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Photosynthesis > T > Flashcards

T Flashcards

1
Q

What are chloroplasts?

A

Chloroplasts are the organelles in plant cells where photosynthesis occurs

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2
Q

What surrounds each chloroplast?

A

A double-membrane envelope

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3
Q

What is the fluid inside chloroplasts called?

A

Stroma

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4
Q

What stage of photosynthesis occurs in the stroma?

A

Light-independent stage

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5
Q

What are thylakoids?

A

Fluid-filled sacs that stack to form structures known as grana

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6
Q

What is the function of the thylakoid membranes?

A

Site of the light-dependent stage of photosynthesis

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7
Q

What do the membranes of the grana provide?

A

A large surface area to increase the number of light-dependent reactions

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8
Q

What is produced during the light-dependent stage?

A

Reduced NADP and ATP

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9
Q

What process is used to produce ATP in the light-dependent stage?

A

Photophosphorylation

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10
Q

What is the Calvin cycle?

A

Reactions in the light-independent stage that produce complex organic molecules

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11
Q

List some carbohydrates produced during photosynthesis.

A
  • Starch (for storage)
  • Sucrose (for translocation)
  • Cellulose (for making cell walls)
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12
Q

What role do pigments play in chloroplasts?

A

They absorb different wavelengths of light

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13
Q

Where are the photosynthetic pigments located?

A

In the thylakoid membranes

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14
Q

What is the primary purpose of the light-dependent reactions?

A

To produce ATP and reduced NADP

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15
Q

True or False: The light-independent stage occurs in the thylakoids.

A

False

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16
Q

Fill in the blank: The _______ is the fluid that fills the chloroplasts and surrounds thylakoids.

A

Stroma

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17
Q

What are grana?

A

Stacks of thylakoids

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18
Q

What are stroma lamellae?

A

Membranous channels that connect the grana

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19
Q

What type of ribosomes are found in the stroma?

A

70S ribosomes

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20
Q

What does the loop of DNA in the stroma code for?

A

Some chloroplast proteins

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21
Q

What is the significance of the arrangement of pigment molecules in thylakoids?

A

Ensures maximum light capture

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22
Q

What is the primary pigment reaction center in a photosystem?

A

The site where energy is transferred to initiate photosynthesis

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23
Q

What is photolysis?

A

The process of breaking down water to produce electrons for the light-dependent reactions

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24
Q

How is energy from ATP used in the Calvin cycle?

A

To convert carbon dioxide into organic molecules

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25
Q

What is the difference between light-dependent and light-independent reactions?

A

Light-dependent reactions require light and occur in thylakoids, while light-independent reactions do not require light and occur in the stroma

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26
Q

What are thylakoids?

A

Thylakoids are structures that absorb different wavelengths of light and stack to form granum.

Thylakoids are essential for the light-dependent reactions of photosynthesis.

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27
Q

What structures do thylakoids form when stacked?

A

Grana (singular - granum)

Grana are important for increasing the surface area for light absorption.

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28
Q

What is the function of the thylakoid membrane system?

A

To provide a large number of pigment molecules arranged to absorb light effectively.

This arrangement ensures maximum light absorption necessary for photosynthesis.

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29
Q

What are light-harvesting clusters in thylakoids called?

A

Photosystems

Photosystems are essential for capturing and transferring light energy.

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30
Q

How are pigment molecules arranged in a photosystem?

A

In funnel-like structures in the thylakoid membrane.

This arrangement facilitates energy transfer to the primary pigment reaction center.

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31
Q

Where does the light-dependent stage of photosynthesis occur?

A

In the thylakoid membranes and thylakoid spaces.

This stage requires pigments, enzymes, and electron carriers.

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32
Q

What colors do chlorophylls reflect, causing plants to appear green?

A

Green light

Chlorophylls absorb blue-violet and red light, reflecting green.

33
Q

What is an absorption spectrum?

A

A graph showing the absorbance of different wavelengths of light by a particular pigment.

It helps to identify which wavelengths are absorbed by pigments like chlorophyll.

34
Q

What is an action spectrum?

A

A graph showing the rate of photosynthesis at different wavelengths of light.

It indicates which wavelengths are most effective for photosynthesis.

35
Q

What is the relationship between absorption spectra and action spectra?

A

There is a strong correlation, with both showing peaks at blue-violet and red regions and a trough in the green-yellow region.

This relationship highlights the effectiveness of certain wavelengths in photosynthesis.

36
Q

What is chromatography?

A

An experimental technique used to separate mixtures of substances.

In photosynthesis, chromatography separates chloroplast pigments.

37
Q

What are the two common techniques for separating photosynthetic pigments?

A
  • Paper chromatography
  • Thin layer chromatography

Each technique has different mechanisms for component separation.

38
Q

What does the retardation factor (R) indicate?

A

The distance traveled by a component divided by the distance traveled by the solvent.

R values help identify pigments based on their solubility.

