10: Photosynthesis Flashcards
Module 2, Lesson 4 (93 cards)
1
Q
Almost all life on Earth ultimately depends on…
A
Energy from the Sun
2
Q
A process that produces oxygen is termed…
A
Oxygenic
3
Q
List three groups of organisms that can perform photosynthesis.
A
- Cyanobacteria
- 7 types of algae
- Most plants
4
Q
During photosynthesis…
A
Carbon dioxide, water, and sunlight are converted into glucose, water, and molecular oxygen.
5
Q
The process of photosynthesis is very similar to ____, but in reverse.
A
Aerobic respiration
6
Q
The oxidation of water and reduction of carbon dioxide is driven by…
A
The energy from the Sun
7
Q
The metabolic processes in chloroplasts and mitochondria form a(n)…
A
Energy cycle
8
Q
Photosynthesis uses the products of ____ as starting substrates.
A
Respiration
9
Q
Aerobic respiration uses the products of ____ as starting substrates.
A
Photosynthesis
10
Q
In plants, photosynthesis occurs in the…
A
Chloroplasts
11
Q
In leaves, cells called ____ contain a large number of chloroplasts.
A
Mesophylls
12
Q
Chloroplasts have a ____ membrane.
A
Triple
13
Q
The inner membrane of a chloroplasts interact with…
A
The stroma
(an interior compartment)
14
Q
The stroma contains…
A
Thylakoid discs
15
Q
Thylakoid discs are stacked in columns called…
A
Grana
16
Q
The thylakoid disks are separated from the stroma by the…
A
Thylakoid membrane
17
Q
The area enclosed by the thylakoid membrane is called the…
A
Thylakoid space or lumen
18
Q
The thylakoid space contains ____ and ____.
A
Photosynthetic pigments and protein complexes
19
Q
List the two main stages of photosynthesis.
A
- Light-dependent reactions
- Light-independent reactions
20
Q
Light-dependent reactions occur in the…
A
Thylakoids
21
Q
Processes that occur during the light-dependent phase include…
(four)
A
- Capturing of solar energy
- Generation of ATP
- Reduction of NADP+ to NADPH
- Production of oxygen from water
22
Q
Light-independent reactions take place in the…
A
Stroma
23
Q
Processes that occur during the light-independent phase include…
(three)
A
- Carbon fixation
- Calvin cycle
- Production of organic molecules
24
Q
____ are molecules that absorb visible light photons.
A
Pigments
25
A ____ is a packet of light that acts like a discrete bundle of energy.
Photon
26
A photon's ____ is inversely proportional to its ____.
Energy ; wavelength
27
The ____ describes the process by which photons can remove electrons from molecules.
Photoelectric effect
28
What happens in a molecule if an incoming photon has precisely the right energy?
1. The photon is absorbed
2. Its energy is transfered to an electron
3. The electron moves to a higher energy level
29
____ electrons are those that have received energy from a photon.
Excited
30
During photosynthesis, the pigments in a chloroplast act as...
Photoelectric devices
31
Each pigment has a characteristic...
Absorption spectra
(can only absorb a specific wavelength of light)
32
List the three main pigments found in chloroplasts.
1. Chlorophyll A
2. Chlorophyll B
3. Carotenoids
33
The main pigment in plants is...
Chlorophyll A
34
Which wavelengths (colors) of light can chlorophyll A absorb?
Violet-blue and red
35
# True or false:
Chlorophyll A is the only pigment that can directly convert light into chemical energy.
True
36
Chlorophyll B and carotenoids are considered...
Accessory pigments
37
Which wavelengths (colors) of light can chlorophyll B absorb?
Blue and red-orange
38
Which wavelengths (colors) of light can carotenoids absorb?
Blue and blue-green
39
# True or false:
Many plants appear green because they absorb green light.
False
Plants appear green because they **reflect** green light.
40
Cells that contain carotenoids will often appear...
Orange
41
In addition to their role in photosynthesis, carotenoids also function as...
Anti-oxidants
42
Light is captured by the...
Photosystems
43
What is a photosystem?
A complex of pigments and proteins on the surface of the membrane
44
List the two components of a photosystem.
Antenna complex and the reaction center
45
The ____ contains hundreds of accessory pigment molecules.
Antenna complex
46
The function of the antenna complex is to...
Gather photons and feed light to the reaction center
47
The ____ contains one or more chlorophyll A molecules.
Reaction center
48
The function of the reaction center is to...
