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: Where in the chloroplast do light-dependent reactions occur?

Answer: Thylakoid membranes. Contain photosystems and electron transport chains.

Flashcard 2: 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 3: 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 4: 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.

Flashcard 5: 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 6: What is the role of carbon dioxide in photosynthesis?

Answer: Carbon source for glucose synthesis. Fixed into organic molecules during the Calvin cycle.

Flashcard 7: Identify the three phases of the Calvin cycle.

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

Flashcard 8: What is the significance of the Z-scheme in photosynthesis?

Answer: Represents electron flow in light reactions. Shows energy changes as electrons move between photosystems.

Flashcard 9: Identify the three phases of the Calvin cycle.

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

Flashcard 10: What is the main product of the Calvin cycle?

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

Flashcard 11: Which light spectrum is least absorbed by chlorophyll a?

Answer: Green. Chlorophyll reflects green light rather than absorbing it.

Flashcard 12: Which component of the chloroplast contains chlorophyll?

Answer: Thylakoid. Membrane structures that house photosynthetic pigments.

Flashcard 13: What is the initial electron donor in photosystem II?

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

Flashcard 14: Which component of the chloroplast contains chlorophyll?

Answer: Thylakoid. Membrane structures that house photosynthetic pigments.

Flashcard 15: What molecule is produced by ATP synthase during photosynthesis?

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

Flashcard 16: In which part of the chloroplast does the Calvin cycle take place?

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

Flashcard 17: What type of light do carotenoids absorb?

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

Flashcard 18: Identify the two main stages of photosynthesis.

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

Flashcard 19: What is RuBP and its role in photosynthesis?

Answer: 5-carbon sugar involved in CO$_2$ fixation. Acceptor molecule that binds with $\text{CO}_2$ in carbon fixation.

Flashcard 20: What molecule is synthesized directly by photosystem I?

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

Flashcard 21: What is the significance of the Z-scheme in photosynthesis?

Answer: Represents electron flow in light reactions. Shows energy changes as electrons move between photosystems.

Flashcard 22: What is the main product of the Calvin cycle?

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

Flashcard 23: What process in photosynthesis generates a proton gradient across the thylakoid membrane?

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

Flashcard 24: 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.

Flashcard 25: What is the role of carbon dioxide in photosynthesis?

Answer: Carbon source for glucose synthesis. Fixed into organic molecules during the Calvin cycle.

Flashcard 26: 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 27: What does NADPH provide in the Calvin cycle?

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

Flashcard 28: What molecule is the primary electron carrier in photosynthesis?

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

Flashcard 29: Identify the compound that provides energy for carbon fixation in the Calvin cycle.

Answer: ATP. Powers carbon fixation and G3P synthesis reactions.

Flashcard 30: What molecule is produced by ATP synthase during photosynthesis?

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

Flashcard 31: What is photorespiration?

Answer: A process where oxygen is fixed instead of CO$_2$. Wasteful process where rubisco binds oxygen instead of $\text{CO}_2$.

Flashcard 32: What enzyme catalyzes the fixation of CO$_2$ in the Calvin cycle?

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

Flashcard 33: What is the energy source for ATP synthesis during photosynthesis?

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

Flashcard 34: What is the main purpose of cyclic electron flow?

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

Flashcard 35: What is the initial electron donor in photosystem II?

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

Flashcard 36: What is the energy source for ATP synthesis during photosynthesis?

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

Flashcard 37: Which gas is a byproduct of photosynthesis?

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

Flashcard 38: What does NADPH provide in the Calvin cycle?

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

Flashcard 39: Which light spectrum is least absorbed by chlorophyll a?

Answer: Green. Chlorophyll reflects green light rather than absorbing it.

Flashcard 40: What is the main purpose of cyclic electron flow?

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

Flashcard 41: What is the role of ATP in photosynthesis?

Answer: Energy source for the Calvin cycle. Provides energy for carbon fixation and G3P formation.

Flashcard 42: What molecule is synthesized directly by photosystem I?

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

Flashcard 43: Which molecule acts as the primary carrier of chemical energy in cells?

