The addition of Pi to ADP

43
Q

What is the net production of ATP during glycolysis?

A

Net 2 ATP molecules produced
4 molecules produced overall but 2 used.

44
Q

How many molecules of NAD are produced during glycolysis?

A

2 molecules of NAD are produced.

45
Q

How many molecules are produced during glycolysis?

A

2 molecules of pyruvate

46
Q

Where do the Link reaction and Krebs cycle take place?

A

Mitochondrial matrix

47
Q

What does the mitochondrial matrix contain?

A
  • Enzymes
  • Molecules of coenzyme NAD
  • Oxaloacetate
  • Mitochondrial DNA
  • Mitochondrial ribosomes
48
Q

Detail features of the inner mitochondrial membrane

A
  • Impermeable to H⁺ ions
  • Folded into cristae
  • Contains electron carriers and ATP synthase
49
Q

Details features of the outer mitochondrial membrane

A
  • Contains protein channels to allow pyruvate to pass through
  • Other proteins act as enzymes
50
Q

Summarise the products of the Link reaction AND Krebs cycle per molecule of glucose

A
  • 8 molecules of NADᵣₑₔ produced
  • 2 molecules of FADᵣₑₔ produced
  • 2 molecules of ATP produced via SLP
  • 6 molecules of CO₂ produced (as waste)
51
Q

What is Oxygen known as in oxidative phosphorylation?

A

Terminal electron acceptor

52
Q

Outline the transductive effect present in both photosynthesis and oxidative phosphorylation

A

Eₖ from the Proton Motive Force is transferred into chemical energy via ATP Synthase to combine Pi and ADP to form ATP

53
Q

Where does oxidative phosphorylation take place?

A

Mitochondrial matrix / Intermembranal space

54
Q

Where do the H⁺ ions come from in oxidative phosphorylation?

A

NADH and FADH

55
Q

Where does anaerobic respiration occur?

A

Cell cytoplasm

56
Q

Why does anaerobic respiration occur?

A

To prolong glycolysis and the creation of a small amount of ATP when Oxygen is low

57
Q

What are the two pathways of anaerobic respiration?

A
  • Alcoholic fermentation - conversion of pyruvate to ethanol
  • Lactate fermentation - conversion of pyruvate to lactic acid
58
Q

What is the net yield of ATP during aerobic respiration vs anaerobic respiration?

A

Aerobic respiration produces a net yield of 32 ATP molecules
Anaerobic respiration produces a net yield of 2 ATP molecules

59
Q

Outline the process of alcoholic fermentation

A
  • Pyruvate is decarboxylated and produces ethanal
  • Ethanal is now the terminal electron acceptor
  • NAD
60
Q

Outline the process of alcoholic fermentation

A
  • Pyruvate is decarboxylated and produces ethanal
  • Ethanal is now the terminal electron acceptor
  • NADᵣₑₔ is oxidised to NAD using a Hydrogen from ethanal
  • (NAD is now able to pick up Hs from glycolysis)
  • This produces ethanol
61
Q

What type of metabolite is ethanol in alcoholic fermentation?

A

Primary metabolite - it builds up to become toxic

62
Q

Outline the process of lactate fermentation

A
  • NADᵣₑₔ id oxidised to form NAD using a Hydrogen from pyruvate
  • Pyruvate is the terminal electron acceptor
  • Lactic acid is formed and broken down in the liver using oxygen
63
Q

Why is the alcoholic fermentation pathway irreversible?

A

CO₂ is given off

64
Q

What is the respiratory energy value for glucose?

A

16KJg⁻¹

65
Q

What is the respiratory energy value for lipids?

A

39KJg⁻¹

66
Q

What is the respiratory energy value for proteins?

A

17KJg⁻¹

67
Q

Why do lipids have a higher respiratory energy value than carbohydrates and proteins?

A

Lipids have more Hydrogens on the fatty acid chains and therefore form more H⁺ ions which create a larger chemiosmotic gradient during oxidative phosphorylation and therefore a larger PMF.

68
Q

Give the formula for the Respiratory Quotient (RQ)

A

RQ = Volume of CO₂ given off / Volume of O₂ taken in

A-Level Biology - OCR A (16 decks)

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