Excite electrons and transfer them to an electron acceptor
49
In plants, ____ is the electron donor.
Water
50
Chloroplasts contain ____ linked photosystems.
2
51
The electrons from water are transferred to ____, which is then used to produce ____ and ____.
NADP+
NADPH
ATP
52
The process of photosynthesis begins at....
Photosystem II
53
List the major steps of the light-dependent phase of photosynthesis.
| (seven steps)
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
For each pair of electrons from water, the light-dependent reactions produce...
1 NADPH
~1 ATP
55
During photosynthesis, a proton gradient is created across the...
Thylakoid membrane
56
When the proton gradient is created, the concentration is ____ in the thylakoid space than in the stroma.
Greater
57
In addition to the electron transport chain, photosynthesis can also produce a proton gradient by...
1. The release of protons from the oxidation of water
2. The loss of protons due to NADPH generation
58
# True or false:
Chloroplasts can use ATP synthase to produce ATP.
True
59
During ATP synthesis in a chloroplast, protons move down their gradient from the ____ to the ____.
Thylakoid space to the stroma
60
List the two types of photophosphorylation.
1. Non-cyclic
2. Cyclic
61
During non-cyclic photophosphorylation...
The electron pair from water is transferred to NADP+, generating NADPH and ATP.
62
# True or false:
Non-cyclic photophosphorylation produces enough energy to build organic molecules.
False
Cells must use cyclic photophosphorylation to do this.
63
During cyclic photophosphorylation...
Cells short-circuit photosystem I to create a larger proton gradient and cycle electrons back to the b6f complex.
64
Cyclic phosphorylation uses ____ to make ATP instead of NADPH.
High-energy electrons
65
# True or false:
A cell can switch between cyclic and non-cyclic photophosphorylation as needed.
True
66
A major process that occurs during the light-independent phase is the...
Calvin cycle
67
What is the Calvin cycle?
A biochemical pathway that enables carbon fixation
68
During the Calvin cycle, the products of the light-independent phase are used to...
Convert inorganic CO2 to organic carbohydrates
69
The Calvin cycle is also called...
C3 photosynthesis
70
List the three phases of the Calvin cycle.
1. Carbon fixation
2. Reduction
3. Regeneration of RuBP
71
The Calvin cycle occurs in the...
Stroma
72
During carbon fixation...
RuBP and CO2 are used to produce 2 molecules of PGA
73
Carbon fixation is catalyzed by...
Rubisco
(an enzyme)
| (possibly the most abundant enzyme on earth!)
74
During the reduction phase of the Calvin cycle...
PGA is reduced to G3P, and some G3P is released from the cycle
75
During the regeneration phase of the Calvin cycle...
Most of the G3P is used to make RuBP
75
The Calvin cycle must take place ____ time(s) to incorporate enough carbon for a G3P molecule.
Three
76
The Calvin cycle must take place ____ time(s) to have enough carbon for one glucose molecule.
Six
77
# True or false:
Glucose is a direct product of the Calvin cycle.
False
The Calvin cycle produces G3P, a component of glucose.
78
For every six CO2 molecules that enter the Calvin cycle, ____ G3P molecules are released.
2
78
Glucose is produced in the ____ using G3P.
Cytoplasm
79
Cells may also convert glucose into ____ or ____.
Sucrose (for transport)
Starch (for long-term storage)
80
List the two enzymatic activities of rubisco.
1. Carboxylation
2. Oxidation
81
Under normal conditions, rubisco favors ____, which leads to...
Carboxylation ; carbon fixation
82
Carboxylation is the addition of ____ to RuBP.
CO2
83
Under hot, dry conditions, rubisco favors ____ which leads to...
Oxidation ; photorespiration
84
Oxidation is the addition of ____ to RuBP, resulting in the release of ____.
O2 ; CO2
85
At 25 degrees Celsius, carboxylation happens 4x more often that oxidation, so...
20% of fixed carbon is lost to photorespiration
86
Photorespiration often results in hot, dry environments because...
Plants close their stomata to prevent water loss, which cuts of their supply of CO2 and traps O2 inside.
87
Plants can minimize photorespiration using the..
C4 and CAM pathways
88
Some plants can prevent photorespiration by...
Using PEP carboxylase to add CO2 to PEP, creating a 4-carbon molecule with more affinity for CO2 than rubsico
89
C4 plants minimize photorespiration by...
Separating the C3 and C4 pathways into different cells.
90
CAM plants minimize photorespiration by...
Using C4 pathways at night and C3 pathways during the day
91
