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BIOL 1105 > 10: Photosynthesis > Flashcards

10: Photosynthesis Flashcards

Module 2, Lesson 4

1
Q

Almost all life on Earth ultimately depends on…

A

Energy from the Sun

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2
Q

A process that produces oxygen is termed…

A

Oxygenic

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3
Q

List three groups of organisms that can perform photosynthesis.

A
  1. Cyanobacteria
  2. 7 types of algae
  3. Most plants
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4
Q

During photosynthesis…

A

Carbon dioxide, water, and sunlight are converted into glucose, water, and molecular oxygen.

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5
Q

The process of photosynthesis is very similar to ____, but in reverse.

A

Aerobic respiration

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6
Q

The oxidation of water and reduction of carbon dioxide is driven by…

A

The energy from the Sun

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7
Q

The metabolic processes in chloroplasts and mitochondria form a(n)…

A

Energy cycle

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8
Q

Photosynthesis uses the products of ____ as starting substrates.

A

Respiration

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9
Q

Aerobic respiration uses the products of ____ as starting substrates.

A

Photosynthesis

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10
Q

In plants, photosynthesis occurs in the…

A

Chloroplasts

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11
Q

In leaves, cells called ____ contain a large number of chloroplasts.

A

Mesophylls

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12
Q

Chloroplasts have a ____ membrane.

A

Triple

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13
Q

The inner membrane of a chloroplasts interact with…

A

The stroma
(an interior compartment)

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14
Q

The stroma contains…

A

Thylakoid discs

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15
Q

Thylakoid discs are stacked in columns called…

A

Grana

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16
Q

The thylakoid disks are separated from the stroma by the…

A

Thylakoid membrane

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17
Q

The area enclosed by the thylakoid membrane is called the…

A

Thylakoid space or lumen

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18
Q

The thylakoid space contains ____ and ____.

A

Photosynthetic pigments and protein complexes

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19
Q

List the two main stages of photosynthesis.

A
  1. Light-dependent reactions
  2. Light-independent reactions
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20
Q

Light-dependent reactions occur in the…

A

Thylakoids

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21
Q

Processes that occur during the light-dependent phase include…

(four)

A
  1. Capturing of solar energy
  2. Generation of ATP
  3. Reduction of NADP+ to NADPH
  4. Production of oxygen from water
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22
Q

Light-independent reactions take place in the…

A

Stroma

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23
Q

Processes that occur during the light-independent phase include…

(three)

A
  1. Carbon fixation
  2. Calvin cycle
  3. Production of organic molecules
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24
Q

____ are molecules that absorb visible light photons.

A

Pigments

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25
Q

A ____ is a packet of light that acts like a discrete bundle of energy.

A

Photon

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26
Q

A photon’s ____ is inversely proportional to its ____.

A

Energy ; wavelength

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27
Q

The ____ describes the process by which photons can remove electrons from molecules.

A

Photoelectric effect

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28
Q

What happens in a molecule if an incoming photon has precisely the right energy?

A
  1. The photon is absorbed
  2. Its energy is transfered to an electron
  3. The electron moves to a higher energy level
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29
Q

____ electrons are those that have received energy from a photon.

A

Excited

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30
Q

During photosynthesis, the pigments in a chloroplast act as…

A

Photoelectric devices

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31
Q

Each pigment has a characteristic…

A

Absorption spectra

(can only absorb a specific wavelength of light)

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32
Q

List the three main pigments found in chloroplasts.

A
  1. Chlorophyll A
  2. Chlorophyll B
  3. Carotenoids
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33
Q

The main pigment in plants is…

A

Chlorophyll A

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34
Q

Which wavelengths (colors) of light can chlorophyll A absorb?

A

Violet-blue and red

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35
Q

True or false:

Chlorophyll A is the only pigment that can directly convert light into chemical energy.

A

True

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36
Q

Chlorophyll B and carotenoids are considered…

A

Accessory pigments

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37
Q

Which wavelengths (colors) of light can chlorophyll B absorb?

A

Blue and red-orange

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38
Q

Which wavelengths (colors) of light can carotenoids absorb?

A

Blue and blue-green

39
Q

True or false:

Many plants appear green because they absorb green light.

A

False

Plants appear green because they reflect green light.

40
Q

Cells that contain carotenoids will often appear…

A

Orange

41
Q

In addition to their role in photosynthesis, carotenoids also function as…

A

Anti-oxidants

42
Q

Light is captured by the…

A

Photosystems

43
Q

What is a photosystem?

A

A complex of pigments and proteins on the surface of the membrane

44
Q

List the two components of a photosystem.

A

Antenna complex and the reaction center

45
Q

The ____ contains hundreds of accessory pigment molecules.

A

Antenna complex

46
Q

The function of the antenna complex is to…

A

Gather photons and feed light to the reaction center

47
Q

The ____ contains one or more chlorophyll A molecules.

A

Reaction center

48
Q

The function of the reaction center is to…

A

Excite electrons and transfer them to an electron acceptor

49
Q

In plants, ____ is the electron donor.

A

Water

50
Q

Chloroplasts contain ____ linked photosystems.

A

2

51
Q

The electrons from water are transferred to ____, which is then used to produce ____ and ____.