39
Q

Which pigments generally have the highest R values?

A

Carotenoids

Carotenoids usually have R values close to 1, indicating high solubility.

40
Q

What is photolysis in the context of photosynthesis?

A

The breakdown of water using light energy to produce hydrogen ions, electrons, and oxygen.

This process occurs in the thylakoid lumen.

41
Q

What is produced during photophosphorylation?

A

ATP

ATP is produced using a proton gradient and the enzyme ATP synthase.

42
Q

What are the types of photophosphorylation?

A
  • Cyclic photophosphorylation
  • Non-cyclic photophosphorylation

The type depends on the involvement of photosystems I and II.

43
Q

What is the primary pigment in Photosystem II?

A

P680

This pigment absorbs light at a wavelength of 680nm.

44
Q

What is the primary pigment of Photosystem II?

A

P680

Absorbs light at a wavelength of 680nm

45
Q

What process occurs at Photosystem II?

A

Photolysis of water

This is where water is split into hydrogen ions, electrons, and oxygen

46
Q

What is the primary pigment of Photosystem I?

A

P700

Absorbs light at a wavelength of 700nm

47
Q

Where does the light-dependent stage of photosynthesis take place?

A

Thylakoid membrane and thylakoid lumen

48
Q

What is cyclic photophosphorylation?

A

Involves Photosystem I only

Light is absorbed and electrons are recycled back to the chlorophyll

49
Q

What is the role of ATP in photosynthesis?

A

Used during the light-independent reactions

50
Q

What is chemiosmosis?

A

Movement of protons down their concentration gradient

Provides energy for ATP synthesis

51
Q

What are the two key differences between cyclic and non-cyclic photophosphorylation?

A

Cyclic involves only Photosystem I and does not produce reduced NADP

52
Q

What is non-cyclic photophosphorylation?

A

Involves both Photosystem I and Photosystem II

53
Q

What enzyme catalyzes the photolysis of water?

A

Oxygen-evolving complex

54
Q

What is produced as a waste product during the photolysis of water?

A

Oxygen

55
Q

What do the excited electrons from Photosystem I combine with to form reduced NADP?

A

Hydrogen ions and NADP

56
Q

What is the chemical equation for the photolysis of water?

A

2 H2O → 4H+ + 4e- + O2

57
Q

What is the function of the electron transport chain?

A

Transports excited electrons and releases energy

58
Q

Fill in the blank: The process of synthesizing ATP from ADP and inorganic phosphate is called ______.

A

Chemiosmosis

59
Q

True or False: Non-cyclic photophosphorylation produces ATP and reduced NADP.

A

True

60
Q

What is the initial energy source for ATP synthesis in photophosphorylation?

A

Light

61
Q

What happens to the de-energized electrons from Photosystem II?

A

They are taken up by Photosystem I

62
Q

What is the process of photophosphorylation?

A

Involves the active transport of protons across the thylakoid membrane.

63
Q

What process allows protons to move back across the thylakoid membrane?

A

Chemiosmosis.

64
Q

During photophosphorylation, protons are first actively transferred from the _______ to the thylakoid space.

A

stroma

65
Q

The Calvin Cycle is also known as the _______ stage of photosynthesis.

A

light-independent

66
Q

What are the main inputs from the light-dependent stage used in the Calvin Cycle?

A
  • ATP
  • Reduced NADP
67
Q

Name three complex organic molecules produced during the Calvin Cycle.

A
  • Starch
  • Sucrose
  • Cellulose
68
Q

The Calvin Cycle can take place in light or _______.

A

darkness

69
Q

What enzyme catalyzes the fixation of carbon dioxide in the Calvin Cycle?

A

Ribulose bisphosphate carboxylase (rubisco).

70
Q

What is the initial product formed when carbon dioxide combines with ribulose bisphosphate (RuBP)?

A

An unstable six-carbon compound.

71
Q

The six-carbon compound formed in the Calvin Cycle splits into two molecules of _______.

A

glycerate 3-phosphate (GP)

72
Q

Glycerate 3-phosphate (GP) is converted into _______ during the Calvin Cycle.

A

triose phosphate (TP)

73
Q

What is the role of ATP and reduced NADP in the reduction of glycerate 3-phosphate?

A

They provide energy and hydrogen.

74
Q

One-sixth of the triose phosphate (TP) molecules are used to produce useful _______ needed by the plant.

A

organic molecules

75
Q

Triose phosphates can condense to become _______ phosphates.

A

hexose

76
Q

What can glycerate 3-phosphate (GP) be used to produce?

A

Some amino acids.

77
Q

What is required for the regeneration of ribulose bisphosphate (RuBP)?

A

ATP.

78
Q

Which molecules are produced from triose phosphate (TP) in the Calvin Cycle?

A
  • Hexose phosphates
  • Lipids
  • Amino acids
79
Q

True or False: The Calvin Cycle requires direct energy from light to proceed.

A

False

Photosynthesis (1 decks)

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