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5 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Where does photosynthesis take place in eukaryotic plants?

A

Photosynthesis takes place within cell organelles called chloroplasts.

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2
Q

What surrounds chloroplasts?

A

Chloroplasts are surrounded by a double membrane.

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3
Q

Adaptations of a leaf

A

Large surface area to absorb as much sunlight as possible

Thin so short diffusion distance

Stomata that open and close

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4
Q

What are grana?

A

Grana are stacks of up to 100 disc-like structures called thylakoids where the light-dependent stage of photosynthesis takes place. Within the thylakoids

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5
Q

What is found within the thylakoids?

A

The photosynthetic pigment called chlorophyll is found within the thylakoids.

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6
Q

What are inter-granal lamellae?

A

Inter-granal lamellae are tubular extensions that join up with thylakoids in adjacent grana.

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7
Q

What is the stroma?

A

The stroma is a fluid-filled matrix where the light-independent stage of photosynthesis takes place.

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8
Q

What structures can be found within the stroma?

A

Within the stroma are a number of other structures such as starch grains.

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9
Q

What is the purpose of the light-dependent reaction of photosynthesis?

A

To add an inorganic phosphate (P,) molecule to ADP, making ATP and to split water into H* ions and OH ions through photolysis.

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10
Q

Define oxidation.

A

The process when a substance gains oxygen or loses hydrogen.

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11
Q

Define reduction.

A

The process when a substance loses oxygen or gains hydrogen.

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12
Q

What happens to electrons during oxidation?

A

Electrons are lost.

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13
Q

What happens to electrons during reduction?

A

Electrons are gained.

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14
Q

What is the relationship between oxidation and reduction?

A

They always take place together.

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15
Q

What occurs when a chlorophyll molecule absorbs light energy?

A

It boosts the energy of a pair of electrons, raising them to a higher energy level. These electrons are in an excited state

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16
Q

What is photoionisation?

A

The process by which chlorophyll becomes oxidized after losing a pair of electrons.

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17
Q

What role do electron carriers play in photosynthesis?

A

They take up the electrons that leave chlorophyll and pass them along in a series of oxidation-reduction reactions.

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18
Q

What is the chemiosmotic theory?

A

It explains the mechanism by which ATP is produced during photosynthesis.

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19
Q

How are protons pumped into the thylakoid chambers?

A

Using protein carriers in the thylakoid membrane called proton pumps.

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20
Q

What drives the process of pumping protons into the thylakoids?

A

Electrons released when water molecules are split by light during photolysis.

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21
Q

Fill in the blank: Oxidation can be described as the loss of _______ or gain of _______.

A

[electrons], [oxygen]

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22
Q

Fill in the blank: Reduction can be described as the gain of _______ or loss of _______.

A

[electrons], [oxygen]

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23
Q

True or False: Oxidation results in energy being taken in.

A

False

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24
Q

True or False: Reduction results in energy being given out.

A

False

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25
Q

What is photolysis?

A

The splitting of water molecules into H* ions and OH ions using light energy.

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26
Q

What is the significance of the electron transfer chain?

A

It allows electrons to lose energy at each stage, some of which is used to make ATP.

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27
Q

What is the process by which water is split using light energy in photosynthesis?

A

Photolysis of water

This process yields protons, electrons, and oxygen.

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28
Q

What increases the concentration of protons inside the thylakoid space?

A

Photolysis of water

This process produces protons that increase their concentration in the thylakoid space.

29
Q

What maintains a concentration gradient of protons across the thylakoid membrane?

A

Photolysis of water

It results in high proton concentration inside and low concentration in the stroma.

30
Q

How can protons cross the thylakoid membrane?

A

Through ATP synthase channel proteins

The membrane is impermeable to protons except through these channels.

31
Q

What are the small granules formed by ATP synthase channels on the membrane surface called?

A

Stalked granules

These structures facilitate the passage of protons.

32
Q

What process does the passage of protons through ATP synthase catalyze?

A

The combination of ADP with inorganic phosphate to form ATP

This is essential for energy production in photosynthesis.

33
Q

What is the result of the loss of electrons from chlorophyll when light strikes it?

A

Chlorophyll becomes short of electrons

This necessitates the replacement of electrons to continue absorbing light energy.

34
Q

What is the chemical equation representing the photolysis of water?

A

2H₂O → 4H⁺ + 4e⁻ + O₂

This equation shows the products of the reaction.

35
Q

Fill in the blank: The protons are actively transported into the thylakoid using energy from _______.

A

Electrons from chlorophyll

This process involves electron transport chains.

36
Q

True or False: The concentration of protons is higher in the stroma than in the thylakoid space.

A

False

The concentration of protons is higher in the thylakoid space.

37
Q

What is the main product of the light-dependent stage of photosynthesis?

A

Reduced NADP

Reduced NADP serves as a potential source of chemical energy for the plant.

38
Q

What happens to protons in the thylakoid space during photosynthesis?

A

They pass out through the ATP synthase channels and are taken up by NADP.