A

NADP+
NADPH
ATP

52
Q

The process of photosynthesis begins at….

A

Photosystem II

53
Q

List the major steps of the light-dependent phase of photosynthesis.

(seven steps)

A
  1. Photons are absorbed and electrons are excited
  2. Water is oxidized
  3. Electrons are transferred to the b6f complex
  4. The energy from electrons is used to create a proton gradient
  5. Electrons are transferred to photosystem I, where they are reenergized
  6. Electrons enter the electron transport chain
  7. Electrons are transferred to NADP+ to form NADPH
54
Q

For each pair of electrons from water, the light-dependent reactions produce…

A

1 NADPH
~1 ATP

55
Q

During photosynthesis, a proton gradient is created across the…

A

Thylakoid membrane

56
Q

When the proton gradient is created, the concentration is ____ in the thylakoid space than in the stroma.

A

Greater

57
Q

In addition to the electron transport chain, photosynthesis can also produce a proton gradient by…

A
  1. The release of protons from the oxidation of water
  2. The loss of protons due to NADPH generation
58
Q

True or false:

Chloroplasts can use ATP synthase to produce ATP.

A

True

59
Q

During ATP synthesis in a chloroplast, protons move down their gradient from the ____ to the ____.

A

Thylakoid space to the stroma

60
Q

List the two types of photophosphorylation.

A
  1. Non-cyclic
  2. Cyclic
61
Q

During non-cyclic photophosphorylation…

A

The electron pair from water is transferred to NADP+, generating NADPH and ATP.

62
Q

True or false:

Non-cyclic photophosphorylation produces enough energy to build organic molecules.

A

False

Cells must use cyclic photophosphorylation to do this.

63
Q

During cyclic photophosphorylation…

A

Cells short-circuit photosystem I to create a larger proton gradient and cycle electrons back to the b6f complex.

64
Q

Cyclic phosphorylation uses ____ to make ATP instead of NADPH.

A

High-energy electrons

65
Q

True or false:

A cell can switch between cyclic and non-cyclic photophosphorylation as needed.

A

True

66
Q

A major process that occurs during the light-independent phase is the…

A

Calvin cycle

67
Q

What is the Calvin cycle?

A

A biochemical pathway that enables carbon fixation

68
Q

During the Calvin cycle, the products of the light-independent phase are used to…

A

Convert inorganic CO2 to organic carbohydrates

69
Q

The Calvin cycle is also called…

A

C3 photosynthesis

70
Q

List the three phases of the Calvin cycle.

A
  1. Carbon fixation
  2. Reduction
  3. Regeneration of RuBP
71
Q

The Calvin cycle occurs in the…

A

Stroma

72
Q

During carbon fixation…

A

RuBP and CO2 are used to produce 2 molecules of PGA

73
Q

Carbon fixation is catalyzed by…

A

Rubisco
(an enzyme)

(possibly the most abundant enzyme on earth!)

74
Q

During the reduction phase of the Calvin cycle…

A

PGA is reduced to G3P, and some G3P is released from the cycle

75
Q

During the regeneration phase of the Calvin cycle…

A

Most of the G3P is used to make RuBP

75
Q

The Calvin cycle must take place ____ time(s) to incorporate enough carbon for a G3P molecule.

A

Three

76
Q

The Calvin cycle must take place ____ time(s) to have enough carbon for one glucose molecule.

A

Six

77
Q

True or false:

Glucose is a direct product of the Calvin cycle.

A

False

The Calvin cycle produces G3P, a component of glucose.

78
Q

For every six CO2 molecules that enter the Calvin cycle, ____ G3P molecules are released.

A

2

78
Q

Glucose is produced in the ____ using G3P.

A

Cytoplasm

79
Q

Cells may also convert glucose into ____ or ____.

A

Sucrose (for transport)
Starch (for long-term storage)

80
Q

List the two enzymatic activities of rubisco.

A
  1. Carboxylation
  2. Oxidation
81
Q

Under normal conditions, rubisco favors ____, which leads to…

A

Carboxylation ; carbon fixation

82
Q

Carboxylation is the addition of ____ to RuBP.

A

CO2

83
Q

Under hot, dry conditions, rubisco favors ____ which leads to…

A

Oxidation ; photorespiration

84
Q

Oxidation is the addition of ____ to RuBP, resulting in the release of ____.

A

O2 ; CO2

85
Q

At 25 degrees Celsius, carboxylation happens 4x more often that oxidation, so…

A

20% of fixed carbon is lost to photorespiration

86
Q

Photorespiration often results in hot, dry environments because…

A

Plants close their stomata to prevent water loss, which cuts of their supply of CO2 and traps O2 inside.

87
Q

Plants can minimize photorespiration using the..

A

C4 and CAM pathways

88
Q

Some plants can prevent photorespiration by…

A

Using PEP carboxylase to add CO2 to PEP, creating a 4-carbon molecule with more affinity for CO2 than rubsico

89
Q

C4 plants minimize photorespiration by…

A

Separating the C3 and C4 pathways into different cells.

90
Q

CAM plants minimize photorespiration by…

A

Using C4 pathways at night and C3 pathways during the day

91
Q
A

BIOL 1105 (22 decks)

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