dump for dummies Flashcards
What is Photosynthesis?
The process by which autotrophic organisms convert solar energy into chemical energy stored in glucose.
What is the overall balanced equation for photosynthesis?
6CO₂ + 12H₂O + light energy → C₆H₁₂O₆ + 6O₂ + 6H₂O
What are the key requirements for photosynthesis?
- Light energy
- Chlorophyll
- Enzymes
What are the main components of chloroplast structure?
- Thylakoids
- Thylakoid Lumen
- Thylakoid Membrane
- Stroma
What is the function of thylakoids?
Site of light-dependent reactions.
What does the stroma contain?
Aqueous fluid where the Calvin Cycle occurs.
What is the role of chlorophyll a?
Main pigment, part of the reaction center.
What is the absorption spectrum?
Measures how much light is absorbed at various wavelengths.
What is the action spectrum?
Measures the effectiveness of various wavelengths in driving photosynthesis.
What wavelength does Photosystem II (PSII) absorb?
680 nm (P680)
What wavelength does Photosystem I (PSI) absorb?
700 nm (P700)
What is linear (non-cyclic) electron flow?
A sequence of steps starting from light excitation of P680 to NADPH formation.
What happens during photolysis in photosynthesis?
Water is split into protons, electrons, and oxygen.
What is chemiosmosis in photosynthesis?
Protons diffuse back through ATP synthase, synthesizing ATP.
What are the inputs of the Calvin Cycle?
- 6CO₂
- 18 ATP
- 12 NADPH
What is the main output of the Calvin Cycle?
1 Glucose (C₆H₁₂O₆)
What enzyme is involved in carbon fixation?
Rubisco
What is the role of cyclic electron flow?
Involves only PSI, builds proton gradient, produces extra ATP.
What is photorespiration?
Occurs when Rubisco binds O₂ instead of CO₂, reducing photosynthetic efficiency.
What are C4 plants adapted for?
Spatial separation of steps to minimize photorespiration.
What are CAM plants adapted for?
Temporal separation of steps to conserve water.
What factors affect photosynthesis?
- Light Intensity
- CO₂ Concentration
- Temperature
- Water Availability
What is Rubisco’s dual role?
Catalyzes carboxylation of RuBP with CO₂ but can also bind O₂.
What is the light compensation point?
The light intensity at which photosynthesis and respiration rates are equal.
What is the light saturation point?
The light intensity beyond which photosynthesis rate does not increase.
What is the main function of cyclic electron transport?
To generate ATP without producing NADPH.
What happens to photosynthesis enzymes at high temperatures?
Enzymes may become less specific, leading to increased photorespiration.
What effect do herbicides have on photosynthesis?
They can block electron transport, halting ATP and NADPH production.
What is the role of NADPH in carbon fixation?
NADPH is required to convert 3-PGA into G3P. A shortage of NADPH halts carbon fixation, affecting glucose synthesis.
What happens to ATP production if a herbicide causes the thylakoid membrane to become leaky to protons?
ATP production decreases due to reduced chemiosmotic potential, resulting in a slowdown of the Calvin Cycle.
What effect does high O₂ and low CO₂ have on 3-PGA and G3P levels in a plant?
3-PGA and G3P levels drop due to increased photorespiration, as Rubisco binds O₂ instead of CO₂.
What might be different about a plant that performs photosynthesis without releasing oxygen gas?
It likely uses an alternative electron donor such as hydrogen sulfide (H₂S) instead of water.
What is the impact of a mutation preventing malate formation in a C₄ plant?
The Calvin Cycle cannot proceed efficiently due to lack of CO₂ transport from mesophyll to bundle sheath cells.
Would you expect O₂ bubbles when shining green light on a submerged leaf?
No, because chlorophyll poorly absorbs green light, resulting in minimal activity in light-dependent reactions.
Why hasn’t evolution replaced Rubisco with a more efficient enzyme?
Rubisco evolved in an atmosphere with low O₂ and high CO₂, making its inefficiency non-problematic at that time.
Compare the stomatal activity and glucose output of a C₃ plant and a CAM plant in a hot, dry climate.
C₃ plants close stomata, reducing glucose output; CAM plants open stomata at night, maintaining glucose production.
What happens to light-dependent reactions if cold temperatures reduce membrane fluidity in thylakoids?
Electron transport slows down, reducing ATP synthesis and limiting the efficiency of the Calvin Cycle.
How would 3-PGA and G3P levels change if a chloroplast couldn’t regenerate RuBP?
3-PGA and G3P would initially accumulate but eventually plateau and decline due to halted CO₂ fixation.
Why do plants exposed to red light photosynthesize normally but not under green light?
Chlorophyll absorbs red and blue light efficiently, while green light is reflected, leading to ineffective photosynthesis.
What is the impact of a mutant plant’s ATP synthase requiring twice as many protons to make 1 ATP?
ATP yield per photon decreases, slowing ATP-dependent steps in the Calvin Cycle and reducing glucose synthesis.
How would rising atmospheric CO₂ affect C₄ and CAM plants?
C₃ plants would benefit more, while C₄ and CAM plants may lose their competitive advantage due to decreased photorespiration.
Why is it more efficient for plants to shut down the Calvin Cycle at night?
The Calvin Cycle requires ATP and NADPH from light reactions, which are not available at night, conserving resources.
What is the primary function of photosynthesis?
The primary function of photosynthesis is to convert light energy into chemical energy in the form of glucose.
Which organelle is responsible for photosynthesis in plant cells?