39
Q

What occurs when NADP takes up protons?

A

NADP becomes reduced.

40
Q

What is the role of reduced NADP in the light-independent reaction?

A

It carries electrons from chlorophyll molecules.

41
Q

What is a by-product of the photolysis of water during photosynthesis?

A

Oxygen.

42
Q

What happens to the oxygen produced during photosynthesis?

A

It is either used in respiration or diffuses out of the leaf as a waste product.

43
Q

Fill in the blank: The __________ is a channel through which protons pass out of the thylakoid space.

A

ATP synthase.

44
Q

True or False: The light-dependent stage of photosynthesis produces ATP and reduced NADP.

A

True.

45
Q

What is the significance of reduced NADP for plants?

A

It is a potential source of chemical energy.

46
Q

How does the process of photolysis relate to photosynthesis?

A

It produces oxygen as a by-product.

47
Q

What are the two main products produced during the light-dependent stage of photosynthesis?

A

ATP and reduced NADP.

48
Q

What is the primary function of the Calvin cycle?

A

To produce useful organic substances such as glucose

The Calvin cycle is also known as the light-independent reaction of photosynthesis.

49
Q

What is the starting molecule that carbon dioxide reacts with in the Calvin cycle?

A

Ribulose bisphosphate (RuBP)

RuBP is a 5-carbon sugar involved in the Calvin cycle.

50
Q

What enzyme catalyzes the reaction between carbon dioxide and ribulose bisphosphate?

A

Ribulose bisphosphate carboxylase (rubisco)

Rubisco is essential for the fixation of carbon dioxide in the Calvin cycle.

51
Q

What are the products of the reaction between carbon dioxide and RuBP?

A

Two molecules of glycerate 3-phosphate (GP)

GP is a 3-carbon acid produced during the Calvin cycle.

52
Q

What is the role of reduced NADP in the Calvin cycle?

A

To reduce glycerate 3-phosphate to triose phosphate (TP)

Reduced NADP is obtained from the light-dependent reactions.

53
Q

What type of sugar is triose phosphate (TP)?

A

A 3-carbon sugar

TP is an important product in the Calvin cycle and is used to form glucose.

54
Q

What energy source is used in the reduction of glycerate 3-phosphate?

A

ATP

ATP provides the necessary energy for the reduction process in the Calvin cycle.

55
Q

Fill in the blank: Carbon dioxide enters the leaf through _______.

A

stomata

Stomata are small openings on the leaf surface that allow gas exchange.

56
Q

What is the first step of the Calvin cycle?

A

Carbon dioxide diffuses into the leaf and reacts with RuBP

This step occurs in the stroma of the chloroplast.

57
Q

True or False: The Calvin cycle requires light to occur.

A

False

The Calvin cycle is known as the light-independent reaction.

58
Q

What is the main role of ribulose bisphosphate (RuBP) in the Calvin cycle?

A

RuBP acts as a carbon dioxide acceptor in the Calvin cycle

RuBP combines with carbon dioxide to initiate the process of carbon fixation.

59
Q

What happens to NADP in the light-dependent reaction?

A

NADP is reduced by accepting protons and electrons

This reduction process is crucial for the light-independent reactions.

60
Q

Fill in the blank: The light-independent reaction of photosynthesis takes place in the _______.

A

stroma of the chloroplasts

61
Q

What are some organic substances that triose phosphate molecules are converted into?

A
  • starch
  • cellulose
  • lipids
  • glucose
  • amino acids
  • nucleotides

These substances are essential for plant metabolism and structure.

62
Q

How do triose phosphate molecules contribute to the regeneration of ribulose bisphosphate?

A

Most triose phosphate molecules are used to regenerate RuBP using ATP

This regeneration is necessary for the continuation of the Calvin cycle.

63
Q

What does the term ‘law of limiting factors’ refer to in the context of photosynthesis?

A

The rate of photosynthesis is determined by the factor that is in shortest supply

Only one factor can limit the process at any given time.

64
Q

What adaptations does the chloroplast have for carrying out the light-independent reaction?

A
  • The stroma contains all necessary enzymes
  • Membrane-bound stroma maintains a high concentration of enzymes and substrates
  • Stroma surrounds the grana for efficient diffusion of products
  • Contains DNA and ribosomes for quick protein manufacture

These adaptations enhance the efficiency of photosynthesis.

65
Q

True or False: The products of the light-dependent reaction cannot diffuse into the stroma.

A

False

The products can readily diffuse into the stroma from the grana.

66
Q

What is the significance of the stroma’s fluid environment?

A

It allows for a high concentration of enzymes and substrates to be maintained

This specialized environment is crucial for facilitating the chemical reactions of photosynthesis.

67
Q

Fill in the blank: The process of photosynthesis is complex and affected by multiple factors, but the rate is primarily controlled by the factor with the _______.

A

lowest availability

68
Q

What is produced as a result of the light-dependent reactions of photosynthesis?

A

ATP and reduced NADP

These products are essential for the light-independent reactions.

Biology (8 decks)

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