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What is photosynthesis?
Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy stored in glucose.
What are the reactants of photosynthesis?
Carbon dioxide (CO₂), water (H₂O), and sunlight.
What are the products of photosynthesis?
Glucose (C₆H₁₂O₆) and oxygen (O₂).
What is the overall chemical equation for photosynthesis?
: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂.
Why is photosynthesis ecologically important?
It produces oxygen for respiration, provides energy for the food chain, and helps remove CO₂ from the atmosphere.
What is the main pigment responsible for photosynthesis?
Chlorophyll, found in chloroplasts.
Where in the cell does photosynthesis take place?
In the chloroplasts of plant cells.
Where do the light-dependent reactions occur?
In the thylakoid membranes of the chloroplast.
What are the main products of light-dependent reactions?
ATP, NADPH, and oxygen.
What is the role of water in the light-dependent reactions?
It is split into oxygen, protons, and electrons to replace those lost by chlorophyll.
What is the purpose of ATP and NADPH?
They store energy and transfer it to the light-independent reactions (Calvin Cycle).
Where does the Calvin Cycle occur?
In the stroma of the chloroplast.
What does the Calvin Cycle use to make glucose?
ATP, NADPH, and CO₂.
What is the first step of the Calvin Cycle?
Carbon fixation – CO₂ is captured by RuBP (ribulose bisphosphate) using the enzyme Rubisco.
What happens during the reduction phase of the Calvin Cycle?
ATP and NADPH convert 3-PGA into G3P, a precursor to glucose.
What happens during the regeneration phase?
Some G3P molecules regenerate RuBP to continue the cycle.
What are the main factors that affect photosynthesis?
Light intensity, CO₂ concentration, temperature, and water availability.
How does light intensity affect photosynthesis?
Higher light intensity increases the rate until a saturation point is reached
How does CO₂ concentration affect photosynthesis?
More CO₂ increases the rate until a maximum level is reached.
How does temperature affect photosynthesis?
Enzymes work best at optimal temperatures; too high or too low slows the rate.
How does water availability affect photosynthesis?
A lack of water can slow or stop photosynthesis since water is a reactant.
What is the role of stomata in photosynthesis?
They allow gas exchange (CO₂ in, O₂ out) but also control water loss.
What happens to glucose produced in photosynthesis?
It is used for energy (cellular respiration) or stored as starch.
What is photorespiration, and why is it inefficient?
It occurs when Rubisco binds to O₂ instead of CO₂, wasting energy and reducing efficiency.