Chloroplasts are the organelles responsible for photosynthesis in plant cells.
True or False: Photosynthesis only occurs in leaves.
False: Photosynthesis can occur in any green part of a plant that contains chlorophyll.
Fill in the blank: The two main stages of photosynthesis are the _____ and the _____.
light-dependent reactions; light-independent reactions (Calvin cycle)
What are the reactants of the photosynthesis equation?
The reactants of photosynthesis are carbon dioxide (CO2) and water (H2O).
What is the main product of photosynthesis?
The main product of photosynthesis is glucose (C6H12O6).
Identify the pigment primarily responsible for capturing light energy in photosynthesis.
Chlorophyll is the pigment primarily responsible for capturing light energy.
Multiple Choice: Which of the following wavelengths of light is most effectively used in photosynthesis? A) Green B) Blue C) Red D) Both B and C
D) Both B and C
What role does water play in photosynthesis?
Water provides electrons and protons during the light-dependent reactions and is a source of oxygen.
True or False: Oxygen is a byproduct of the light-dependent reactions of photosynthesis.
True
What is the Calvin cycle also known as?
The Calvin cycle is also known as the light-independent reactions.
Short Answer: Name one factor that can affect the rate of photosynthesis.
Light intensity, carbon dioxide concentration, temperature, or water availability.
Multiple Choice: In which part of the chloroplast do the light-dependent reactions occur? A) Stroma B) Thylakoid membranes C) Cytoplasm D) Nucleus
B) Thylakoid membranes
Fill in the blank: The energy from light is captured by _____ and converted into ATP and NADPH.
chlorophyll
What is the significance of ATP and NADPH in photosynthesis?
ATP and NADPH provide the energy and reducing power needed for the Calvin cycle.
True or False: All plants perform photosynthesis.
False: Some plants, like parasitic plants, do not perform photosynthesis.
What is the chemical equation for photosynthesis?
6CO2 + 6H2O + light energy → C6H12O6 + 6O2
Multiple Choice: Which process occurs during the light-dependent reactions? A) Carbon fixation B) Water splitting C) Glucose synthesis D) Oxygen uptake
B) Water splitting
Short Answer: What is the role of ribulose bisphosphate (RuBP) in the Calvin cycle?
RuBP acts as a carbon dioxide acceptor, allowing carbon fixation to occur.
Fill in the blank: The enzyme _____ catalyzes the first step of the Calvin cycle.
ribulose bisphosphate carboxylase/oxygenase (RuBisCO)
True or False: The light-independent reactions can occur without light.
True
What is produced during the Calvin cycle that can be used to form glucose?
Glyceraldehyde-3-phosphate (G3P) is produced during the Calvin cycle and can be used to form glucose.
Multiple Choice: Which gas is absorbed by plants during photosynthesis? A) Oxygen B) Nitrogen C) Carbon Dioxide D) Hydrogen
C) Carbon Dioxide
What is photolysis in the context of photosynthesis?
Photolysis is the splitting of water molecules into oxygen, protons, and electrons using light energy.
Fill in the blank: The _____ are the flat, disc-like structures within chloroplasts where the light-dependent reactions take place.
thylakoids
Short Answer: How does temperature affect the rate of photosynthesis?
Higher temperatures generally increase the rate of photosynthesis up to a certain point, after which it may decrease due to enzyme denaturation.
Multiple Choice: What is the primary source of energy for photosynthesis? A) Heat B) Light C) Chemical D) Mechanical
B) Light
What is the role of stomata in photosynthesis?
Stomata are openings on the leaf surface that allow for the exchange of gases, including the intake of carbon dioxide and release of oxygen.
True or False: Photosynthesis occurs in both day and night.
False: Photosynthesis primarily occurs during the day when light is available.
Fill in the blank: The _____ is the liquid-filled space surrounding the thylakoids in chloroplasts.
stroma
What is the effect of increased carbon dioxide concentration on photosynthesis?
Increased carbon dioxide concentration typically enhances the rate of photosynthesis, up to a saturation point.
Multiple Choice: Which of the following is NOT a product of photosynthesis? A) Glucose B) Oxygen C) Water D) ATP
C) Water
Short Answer: What is the importance of photosynthesis to life on Earth?
Photosynthesis is crucial for producing oxygen and organic compounds that serve as food for living organisms.
What is the relationship between photosynthesis and cellular respiration?
Photosynthesis produces glucose and oxygen, which are used in cellular respiration to produce energy.
True or False: Only plants can perform photosynthesis.
False: Some algae and bacteria can also perform photosynthesis.
Fill in the blank: The _____ cycle is also known as the Calvin-Benson cycle.
Calvin
Multiple Choice: What is the main purpose of the light-dependent reactions? A) To produce glucose B) To convert light energy into chemical energy C) To fix carbon D) To produce oxygen
B) To convert light energy into chemical energy
Short Answer: How do chloroplasts adapt to optimize photosynthesis?
Chloroplasts have a large surface area due to thylakoid stacking, maximizing light absorption and facilitating efficient chemical reactions.
What is the role of NADPH in photosynthesis?
NADPH provides reducing power for the conversion of carbon dioxide into glucose during the Calvin cycle.
True or False: The rate of photosynthesis can be measured by the amount of oxygen produced.
True
Fill in the blank: The _____ hypothesis explains how light energy is converted to chemical energy.
Z-scheme
What is the significance of the light-harvesting complex in photosynthesis?
The light-harvesting complex captures and transfers light energy to the reaction center, enhancing the efficiency of photosynthesis.
