B. Cellular Respiration

Front: What is the equation for cellular respiration?
Back: C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O + energy.

Front: What happens to a substrate when NAD removes hydrogen during cellular respiration?
Back: The substrate is oxidized as it loses electrons (H⁺ + e⁻).

Front: What is the result of glucose oxidation in cellular respiration?
Back: Glucose is oxidized to CO₂ and H₂O, producing ATP.

Front: What role does NAD⁺ play in oxidation reactions?
Back: It accepts 2 electrons and 1 H⁺ to form NADH.

C. Electron Transport Chain

Front: What do photosynthesis and respiration share regarding the electron transport chain?
Back: Both involve membrane-bound carriers passing electrons.

Front: What happens to electrons in the electron transport chain?
Back: High-energy electrons enter, low-energy electrons leave, releasing energy.

Front: What is the main function of redox reactions in the chain?
Back: Energy is released for ATP production at each electron transfer.

D. ATP Production

Front: What is ATP synthesis linked to?
Back: The electron transport system.

Front: Who proposed the chemiosmotic theory of ATP production?
Back: Peter Mitchell (Nobel Prize, 1978).

Front: How are electrochemical gradients created for ATP production?
Back: H⁺ ions collect on one side of the membrane, pumped by proteins.

Front: What role does ATP synthase play?
Back: It allows H⁺ to flow down the gradient, coupling this flow to ATP formation.

Front: How is the H⁺ gradient formed in photosynthesis?
Back: Energized electrons pump H⁺ across the thylakoid membrane; ATP forms as H⁺ flows through ATP synthase.

Front: How does cellular respiration create a proton gradient?
Back: Glucose breakdown provides energy to pump H⁺ across the mitochondrial membrane.

7.1 Photosynthetic Organisms

Front: What does photosynthesis convert?
Back: Solar energy into chemical energy of carbohydrates.

Front: Define autotrophs and heterotrophs.
Back: Autotrophs produce their own food; heterotrophs consume pre-formed organic molecules.

Front: How does oxygen benefit life and the environment?
Back: Oxygen is used for respiration and forms the ozone shield.

7.2 The Process of Photosynthesis

Front: What is the net equation of photosynthesis?
Back: 6 CO₂ + 6 H₂O → C₆H₁₂O₆ + 6 O₂.

Front: What is oxidized and reduced in photosynthesis?
Back: Water is oxidized; CO₂ is reduced.

Front: What molecule carries electrons in photosynthesis?
Back: NADP⁺ carries electrons, forming NADPH.

Front: How is oxygen released in photosynthesis?
Back: It comes from the splitting of water, not CO₂.

Two Sets of Reactions

Front: What are the two types of photosynthesis reactions?
Back: Light reactions (energy-capturing) and Calvin cycle reactions (synthetic).

Front: What happens in light reactions?
Back: Chlorophyll absorbs solar energy, energizing electrons for ATP and NADPH production.

Front: Where do Calvin cycle reactions occur, and what do they do?
Back: In the stroma; they use ATP and NADPH to reduce CO₂.

7.3 Plants as Solar Energy Converters

Front: Why do leaves appear green?
Back: Chlorophyll absorbs violet, blue, and red light but reflects green.

Front: What happens to pigments in the fall?
Back: Chlorophyll breaks down, revealing carotenoids (yellow-orange).

Front: What is a photosystem?
Back: A unit of pigments and electron acceptors that generates high-energy electrons.

Electron Flow in Light Reactions

Front: What are the two photosystems in light reactions?
Back: Photosystem I (PSI) and Photosystem II (PSII).

Front: How does PSII contribute to oxygen production?
Back: PSII splits water, releasing O₂, H⁺, and electrons.

Front: What is the role of the electron transport chain in photosynthesis?
Back: It pumps H⁺ ions, creating a gradient for ATP production.

Front: How is NADPH formed?
Back: PSI absorbs energy, passing electrons to NADP⁺, forming NADPH.

7.4 Plants as Carbon Dioxide Fixers

Front: What is the Calvin cycle?
Back: A series of reactions producing carbohydrates, including CO₂ fixation, reduction, and RuBP regeneration.

Front: What enzyme is crucial for CO₂ fixation?
Back: RuBP carboxylase (rubisco).

Front: What is the role of G3P in plants?
Back: It forms glucose, sucrose, starch, cellulose, fatty acids, and amino acids.

7.5 Other Types of Photosynthesis

C4 Photosynthesis

Front: How does C4 photosynthesis differ from C3?
Back: C4 plants fix CO₂ in mesophyll cells using PEPCase, forming oxaloacetate.

Front: Why are C4 plants more efficient in hot climates?
Back: They avoid photorespiration and maintain a higher photosynthetic rate.

CAM Photosynthesis

Front: How do CAM plants adapt to arid conditions?
Back: They fix CO₂ at night, storing it as C4 molecules, and use it during the day with closed stomata.

Front: Why is photosynthesis slower in CAM plants?
Back: Limited CO₂ is fixed at night, but they conserve water efficiently.

E. Tropical Rainforest Destruction and Global Warming

Front: What causes climate change?
Back: Increased atmospheric CO₂ from burning fossil fuels and deforestation.

Front: Why are tropical rainforests critical to Earth's system?
Back: They absorb CO₂, support photosynthesis, and regulate climate.

Front: What are the effects of rainforest destruction?
Back: It adds CO₂ to the atmosphere and eliminates trees that absorb CO₂.