Energy Transformations
What is the original source of energy for almost all life on Earth?
The sun
Which organelle is responsible for photosynthesis?
The chloroplast
Where do the light-dependent reactions occur?
In the thylakoid membranes of the chloroplast.
Where do the light-independent reactions take place?
In the stroma of the chloroplast.
What is the main function of ATP in photosynthesis?
ATP provides the chemical energy needed to power reactions in the Calvin Cycle.
During photosynthesis, what form of energy is sunlight converted into?
Chemical energy (stored in glucose)
What pigment inside the chloroplast absorbs sunlight?
Chlorophyll, specifically the green pigment.
What are the reactants of the light-dependent reactions?
Water and light energy.
What reactants/inputs are required for the Calvin Cycle?
CO2, ATP, and NADPH.
Why is oxygen released during the light-dependent reactions?
It is produced as a byproduct when water molecules are split during photolysis.
What is the chemical equation for Cellular Respiration?
C6H12O6 +6O2 → 6CO2+ 6H2O + ATP
What are thylakoids, and how are they arranged?
They are disc-shaped membranes, stacked into grana inside the chloroplast.
What are the products of the light-dependent reactions?
Oxygen, ATP, and NADPH.
What are the products of the Calvin Cycle?
Glucose, ADP, and NADPH. NADPH is Nicotinamide Adenine Dinucleotide Phosphate that carries hydrogen. (which returns to the thylakoid)
Why is photosynthesis considered a type of energy transformation?
Because it converts light energy from the Sun into stored chemical energy in glucose molecules.
What is the chemical equation for photosynthesis?
6CO2 + 6H2O + light energy → CO6H12O6 +6O2
What is the main function of the thylakoids, and what do they produce?
They are the site of the light-dependent reactions, producing ATP, NADPH, and oxygen.
How does sunlight affect the electrons in chlorophyll during the light-dependent reactions?
Electrons become energized and move through the ETC, forming ATP and NADPH.
How is carbon dioxide used in the Calvin Cycle?
Carbon dioxide is "fixed" into organic molecules, which are rearranged to form glucose through a process called carbon fixation.
What would happen to photosynthesis if there were no sunlight?
The light-dependent reactions would stop, so no ATP or NADPH would form, stopping glucose production.
How are photosynthesis and cellular respiration related to each other?
The products of photosynthesis are the reactants of cellular respiration, and vice versa.
What is the stroma, and what process occurs there?
The fluid-filled space around the thylakoids; it's where the light-independent reactions (Calvin Cycle) take place.
What happens during photolysis in the light reaction? Hint: Photolysis is a key step in light-dependent reactions!
Water molecules split which releases oxygen, hydrogen ions, and electrons.
What is the main purpose of the Calvin Cycle?
To use energy from ATP and NADPH to build glucose molecules.
How do the light-dependent and light-independent reactions work together?
The light reactions produce ATP and NADPH that fuel the Calvin Cycle to make glucose.