Chapter 5 Flashcards
(118 cards)
1
Q
Term/Front
A
Definition/Back
2
Q
What is photosynthesis?
A
Photosynthesis is the biological process where photoautotrophs capture light energy from the sun and convert it into chemical energy.
3
Q
What do plants use as inputs for photosynthesis?
A
Plants use carbon dioxide and water as inputs for photosynthesis.
4
Q
What is the primary product of photosynthesis?
A
The primary product of photosynthesis is glucose.
5
Q
What role do leaves play in photosynthesis?
A
Leaves are the main site of photosynthesis in plants and have a large surface area to maximize light absorption.
6
Q
What are mesophyll cells?
A
Mesophyll cells are the main cells in leaves that carry out photosynthesis.
7
Q
What is the function of chloroplasts?
A
Chloroplasts are the organelles where both stages of photosynthesis occur.
8
Q
What is chlorophyll?
A
Chlorophyll is the photosynthetic pigment within chloroplasts that captures light energy to initiate photosynthesis.
9
Q
What is the function of stomata in leaves?
A
Stomata are tiny pores that open to allow carbon dioxide to enter and can close to prevent water loss.
10
Q
How is water transported to photosynthesizing cells?
A
Water is absorbed by root hair cells from the soil and transported through the xylem to photosynthesizing cells.
11
Q
What is a mesophyll cell?
A
A plant cell type found in leaves that contain large amounts of chloroplasts.
12
Q
What is the function of chloroplasts?
A
A membrane-bound organelle only found in plant and photoautotroph cells that is the site of photosynthesis.
13
Q
What role does chlorophyll play in photosynthesis?
A
A chemical found in the thylakoids of chloroplasts responsible for absorbing light energy in photosynthesis.
14
Q
What is a stoma?
A
A small pore on the leaf’s surface that opens and closes to regulate gas exchange.
15
Q
What is the function of xylem in plants?
A
Vascular tissue responsible for transporting water and minerals from the roots to the leaves.
16
Q
What occurs during the light-dependent stage of photosynthesis?
A
Plants are dependent on light to split water into oxygen and hydrogen, generating high energy co-enzymes NADPH and ATP.
17
Q
Where does the light-dependent stage occur?
A
On the thylakoid membranes of chloroplasts.
18
Q
What is the purpose of the light-dependent reactions?
A
To generate high energy co-enzymes NADPH and ATP to power the second stage of photosynthesis.
19
Q
What is the light-dependent stage of photosynthesis?
A
The first stage of photosynthesis where light energy splits water molecules into oxygen and hydrogen inside the thylakoid membranes.
20
Q
What are thylakoids?
A
Flattened sac-like structures housed inside the chloroplast, made up of a chlorophyll-containing membrane enclosing a lumen, and the location of the light-dependent stage of photosynthesis.
21
Q
What is a granum?
A
A stack of thylakoids.
22
Q
What role does NADPH play in photosynthesis?
A
NADPH is a coenzyme that acts as a proton (H+) and electron carrier in photosynthesis.
23
Q
What is ATP and its function in photosynthesis?
A
Adenosine triphosphate (ATP) is a high-energy molecule that provides energy for cellular processes when broken down.
24
Q
What happens during the light-dependent stage of photosynthesis?
A
Light energy excites electrons in chlorophyll, causing water molecules to split, releasing oxygen, and generating a proton gradient to produce NADPH and ATP.
25
What enzyme catalyzes the formation of ATP in the light-dependent stage of photosynthesis?
ATP synthase catalyzes the reaction ADP + Pi -> ATP using energy from the flow of H+ down its concentration gradient.
26
What are the crucial coenzymes involved in both stages of photosynthesis?
NADPH and ATP are crucial for both the light-dependent and light-independent stages.
27
What happens to NADP+ and ADP + Pi in the light-dependent stage?
They are converted into high-energy NADPH and ATP outputs, respectively.
28
What is produced during the light-independent stage of photosynthesis?
Glucose is produced from carbon dioxide, NADPH, and ATP through a cycle of reactions occurring in the stroma of chloroplasts.
29
How do NADPH and ATP cycle between the two stages of photosynthesis?
They donate their energy in the light-independent stage and return as 'unloaded' NADP+ and ADP + Pi to the light-dependent reactions for recycling.
30
What is the light-independent stage of photosynthesis also known as?
The light-independent stage is also known as the Calvin cycle, the dark stage, or the light-independent reactions.
31
Where does the light-independent stage occur?
The light-independent stage occurs in the stroma of a chloroplast.
32
What are the inputs of the light-independent stage?
