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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
What can GP be used to create?
Amino acids Fatty acids
25
What can TP be used to create?
Glycerol Hexose sugars
26
What can glycerol and fatty acids create?
Lipids - used for membranes
27
What is the effect of an increase in light intensity on light-independent reaction?
- 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
What is the effect of a decrease in light intensity on light-independent reaction?
- GP cannot be reduced to TP - Lower concentration of RuBp, reducing the fixation of CO₂ and the formation of more GP
29
What is the light compensation point?
When rate of photosynthesis and respiration are equal
30
What is the effect of high CO₂ conc. on light-independent reaction?
- 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
What is the effect of low CO₂ conc. on light-independent reaction?
- 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
What is the effect of temperature on light-dependent reaction?
Has little effect as light-dependent reaction is not dependent on enzymes
33
What is the purpose of respiration?
To turn the many potential sources of energy and convert them to one usable form (ATP)
34
Is ATP a coenzyme>
35
Is ATP a coenzyme?
Yes
36
Which version of ribose do coenzymes use?
All coenzymes use the RNA version of ribose (i.e. not deoxyribose)
37
Which type of enzymes are used to oxidise molecules?
Dehydrogenase enzymes
38
Name 4 coenzymes involved in respiration
NAD FAD Coenzyme A ATP
39
Give the 4 stages of respiration
1. Glycolysis 2. Link Reaction 3. Krebs Cycle 4. Oxidative Phosphorylation
40
Describe the 4 stages of glycolysis
1. Phosphorylation 2. Splitting of hexose-1,6-bisphosphate 3. Oxidation of triose phosphate 4. Conversion of triose phosphate to pyruvate
41
Where in the cell does glycolysis occur?
Cell cytoplasm
42
What does substrate level phosphorylation refer to?
The addition of Pi to ADP
43
What is the net production of ATP during glycolysis?
Net 2 ATP molecules produced 4 molecules produced overall but 2 used.
44
How many molecules of NAD are produced during glycolysis?
2 molecules of NAD are produced.
45
How many molecules are produced during glycolysis?
2 molecules of pyruvate
46
Where do the Link reaction and Krebs cycle take place?
Mitochondrial matrix
47
What does the mitochondrial matrix contain?
- Enzymes - Molecules of coenzyme NAD - Oxaloacetate - Mitochondrial DNA - Mitochondrial ribosomes
48
Detail features of the inner mitochondrial membrane
- Impermeable to H⁺ ions - Folded into cristae - Contains electron carriers and ATP synthase
49
Details features of the outer mitochondrial membrane
- Contains protein channels to allow pyruvate to pass through - Other proteins act as enzymes
50
Summarise the products of the Link reaction AND Krebs cycle per molecule of glucose
- 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
What is Oxygen known as in oxidative phosphorylation?
Terminal electron acceptor
52
Outline the transductive effect present in both photosynthesis and oxidative phosphorylation
Eₖ from the Proton Motive Force is transferred into chemical energy via ATP Synthase to combine Pi and ADP to form ATP
53
Where does oxidative phosphorylation take place?
Mitochondrial matrix / Intermembranal space
54
Where do the H⁺ ions come from in oxidative phosphorylation?
NADH and FADH
55
Where does anaerobic respiration occur?
Cell cytoplasm
56
Why does anaerobic respiration occur?
To prolong glycolysis and the creation of a small amount of ATP when Oxygen is low
57
What are the two pathways of anaerobic respiration?
- Alcoholic fermentation - conversion of pyruvate to ethanol - Lactate fermentation - conversion of pyruvate to lactic acid
58
What is the net yield of ATP during aerobic respiration vs anaerobic respiration?
Aerobic respiration produces a net yield of 32 ATP molecules Anaerobic respiration produces a net yield of 2 ATP molecules
59
Outline the process of alcoholic fermentation
- Pyruvate is decarboxylated and produces ethanal - Ethanal is now the terminal electron acceptor - NAD
60
Outline the process of alcoholic fermentation
- 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
What type of metabolite is ethanol in alcoholic fermentation?
Primary metabolite - it builds up to become toxic
62
Outline the process of lactate fermentation
- 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
Why is the alcoholic fermentation pathway irreversible?
CO₂ is given off
64
What is the respiratory energy value for glucose?
16KJg⁻¹
65
What is the respiratory energy value for lipids?
39KJg⁻¹
66
What is the respiratory energy value for proteins?
17KJg⁻¹
67
Why do lipids have a higher respiratory energy value than carbohydrates and proteins?
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
Give the formula for the Respiratory Quotient (RQ)
RQ = Volume of CO₂ given off / Volume of O₂ taken in

A-Level Biology - OCR A (16 decks)

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