P1 - Light-Dependent Reactions Flashcards
What portion of the plant performs photosynthesis?
The leaves
What tissue in the leaves performs photosynthesis?
The mesophyll
What organelle is responsible for photosynthesis?
The chloroplast
How does carbon dioxide enter the leaf?
Through the stomata
What are the main structures inside a chloroplast?
Thylakoids (stacked into grana) and stroma
Where is chlorophyll located in the chloroplast?
Embedded in the thylakoid membrane
What is the purpose of photosynthesis?
To convert light energy into chemical potential energy and oxygen
What are the two stages of photosynthesis?
Light-dependent reactions and light-independent reactions
Where do light-dependent reactions occur?
In the thylakoid membrane
Where do light-independent reactions occur?
In the stroma
What are the three main energy-containing molecules formed during photosynthesis?
ATP, NADPH, and glucose
What is light?
A form of electromagnetic radiation (EMR)
What are photons?
Packets of light energy at specific wavelengths
How does wavelength affect energy?
Shorter wavelengths have higher energy; longer wavelengths have lower energy
Which has more energy: red light or blue light?
Blue light
Why do leaves appear green?
They reflect green light and absorb other colors
What is the main pigment in plants?
Chlorophyll
What are the two types of chlorophyll, and how do they function?
- Chlorophyll a (blue-green): Main pigment that transfers energy to photosynthesis reactions
- Chlorophyll b (yellow-green): Passes energy to chlorophyll a
What is the purpose of light-dependent reactions?
To capture solar energy and convert it into ATP and NADPH
What are the three stages of light-dependent reactions?
- Capturing solar energy
- Electron transport chain & ATP creation
- NADPH creation
What is the role of Photosystem II?
It absorbs light energy and excites electrons
What happens during photolysis?
Water molecules split into oxygen, protons (H⁺), and electrons
What happens to excited electrons from Photosystem II?
They enter the electron transport chain (ETC)
What does the ETC do?
Passes electrons to Photosystem I while using their energy to pump H⁺ into the thylakoid space
What process creates ATP?
Chemiosmosis – H⁺ ions flow through ATP synthase, generating ATP
What happens at Photosystem I?
Electrons absorb more light energy and get excited again
What is the final electron acceptor in the light-dependent reactions?
NADP⁺, which is reduced to NADPH
Why is NADPH important?
It carries high-energy electrons to the Calvin Cycle (light-independent reactions)
