Lecture 33 – Photosynthesis

What is the primary source of free energy for biological systems?

Chemical reactions
Solar energy (correct)
Geothermal energy
Nuclear energy

Which process occurs during the light reactions of photosynthesis?

Oxygen is produced (correct)
Carbon dioxide is fixed
Glucose is synthesized
Starch is stored

What are the main products of the light-dependent reactions?

ATP and glucose
NADPH and O2
NADPH and ATP (correct)
FADH2 and ATP

What is the overall reaction of photosynthesis?

6 CO2 + 6 H2O → C6H12O6 + 6 O2 (A) Signup and view all the answers

What is the role of chlorophyll in photosynthesis?

To absorb light energy (B) Signup and view all the answers

Which light-absorbing complex initiates the photosynthetic electron transport chain?

Photosystem I (B) Signup and view all the answers

What is the primary function of the Hill reaction?

To evolve O2 (C) Signup and view all the answers

What happens to water molecules in Photosystem II?

They are oxidized to release electrons. (A) Signup and view all the answers

What is the final electron acceptor in the light reactions?

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Which enzyme is responsible for fixing carbon dioxide in the Calvin cycle?

Rubisco (B) Signup and view all the answers

What is the first product formed during the Calvin cycle?

3-Phosphoglycerate (B) Signup and view all the answers

Which of the following statements about Rubisco is true?

It is the most abundant protein on Earth. (C) Signup and view all the answers

What is photorespiration?

The production of ATP and NADPH. (C) Signup and view all the answers

How do C4 plants minimize the effects of photorespiration?

By concentrating CO2 around Rubisco (B) Signup and view all the answers

In which part of the chloroplast does the Calvin cycle occur?

Stroma (B) Signup and view all the answers

What is the main storage form of energy produced in plants?

Starch (C) Signup and view all the answers

Which of the following carbohydrates can be transported throughout the plant?

Sucrose (C) Signup and view all the answers

What is the role of plastocyanin in photosynthesis?

It transfers electrons from cytochrome b6f to Photosystem I. (B) Signup and view all the answers

What is the significance of the proton gradient created during the light reactions?

It drives ATP synthesis. (B) Signup and view all the answers

Which type of light has the highest energy?

Blue light (C) Signup and view all the answers

What process does the Calvin cycle primarily utilize for carbon fixation?

Carboxylation of ribulose bisphosphate (D) Signup and view all the answers

What happens during the reduction phase of the Calvin cycle?

3-Phosphoglycerate is converted to Glyceraldehyde-3-phosphate. (B) Signup and view all the answers

Which of the following statements about the light-independent reactions is true?

They use ATP and NADPH produced in the light reactions. (C) Signup and view all the answers

What is the function of the light-harvesting complex?

To absorb and transfer light energy to the reaction center (B) Signup and view all the answers

What is the primary end product of the Calvin cycle?

G3P (Glyceraldehyde-3-phosphate) (C) Signup and view all the answers

Which of the following statements about the photosynthetic electron transport chain is true?

It creates a proton gradient across the thylakoid membrane. (C) Signup and view all the answers

Which type of plants are adapted to high temperatures and low CO2 conditions?

C4 plants (B) Signup and view all the answers

What is the role of ferredoxin in photosynthesis?

It transfers electrons from Photosystem I to NADP+. (C) Signup and view all the answers

What is the significance of Melvin Calvin's experiment with Chlorella?

It identified the first stable product of carbon fixation. (B) Signup and view all the answers

What is the primary challenge faced by Rubisco in high oxygen conditions?

It favors the reaction with oxygen over carbon dioxide (photorespiration). (B) Signup and view all the answers