Biology Flashcards: Explain Light To Chemical Energy

What this deck covers

This deck focuses on Explain Light To Chemical Energy, giving you a quick way to review the definitions, rules, and examples that matter most for Biology.

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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: What is the term for ATP production powered by light-driven electron transport in chloroplasts?

Answer: Photophosphorylation. ATP synthesis driven by light energy through electron transport.

Flashcard 2: What is the role of accessory pigments such as carotenoids in photosynthesis?

Answer: Absorb additional wavelengths and transfer energy to chlorophyll. Expand the range of light wavelengths captured for photosynthesis.

Flashcard 3: What gas is released as a byproduct when water is split in photosynthesis?

Answer: $O_2$. Oxygen is released when water is split to provide electrons.

Flashcard 4: Which photosystem is used in cyclic electron flow?

Answer: Photosystem I. Only PSI participates in the cyclic pathway.

Flashcard 5: What organelle converts light energy into chemical energy during photosynthesis?

Answer: Chloroplast. Contains thylakoids where light reactions occur and stroma for the Calvin cycle.

Flashcard 6: Identify the correct location for Rubisco activity: thylakoid lumen, thylakoid membrane, or stroma.

Answer: Stroma. Calvin cycle enzymes operate in the chloroplast's fluid matrix.

Flashcard 7: Identify the direct source of the $O_2$ released in photosynthesis: $CO_2$ or $H_2O$?

Answer: $H_2O$. Oxygen atoms in released $O_2$ come from split water molecules.

Flashcard 8: Choose the correct pairing: PSI reaction center is $P680$ or $P700$?

Answer: PSI is $P700$. PSI contains $P700$ chlorophyll reaction center.

Flashcard 9: Choose the correct pairing: PSII reaction center is $P680$ or $P700$?

Answer: PSII is $P680$. PSII contains $P680$ chlorophyll reaction center.

Flashcard 10: What is the role of accessory pigments such as carotenoids in photosynthesis?

Answer: Absorb additional wavelengths and transfer energy to chlorophyll. Expand the range of light wavelengths captured for photosynthesis.

Flashcard 11: What is the name for chlorophyll and accessory pigments that capture light in a photosystem?

Answer: Light-harvesting complex (antenna complex). Network of pigments that collect and funnel light energy.

Flashcard 12: What is the immediate energy conversion when chlorophyll absorbs a photon?

Answer: Light energy excites an electron to a higher energy level. Photon energy elevates electrons to higher energy states.

Flashcard 13: Which stage of photosynthesis can proceed without light if ATP and NADPH are available?

Answer: Calvin cycle. Can operate independently if energy carriers are available.

Flashcard 14: Which stage of photosynthesis directly requires photons to proceed?

Answer: Light-dependent reactions. Light is directly needed to drive photosystem reactions.

Flashcard 15: What is the balanced overall equation for oxygenic photosynthesis?

Answer: $6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$. Overall reaction showing $CO_2$ and water converting to glucose and oxygen.

Flashcard 16: What is the main chemical form in which light energy is stored after photosynthesis?

Answer: Chemical energy in sugars (such as glucose). Light energy is converted into stable chemical bonds in carbohydrates.

Flashcard 17: What is the immediate 3-carbon product formed after $CO_2$ fixation and splitting of the 6-carbon intermediate?

Answer: 3-PGA (3-phosphoglycerate). First stable product formed after $CO_2$ combines with RuBP.

Flashcard 18: What is the term for incorporating inorganic $CO_2$ into an organic molecule?

Answer: Carbon fixation. Conversion of inorganic carbon into organic molecules.

Flashcard 19: Which molecule provides the energy input to phosphorylate intermediates in the Calvin cycle?

Answer: ATP. Powers the phosphorylation reactions in the Calvin cycle.

Flashcard 20: Which molecule provides the reducing power to convert 3-PGA into G3P?

Answer: NADPH. Provides electrons and hydrogen for reducing carbon compounds.

Flashcard 21: What 3-carbon molecule is the direct carbohydrate product that exits the Calvin cycle?

Answer: G3P (glyceraldehyde-3-phosphate). Three-carbon sugar that can be used to make glucose.

Flashcard 22: What 5-carbon molecule does Rubisco attach $CO_2$ to at the start of the Calvin cycle?

Answer: RuBP (ribulose-1,5-bisphosphate). Five-carbon acceptor molecule for $CO_2$ in the Calvin cycle.

Flashcard 23: What is the main carbon-fixing enzyme of the Calvin cycle?

Answer: Rubisco. Catalyzes the attachment of $CO_2$ to RuBP in carbon fixation.

Flashcard 24: What is cyclic electron flow primarily used to produce in chloroplasts?

Answer: ATP (without NADPH production). Generates extra ATP when more is needed than NADPH.

Flashcard 25: What is the name of the pathway describing electron flow from PSII to PSI to NADP$^+$?

Answer: Noncyclic (linear) electron flow. Standard pathway from water to NADP$^+$ producing ATP and NADPH.

Flashcard 26: What are the three direct products of water splitting (photolysis) in chloroplasts?

Answer: Electrons, $H^+$, and $O_2$. Water splitting provides electrons, protons, and releases oxygen gas.

Flashcard 27: What are the two main energy-rich products of the light-dependent reactions?

Answer: ATP and NADPH. Energy carriers that power $CO_2$ fixation in the Calvin cycle.

Flashcard 28: What reduced electron carrier is produced when NADP$^+$ gains electrons and $H^+$?

Answer: NADPH. Carries electrons and protons to power Calvin cycle reactions.

Flashcard 29: What molecule is the final electron acceptor in the light-dependent reactions?

Answer: NADP$^+$. Accepts electrons from PSI to become reduced to NADPH.

Flashcard 30: In which direction do protons flow through ATP synthase in chloroplasts?

Answer: From thylakoid lumen to stroma. Protons flow down their gradient through ATP synthase channels.