Photosynthesis

Question 1

Structure of Chloroplast

Answer 1

Structure:
- Double membrane
- Thylakoids inside chloroplast -> Contains chlorophyll in thylakoid lumen
- Stroma -> Dense fluid surrounding thylakoid discs

Question 2

Equation of photosynthesis

Answer 2

Energy (From light) + Water (For light depedent) + CO2 (For Calvin Cycle) -> Oxygen (Light dependent product) + Sugar (Calvin Cycle Product)

Question 3

What is the role of light in photosynthesis?

Answer 3

1. Photosystems
   - Light energy trapped by chlorophyll pigment molecules
   - Energy is then passed into reaction center complex
   - Excites electron to higher energy state -> electron transferred to primary electron accepter
2. Photolysis of water
   - Light is involved in photolysis of water
   - Electrons produced replenishes the electron in reaction center of photosystem II

Question 4

Features of light dependent stage

Answer 4

Location: Across thylakoid membrane from stroma to thylakoid space
Reactants: H2O, NADP+, ADP
Products: O2+4H+4e-, NADPH, ATP
Photosystem II -> Photosystem I -> Enters Calvin Cycle

Question 5

Describe the electron transport chain in light dependent state

Answer 5

1. Hydrolysis of water replenishes electrons in Photosystem 2
2. Electron enters the electron transport chain -> transported by membrane proteins
3. Drives H+ protons from stroma into the thylakoid space -> Creates a proton gradient -> Protons diffuse from thylakoid space to stroma through ATP synthase
4. Electrons are used to reduce NADP+ to NADPH at end of chain -> used in kelvin cycle

Question 6

Features of light independent stage

Answer 6

Location: Stroma
Reactants: 3CO2, 6ATP, 6NADPH
Products: G3P, 6ADP, 6NADP+
- Regenerates ADP and NADP+ for light dependent stage
- Facilitated by enzymes