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Photosynthesis And Respiration Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is an autotroph?

A

Type of nutrition where organic molecules are synthesised from inorganic molecules

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2
Q

What is a heterotroph

A

Type of nutrition where complex organic molecules are digested into smaller molecules

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3
Q

What is the granum

A

Inner part of chloroplasts made of thylakoid membranes, where the light dependent stage of photosynthesis takes place

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4
Q

What is the thylakoid

A

Flattened membrane bound sac found inside chloroplasts, contains photosynthetic pigments and site of light dependent stage in photosynthesis

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5
Q

What is the stroma

A

Fluid filled matrix of chloroplasts, where the light independent stage takes place

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6
Q

What are accessory pigments

A

Pigments which absorb different specific wavelengths of light and trap the energy associated with light

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7
Q

Examples of accessory pigments

A

Chlorophyll A and B, carotene and xanthophyll

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8
Q

What is an electron carrier

A

Molecules which can accept one or more electrons and then donate those to another carrier. Proteins in thylakoid membrane are electrons carriers and form electron transport chain or system. Ferredoxin, NAD and NADP also electron carriers

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9
Q

What does NADP stand for

A

Nicotinamide adenine dinucleotide phosphate

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10
Q

What is NADP and example of

A

Coenzyme

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11
Q

What is photophosphorylation

A

Generation of ATP from ADP and inorganic phosphate in presence of light

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12
Q

What is the Calvin cycle

A

Metabolic pathway of light independent stage. Occurs in eukaryotic cells in the stroma of chloroplasts where co2 fixed with products of light dependent stage to make organic compounds.

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13
Q

Where are photosystems found

A

Thylakoids

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14
Q

What is the peak absorption of photo system 1

A

700nm

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15
Q

What is the peak absorption of photo system 2

A

680 nm

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16
Q

What is the advantage of having different photosynthetic pigments

A

They have different peak absorption meaning at different types of the day, photosynthesis is still efficient at different light levels

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17
Q

What connects granum

A

Intergranal lamellae

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18
Q

How are chloroplasts adapted

A

Have many grana which provides large SA for :
- distribution of photosystems which have photosynthetic pigments which trap sunlight
- electron carriers and ATP synthase enzyme needed to convert light energy to ATP

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19
Q

What holds the photo system in place

A

Proteins embedded in the thylakoid membrane

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20
Q

Why is the grana surrounded by stroma

A

So products of light dependent stage can pass to stroma to be used in light independent stage

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21
Q

Describe the stages in the light dependent stage

A
  1. Light energy channeled to primary pigments by accessory pigment
  2. Light energy excited pair of electrons in PSII
  3. Electrons released from PSII captured by electron carrier
  4. Lost electrons replaced by photolysis
  5. When electron reaches electron carrier it becomes reduced to Fe2+ allowing it to become oxidised Fe3+ after passes electron down to next carrier
  6. As electrons move down chain, energy released
  7. Chemiosmosis - energy used to pump protons across thylakoid membrane to thylakoid space creating a proton gradient and chemiosmotic potential
  8. Electrons then captured by chlorophyll A in PSI which replaces electrons lost in PSI by excitation of light energy
  9. Ferredoxin accepts electrons from PS1, passing to NADP in stroma
  10. As protons accumulate in thylakoid space, proton gradient formed
  11. Protons diffuse down conc gradient through special membrane channels associated with ATP synthase enzyme causing ADP and inorganic phosphate to join forming ATP
  12. As protons flow through channel, they are accepted with electrons by NADP which is reduced . This reduction catalysed by enzyme NADP
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22
Q

Describe the production of ATP by substrate level phosphorylation in different stages of respiration with reference to number of ATP molecules produced

A

GLYCOLYSIS

2 ATP molecules produced by glycolysis
When triose biphosphate converted to pyruvate

4 ATP made but 2 used in glycolysis so net 2 ATP made

1 ATP made per turn of krebs cycle

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23
Q

What is the precise location of the link reaction within cells?