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

Flashcard 44: What is the role of ATP in photosynthesis?

Answer: Energy source for the Calvin cycle. Provides energy for carbon fixation and G3P formation.

Flashcard 45: What type of light do carotenoids absorb?

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

Flashcard 46: Identify the two main stages of photosynthesis.

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

Flashcard 47: In which organelle does photosynthesis occur?

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

Flashcard 48: Which molecule acts as the primary carrier of chemical energy in cells?

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

Flashcard 49: What is the primary function of photosystem I?

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

Flashcard 50: Which photosystem absorbs light at 680 nm?

Answer: Photosystem II. P680 reaction center splits water and begins electron flow.

Flashcard 51: What is the primary function of photosystem I?

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

Flashcard 52: What enzyme catalyzes the fixation of CO$_2$ in the Calvin cycle?

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

Flashcard 53: Which molecule is reduced to form NADPH in photosynthesis?

Answer: NADP$^+$. Electron acceptor that becomes reducing agent NADPH.

Flashcard 54: What is the role of water in the light-dependent reactions?

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

Flashcard 55: Which gas is a byproduct of photosynthesis?

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

Flashcard 56: What does the term 'photophosphorylation' refer to?

Answer: ATP synthesis using light energy. Light-driven phosphorylation of ADP to form ATP.

Flashcard 57: What molecule is the primary electron carrier in photosynthesis?

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

Flashcard 58: What is the primary pigment involved in photosynthesis?

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

Flashcard 59: In which part of the chloroplast does the Calvin cycle take place?

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

Flashcard 60: 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 61: What is the function of accessory pigments?

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

Flashcard 62: 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 63: In which organelle does photosynthesis occur?

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

Flashcard 64: What does the term 'photophosphorylation' refer to?

Answer: ATP synthesis using light energy. Light-driven phosphorylation of ADP to form ATP.

Flashcard 65: What is the source of energy that drives the light-dependent reactions?

Answer: Sunlight. Provides photons that excite chlorophyll electrons.

Flashcard 66: What adaptation allows CAM plants to minimize water loss?

Answer: Stomata open at night. Temporal separation prevents water loss during hot days.

Flashcard 67: In which part of photosynthesis is oxygen produced?

Answer: Light-dependent reactions. Water splitting in photosystem II releases oxygen gas.

Flashcard 68: Identify the compound that provides energy for carbon fixation in the Calvin cycle.

Answer: ATP. Powers carbon fixation and G3P synthesis reactions.

Flashcard 69: What is photorespiration?

Answer: A process where oxygen is fixed instead of CO$_2$. Wasteful process where rubisco binds oxygen instead of $\text{CO}_2$.

Flashcard 70: Where in the chloroplast do light-dependent reactions occur?

Answer: Thylakoid membranes. Contain photosystems and electron transport chains.

Flashcard 71: What is the role of water in the light-dependent reactions?

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

Flashcard 72: What is the function of accessory pigments?

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

Flashcard 73: In which part of photosynthesis is oxygen produced?

Answer: Light-dependent reactions. Water splitting in photosystem II releases oxygen gas.

Flashcard 74: What adaptation allows CAM plants to minimize water loss?

Answer: Stomata open at night. Temporal separation prevents water loss during hot days.

Flashcard 75: Which molecule is reduced to form NADPH in photosynthesis?

Answer: NADP$^+$. Electron acceptor that becomes reducing agent NADPH.

Flashcard 76: What is the source of energy that drives the light-dependent reactions?

Answer: Sunlight. Provides photons that excite chlorophyll electrons.

Flashcard 77: What is RuBP and its role in photosynthesis?

Answer: 5-carbon sugar involved in CO$_2$ fixation. Acceptor molecule that binds with $\text{CO}_2$ in carbon fixation.

Flashcard 78: Which photosystem absorbs light at 680 nm?

Answer: Photosystem II. P680 reaction center splits water and begins electron flow.

Flashcard 79: What process in photosynthesis generates a proton gradient across the thylakoid membrane?

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

Flashcard 80: What is the primary pigment involved in photosynthesis?

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