The inputs are 6CO2, 12 NADPH, and 18 ATP.
33
What are the outputs of the light-independent stage?
The outputs are glucose (C6H12O6), 6 water (6H2O), 12 NADP+, and 18 ADP + Pi.
34
What role do NADPH and ATP play in the light-independent stage?
NADPH donates hydrogen ions and electrons, while ATP provides energy for further changes to the carbon molecules.
35
What happens to carbon dioxide molecules in the Calvin cycle?
Carbon dioxide molecules enter the Calvin cycle and combine with a five-carbon molecule, forming two three-carbon molecules.
36
What is the significance of the stroma in photosynthesis?
The stroma is the fluid substance that makes up the interior of chloroplasts and is the site of the light-independent stage of photosynthesis.
37
What occurs during the rearrangement of carbon molecules in the Calvin cycle?
Carbon molecules undergo continuous rearrangements within the cycle, leading to the formation of specific three-carbon molecules.
38
What is produced from the initial splitting of CO2 in the Calvin cycle?
Oxygen molecules produced from the initial splitting of CO2 combine with hydrogen ions to produce water.
39
What is photosynthesis?
Photosynthesis is the process of turning light energy into chemical energy in the form of glucose.
40
How many distinct stages does photosynthesis occur in?
Photosynthesis occurs in two distinct stages.
41
What is Rubisco and what role does it play in photosynthesis?
Rubisco is a key enzyme in the light-independent stage of photosynthesis that facilitates the binding of carbon dioxide and initiates reactions to produce organic molecules, but it can also bind to oxygen, leading to photorespiration.
42
What are the two stages of photosynthesis?
Photosynthesis occurs in two stages: the light-dependent stage, which produces ATP, NADPH, and oxygen by splitting water molecules, and the light-independent stage (Calvin cycle), where carbon dioxide is converted into organic molecules using ATP and NADPH.
43
How does Rubisco contribute to the Calvin cycle?
Rubisco combines 3 CO2 molecules with 3 RuBP molecules to produce 6 three-carbon molecules (3-PGA), which are then converted into G3P using ATP and NADPH. One G3P exits to form glucose, while 5 G3P are recycled to regenerate RuBP.
44
Why can't plants convert CO2 directly into glucose?
Plants cannot convert CO2 directly into glucose because it would waste too much energy
45
What is carbon fixation?
The process in living organisms where inorganic carbon, typically within carbon dioxide, is converted into organic compounds such as glucose.
46
What is the difference between inorganic and organic compounds?
Inorganic compounds do not contain a carbon-hydrogen bond (e.g., carbon dioxide), while organic compounds contain a carbon-hydrogen bond (e.g., glucose).
47
What problem does Rubisco face during photosynthesis?
Rubisco sometimes binds to O2 instead of CO2, leading to photorespiration, which disrupts photosynthesis and reduces glucose production.
48
What is photorespiration?
A wasteful process in plants initiated by Rubisco that limits photosynthesis.
49
What is a substrate in the context of enzyme reactions?
The reactant of a reaction catalyzed by an enzyme.
50
What are the two primary factors influencing Rubisco's binding to CO2 or O2?
Temperature and substrate concentration.
51
How does higher CO2 concentration affect Rubisco's binding?
It favors Rubisco's binding to CO2, maximizing photosynthesis.
52
What effect does stomatal closure have on photorespiration?
It can lead to increased O2 concentration, promoting photorespiration.
53
How does temperature influence Rubisco's affinity for CO2 and O2?
At regular or low temperatures, Rubisco's affinity for CO2 is higher, but at higher temperatures, its affinity for O2 increases.
54
In what conditions is photorespiration more prevalent?
In hot and dry conditions when Rubisco has a higher affinity for O2 and stomata are closed.
55
What adaptations have certain plants evolved to mitigate photorespiration?
They enhance Rubisco's binding to CO2, thus improving photosynthesis rates.
56
What distinguishes C3, C4, and CAM plants in relation to photorespiration?
C3 plants have no features to fight photorespiration, C4 plants spatially separate carbon fixation from the Calvin cycle, and CAM plants temporally separate the two steps.
57
What percentage of plants on Earth are C3 plants?
C3 plants make up 85% of plants on Earth.
58
What type of photosynthesis do C3 plants undertake?
C3 plants undertake 'normal' photosynthesis and possess no adaptations to reduce photorespiration.
59
What is the main difference in carbon fixation between C3 and C4 plants?
C4 plants perform carbon fixation in mesophyll cells and the Calvin cycle in bundle-sheath cells, while C3 plants do both processes in the same cell.