A

Mitochondrial matrix

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24
Q

Explain how having a high number of proton pores in the inner mitochondrial membrane would result in a person being less likely to gain weight

A

Proton pores result in protons leaking into mitochondrial matrix

This disrupt the chemiosmotic gradient resulting in a lower yield of ATP

So less ATP made from oxidative phosphorylation

More energy wasted as heat

Food not converted to ATP as efficiently

Less excess energy intake in diet

Fat stores may be respired for energy

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25
Q

Describe 2 quantitative changes in the inter membrane space after oxidative phosphorylation

A

PH decreases

Becomes more positively charged due to H+ ions

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26
Q

Outline how ATP is produced through chemiosmosis

A

Occurs in mitochondria

Involves inner membrane and matrix

Involves movement of hydrogen across membrane

Uses ATP synthase

H+ ions pumped out of matrix across membrane into inter membrane space

Proton gradient created

Cristae involved

ATP synthase produces ATP from ADP+P

H+ go from high to low concentration

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27
Q

Draw and annotate the light independent stage (Calvin cycle)

A

RuBP converted to GP as it is combined with CO2 (catalysed by RuBisCo). ATP then converted to ADP and Pi and energy used for molecular rearrangement. Reduced NADP gives up its H+ ion and is oxidised to create TP. ATP then converted to ADP and Pi again to create RuBp again.

Gp is used to make amino acids and proteins and can be converted to fatty acids.
Can combine with glycerol produced by TP to create lipids

TP used to make glycerol and lipids when combined with GP
Used to make starch as well

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28
Q

Where does glycolysis occur

A

Cytoplasm

29
Q

Describe the process of glycolysis

A
30
Q

What is the role of NAD

A

NAD is a molecule which helps dehydrogenase enzymes carry out oxidation reactions

NAD oxidises substrate molecules during glycolysis, link reaction and Krebs cycle

31
Q

What is the role of reduced NAD

A

Carries protons and electrons to cristae of mitochondria and delivers them to be used in oxidative phosphorylation for generation of ATP from ADP and Pi

32
Q

What are the three main stages of glycolysis

A

Phosphorylation
Glucose gains 2 phosphates to make hexose bisphosphate

Splitting of hexose bisphosphate into triose phosphate
Split into 2x 3C molecules

Oxidation of triose phosphate to pyruvate
Dehydrogenase enzymes aided by coenzyme NAD, remove hydrogens from triose phosphate

2 molecules of NAD accept the H+ ion and become reduced

33
Q

What are the products of glycolysis per molecule of glucose

A

2x ATP
2x reduced NAD
2x Pyruvate

34
Q

What are the stages of aerobic respiration

A

Glycolysis
Link reaction
Krebs cycle
Oxidative phosphorylation

35
Q

How are the pyruvate molecules from glycolysis transported to link reaction

A

Active transport

36
Q

What happens in the absence of oxygen after glycolysis

A

Pyruvate is converted , in the cytoplasm, to lactate or ethanol.
In these pathways, reduced NAD reoxidised
So glycolysis can continue to run
Generates two molecules of ATP for every glucose molecule

37
Q

Where do the krebs and link reaction take place

A

Mitochondrial matrix

38
Q

What does the mitochondrial matrix contain

A

Enzymes that catalyse stages of link and krebs

NAD and FAD

Oxaloacetate

Mitochondrial DNA

Mitochondrial ribosomes

39
Q

What does the outer membrane of a mitochondria contain

A

Proteins which form channels or carriers to allow molecules like pyruvate into mitochondria

40
Q

Electron transport chain

A
41
Q

How is pyruvate (formed by glycolysis) transported across the inner and outer mitochondrial membranes

A

By a Symport - transport protein which transports 2 ions or molecules in the same direction and into the matrix

42
Q

Briefly describe the link reaction

A

Carboxyl group removed (source of some of co2 in respiration)

Decarboxylation and dehydrogenation of pyruvate produces acetyl group

Acetyl group combines with CoA to form acetyl CoA

Coenzyme NAD becomes reduced

43
Q

What carries the acetyl group from the link reaction to the Krebs cycle

A

Coenzyme A

44
Q

Where does the Krebs cycle take place

A

Mitochondrial matrix like the link reaction

45
Q

What is the role of reduced NAD and reduced FAD in Krebs cycle

A

Carry the hydrogen atoms to cristae’s electron carrier chain where ATP is produced

