AP Biology Flashcards: Photosynthesis

What this deck covers

This deck focuses on Photosynthesis, giving you a quick way to review the definitions, rules, and examples that matter most for AP Biology.

How to use these flashcards

Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: Identify the two main stages of photosynthesis.

Answer: Light-dependent reactions and Calvin cycle. Light reactions produce ATP/NADPH; Calvin cycle fixes carbon.

Flashcard 2: What enzyme catalyzes the fixation of CO$_2$ in the Calvin cycle?

Answer: Rubisco. Catalyzes the first step of carbon fixation in photosynthesis.

Flashcard 3: Which gas is a byproduct of photosynthesis?

Answer: Oxygen. Released when water molecules are split in photosystem II.

Flashcard 4: What is the overall equation for photosynthesis?

Answer: $6 \text{CO}_2 + 6 \text{H}_2\text{O} + \text{light} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6 \text{O}_2$. Converts light energy, water, and $\text{CO}_2$ into glucose and oxygen.

Flashcard 5: What is the energy source for ATP synthesis during photosynthesis?

Answer: Proton gradient. Chemiosmotic force drives ATP synthase rotation.

Flashcard 6: In which part of the chloroplast does the Calvin cycle take place?

Answer: Stroma. Fluid-filled space surrounding thylakoids where carbon fixation occurs.

Flashcard 7: What type of light do carotenoids absorb?

Answer: Blue and green light. Accessory pigments that broaden photosynthetic light absorption.

Flashcard 8: What molecule is synthesized directly by photosystem I?

Answer: NADPH. Electron acceptor reduced at the end of photosystem I.

Flashcard 9: What is the function of accessory pigments?

Answer: Expand the range of light absorption. Capture wavelengths chlorophyll cannot absorb efficiently.

Flashcard 10: What is the main purpose of cyclic electron flow?

Answer: Produce ATP without NADPH. Balances ATP/NADPH ratio for optimal Calvin cycle function.

Flashcard 11: What is the source of energy that drives the light-dependent reactions?

Answer: Sunlight. Provides photons that excite chlorophyll electrons.

Flashcard 12: What process in photosynthesis generates a proton gradient across the thylakoid membrane?

Answer: Electron transport chain. Creates proton concentration difference for ATP synthesis.

Flashcard 13: What is the primary function of photosystem I?

Answer: Produce NADPH. Reduces $\text{NADP}^+$ to NADPH using light energy.

Flashcard 14: What enzyme catalyzes the fixation of CO$_2$ in the Calvin cycle?

Answer: Rubisco. Catalyzes the first step of carbon fixation in photosynthesis.

Flashcard 15: What is the primary pigment involved in photosynthesis?

Answer: Chlorophyll. Green pigment that absorbs light energy for photosynthesis.

Flashcard 16: What is the initial electron donor in photosystem II?

Answer: Water (H$_2$O). Split to provide electrons and release oxygen gas.

Flashcard 17: What molecule is produced by ATP synthase during photosynthesis?

Answer: ATP. Energy currency synthesized via chemiosmosis in thylakoids.

Flashcard 18: What is the main product of the Calvin cycle?

Answer: Glucose. Six-carbon sugar formed from $\text{CO}_2$ fixation and reduction.

Flashcard 19: Identify the three phases of the Calvin cycle.

Answer: Carbon fixation, reduction, regeneration. Sequential steps that convert $\text{CO}_2$ into glucose precursors.

Flashcard 20: What is the overall equation for photosynthesis?

Answer: $6 \text{CO}_2 + 6 \text{H}_2\text{O} + \text{light} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6 \text{O}_2$. Converts light energy, water, and $\text{CO}_2$ into glucose and oxygen.

Flashcard 21: Which gas is a byproduct of photosynthesis?

Answer: Oxygen. Released when water molecules are split in photosystem II.

Flashcard 22: Which molecule acts as the primary carrier of chemical energy in cells?

Answer: ATP. Stores and transfers energy in phosphate bonds.

Flashcard 23: What is the main difference between C3 and C4 plants?

Answer: C4 plants fix CO$_2$ into a 4-carbon compound. Spatial separation reduces photorespiration in hot climates.

Flashcard 24: What is the role of water in the light-dependent reactions?

Answer: Electron donor. Provides electrons when split by photosystem II.

Flashcard 25: What does NADPH provide in the Calvin cycle?

Answer: Reducing power. Donates electrons for carbon dioxide reduction reactions.

Flashcard 26: What molecule is the primary electron carrier in photosynthesis?

Answer: NADP$^+$. Accepts electrons to form NADPH for the Calvin cycle.

Flashcard 27: Name the 3-carbon molecule produced in the Calvin cycle.

Answer: Glyceraldehyde-3-phosphate (G3P). Precursor molecule used to synthesize glucose and regenerate RuBP.

Flashcard 28: In which organelle does photosynthesis occur?

Answer: Chloroplast. Contains thylakoids and stroma where photosynthetic reactions occur.

Flashcard 29: Which component of the chloroplast contains chlorophyll?

Answer: Thylakoid. Membrane structures that house photosynthetic pigments.

Flashcard 30: Which molecule is regenerated in the Calvin cycle to accept CO$_2$?

Answer: Ribulose bisphosphate (RuBP). Five-carbon acceptor molecule for $\text{CO}_2$ in carbon fixation.