60
What enzyme is responsible for carbon fixation in C4 plants?
PEP carboxylase is the enzyme that fixes atmospheric CO2 in C4 plants.
61
What is the first four-carbon molecule produced during carbon fixation in C4 photosynthesis?
The first four-carbon molecule produced is oxaloacetate.
62
How do CAM plants minimize photorespiration?
CAM plants separate the steps of photosynthesis over time, rather than over space like C4 plants.
63
What happens to malate in the bundle-sheath cells of C4 plants?
Malate breaks down and releases CO2, which then enters the Calvin cycle.
64
What is the role of pyruvate in C4 photosynthesis?
Pyruvate is transported back to the mesophyll cell and converted to PEP with the help of ATP.
65
What type of plant cell is primarily involved in the Calvin cycle in C4 plants?
The bundle-sheath cell is primarily involved in the Calvin cycle in C4 plants.
66
What is the primary function of mesophyll cells in C4 plants?
Mesophyll cells are responsible for the initial carbon fixation in C4 plants.
67
What do CAM plants do at night to facilitate photosynthesis?
At night, CAM plants open their stomata to bring in CO2, which is fixed into a four-carbon molecule (oxaloacetate) by the enzyme PEP carboxylase.
68
How do CAM plants store CO2 until daytime?
The CO2 is converted to malate or another organic molecule and stored inside vacuoles within the mesophyll cell until daytime.
69
What happens to the stored malate during the daytime in CAM plants?
During the daytime, malate is transported out of the vacuole and broken down to release CO2, which then enters the Calvin cycle.
70
Why do CAM plants not open their stomata during the day?
CAM plants do not open their stomata during the day to prevent water loss, making them resistant to drought conditions.
71
What is the advantage of the controlled release of CO2 in CAM plants?
The controlled release of CO2 ensures a high concentration near Rubisco, maximizing photosynthesis and minimizing photorespiration.
72
How does the ATP requirement of CAM photosynthesis compare to C3 photosynthesis?
The CAM pathway requires more ATP than C3 photosynthesis to cycle PEP.
73
In what type of environments are CAM plants commonly found?
CAM plants are prominent in very hot, dry areas like deserts.
74
Can you name some examples of CAM plants?
Examples of CAM plants include almost all cacti, pineapples, vanilla, and orchids.
75
What is required for the light-dependent stage of photosynthesis to occur?
Light is required for the light-dependent stage of photosynthesis to occur.
76
What happens to the rate of photosynthesis as light intensity increases?
The rate of photosynthesis increases as light intensity increases, up to a certain point.
77
What is the saturation point in photosynthesis?
The saturation point is when the plant is saturated with light, and the maximum rate of photosynthesis is reached.
78
What can cause the plateau in the rate of photosynthesis?
The plateau can be caused by reaching the maximum possible rate of photosynthesis or by another limiting factor.
79
What is a limiting factor in photosynthesis?
A limiting factor is one of the reactants needed for photosynthesis that is in insufficient supply compared to other factors.
80
What happens after the saturation point in terms of limiting factors?
After the saturation point, another factor such as temperature or carbon dioxide becomes the limiting factor.
81
Why is the maximum rate of photosynthesis often theoretical?
The maximum rate of photosynthesis is often theoretical due to the limited supply of inputs, making it unlikely to reach a true 'maximum'.
82
What is the saturation point in the context of enzymes?
The saturation point is the point at which a substance (e.g. an enzyme) cannot receive more of another substance (e.g. a substrate).
83
What is a limiting factor?
A limiting factor is a factor that prevents the rate of reaction from increasing.
84
What is a limiting reagent?
A limiting reagent is a reactant that prevents the rate of reaction from increasing.
85
How does light influence C3, C4, and CAM plants?
Light influences all three types in the same manner, as all still have the same light-dependent reactions.
86
How does light color affect photosynthesis?
The wavelength of light impacts photosynthesis, with the greatest effect occurring at violet or red, and the least at green, as most green light is reflected.
87
What role do temperature and pH play in photosynthesis?
Enzymes catalyze various reactions in both stages of photosynthesis, and they are likely to have similar optimal temperature and pH as they have evolved to be suited to the plant's environment.
88
What happens to the rate of photosynthesis as the temperature approaches the enzyme's optimal temperature?
The rate of photosynthesis increases due to more frequent enzyme-substrate collisions.
89
What occurs to enzymes above their optimal temperature?
The enzymes begin to denature.
90
At what pH do enzymes in the thylakoid lumen function well?
Enzymes in the thylakoid lumen can function well at a pH as low as 4.
91
How do C3, C4, and CAM plants respond to temperature and pH?