46
Q

Per molecule of glucose, how many turns of the Krebs cycle is there

A

2

47
Q

What are the products produced in the link reaction per molecule of glucose

A

2x Reduced NAD

2x CO2

48
Q

What are the products produced in the Krebs cycle per molecule of glucose

A

6x reduced NAD

2x reduced FAD

4x CO2

2x ATP

(Remember there are 2x cycles of Krebs per molecule of glucose)

49
Q

What is the role of other substances in respiration

A

Fatty acids broken down to acetate which enter Krebs cycle via acetyl CoA

Glycerol converted to pyruvate and enter Krebs through link reaction

Amino acids delaminated and enter Krebs cycle directly or changed to pyruvate or acetyl CoA

50
Q

Theoretical amount of ATP per molecule in oxidative phosphorylation

A

30

51
Q

What is the real yield closer to

A

28

52
Q

Why is the theoretical yield rarely achieved

A

Some ATP used to actively transport pyruvate to mitochondria

ATP used in shuttle system that transports reduced NAD, made in glycolysis, into mitochondria

Some protons may leak out outer mitochondrial membrane

53
Q

What is the final electron acceptor In oxidative phosphorylation

A

Oxygen

54
Q

What is the equation in oxidative phosphorylation

A

4H+ + 4e- + O2 ——> 2H2O

55
Q

What happens if oxygen is absent in respiration

A

Oxygen can’t act as final electron acceptor in oxidative phosphorylation. Protons can’t combine with electrons and oxygen to form water after pass through ATP synthase channel

Conc of protons increases in matrix and reduces inner membrane proton gradient

Reduced NAD and FAD can’t unload hydrogen atoms and can’t be reoxidised

Krebs and link reaction stops

56
Q

What is the purpose of the fermentation pathways in anaerobic respiration

A

To reoxidise the reduced NAD

57
Q

Where do the fermentation pathways take place

A

In the cytoplasm

58
Q

What pathways to animals and fungi use

A

Animals use the lactate fermentation

Fungi use the ethanol fermentation pathway

59
Q

Describe the process of the ethanol fermentation pathway

A

Pyruvate is converted to ethanal through decarboxylation (catalysed by ethanal decarboxylase)

Ethanal then accepts hydrogen atom from reduced NAD and becomes reduced to ethanol

60
Q

What happens to the reduced NAD in the ethanol fermentation pathway

A

Reoxidised and available to accept hydrogen atoms from triose phosphate allowing glycolysis to continue

61
Q

Where does the lactate fermentation pathway occur

A

In the mammalian muscle

62
Q

Describe the lactate fermentation pathway

A

Pyruvate made in glycolysis accepts hydrogen atoms from reduced NAD (catalysed by lactate dehydrogenase) and is converted to lactate

63
Q

What happens to lactate after the lactate fermentation pathway

A

Converted to pyruvate which will enter Krebs or link

Recycled to glucose and glycogen

64
Q

What would happen if lactate was not removed from the muscle tissues

A

PH would be lowered, inhibiting action of enzymes in glycolysis and muscle contraction

65
Q

Why are monosaccharides like fructose and galactose less effective than glucose as a respiratory substrate

A

Because they are monosaccharides they have to be converted to glucose by isomerase enzymes

66
Q

Why are disaccharides less effective than glucose as a respiratory substrate

A

They have to be hydrolysed and converted to glucose before they enter glycolysis

67
Q

Describe how lipids are used as a respiratory substrate

A

With energy from hydrolysis of ATP to AMP, each fatty acid combines with CoA

Fatty acid CoA complex transported to mitochondrial matrix where broken down into 2C acetyl groups, each attached to CoA

Beta oxidation pathway generates reduced NAD and reduced FAD

Acetyl groups released from CoA and enter Krebs cycle

68
Q

Describe how proteins are used as a respiratory substrate

A

Biology (8 decks)

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