All are impacted by temperature and pH as each pathway relies on enzymes, but they have evolved to be suited to their respective environments.
92
Which type of plants are better adapted to hot and dry environments?
C4 and CAM plants are better adapted to hot and dry environments.
93
What is the role of carbon dioxide in the light-independent stage of photosynthesis?
Carbon dioxide is an input, and its concentration impacts the rate of photosynthesis.
94
How does carbon dioxide concentration affect the rate of photosynthesis?
As carbon dioxide concentration increases, the rate of photosynthesis increases up until a certain point.
95
How do C4 and CAM plants respond to reductions in carbon dioxide concentration compared to C3 plants?
C4 and CAM plants are less affected by carbon dioxide concentration reduction than C3 plants.
96
What happens to the rate of photosynthesis when stomata are closed or there is low CO2 in the atmosphere?
The rate of photosynthesis may be limited.
97
What causes the plateau on the CO2 graph in photosynthesis?
The plateau occurs when the theoretical maximum rate of photosynthesis is reached with increasing CO2, assuming light and water are unlimited and temperature is optimal, as the enzyme-catalyzed systems are fully saturated.
98
What happens to CO2 levels when other factors become limiting?
When other factors become limiting, CO2 can no longer be the limiting factor, and it could be light, water, or temperature instead.
99
How does low CO2 affect photorespiration?
Low CO2 levels lead to a higher rate of photorespiration because Rubisco has an affinity for both O2 and CO2.
100
How have C4 and CAM plants adapted to low CO2 levels?
C4 and CAM plants have evolved adaptations to counter photorespiration and expose Rubisco to greater levels of CO2, making them less susceptible to low CO2 concentration impacts.
101
What role does water play in photosynthesis?
Water influences the rate of photosynthesis as it is an input in the light-dependent stage and affects the opening and closing of stomata.
102
What happens to stomata when water levels decrease?
Decreased water levels lead to closed stomata, which decreases CO2 availability and increases O2, resulting in higher photorespiration.
103
What happens to stomata when water availability decreases?
Stomata close, leading to decreased CO2 and increased O2 concentrations, which decreases the overall rate of photosynthesis.
104
How are C4 and CAM plants adapted to water availability compared to C3 plants?
C4 and CAM plants are not affected by water availability unless it is extreme, whereas C3 plants are more susceptible to water loss and its impacts on photosynthesis rate.
105
What are competitive inhibitors?
Competitive inhibitors bind to active sites of enzymes, preventing substrate binding and catalysis.
106
What are non-competitive inhibitors?
Non-competitive inhibitors bind to allosteric sites, causing conformational changes that prevent substrate binding.
107
What is reversible inhibition?
Reversible inhibition can be overcome under certain conditions.
108
What is irreversible inhibition?
Irreversible inhibition permanently deactivates enzymes.
109
How do herbicides act as enzyme inhibitors?
Herbicides like triazines, uracils, and benzothiadiazoles inhibit enzymes in photosynthesis by binding to the D1 quinone-binding protein in the electron transport chain.
110
What effect do competitive reversible inhibitors have on reaction rates?
Their effects can be mitigated by increasing substrate concentration, potentially restoring the reaction rate.
111
What is the effect of irreversible and non-competitive reversible inhibitors on reaction rates?
Increasing substrate concentration does not overcome their effects, leading to a permanent reduction in the maximum reaction rate.
112
Are C3, C4, and CAM plants susceptible to enzyme inhibitors?
Yes, all three types of plants are susceptible to the negative impact of enzyme inhibitors.
113
How can CRISPR-Cas9 technologies improve photosynthesis in agricultural crops?
CRISPR-Cas9 can be used to edit the genome of crops to bypass photorespiration, enhance Rubisco function, improve chloroplast efficiency, and target stomata to reduce water stress.
114
What is one method to increase photosynthesis efficiency using CRISPR-Cas9?
One method is to engineer crops that mimic the function of C4 and CAM plants to bypass photorespiration.
115
What steps are involved in researching CRISPR-Cas9 applications for improving photosynthesis?
The steps include understanding the photosynthetic process of the target crop, modeling the photosynthetic pathway to identify inefficiencies, and using CRISPR-Cas9 to edit the responsible genes.
116
What role does Rubisco play in the context of CRISPR-Cas9 applications?
Rubisco's function can be directly targeted and edited to maximize photosynthesis efficiency in crops.
117
What is the significance of understanding the regulation of the photorespiration pathway?
Understanding this regulation is crucial for effectively applying CRISPR-Cas9 to improve photosynthesis in specific crop species.
118
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