Question

explain how photosynthesis and cellular respiration act as a cycle.
summarize the process of aerobic cellular respiration.

Explanation:

First Question (Explain how photosynthesis and cellular respiration act as a cycle)

Photosynthesis (by plants/algae) uses \( \ce{CO_2} \), \( \ce{H_2O} \), and light energy to produce glucose (\( \ce{C_6H_{12}O_6} \)) and \( \ce{O_2} \) (formula: \( 6\ce{CO_2} + 6\ce{H_2O} \xrightarrow[\text{Chlorophyll}]{\text{Light}} \ce{C_6H_{12}O_6} + 6\ce{O_2} \)). Cellular respiration (in cells) breaks glucose using \( \ce{O_2} \) to release energy, producing \( \ce{CO_2} \), \( \ce{H_2O} \), and ATP (formula: \( \ce{C_6H_{12}O_6} + 6\ce{O_2}
ightarrow 6\ce{CO_2} + 6\ce{H_2O} + \text{ATP} \)). The \( \ce{O_2} \) from photosynthesis is used in respiration, and the \( \ce{CO_2} \) from respiration is used in photosynthesis, creating a cycle.

Aerobic cellular respiration occurs in three main stages: 1. Glycolysis: Glucose (6 - carbon) is broken into two pyruvate (3 - carbon) molecules in the cytoplasm, producing a small amount of ATP and \( \ce{NADH} \). 2. Krebs Cycle (Citric Acid Cycle): Pyruvate is transported to the mitochondria, converted to acetyl - CoA, and enters a cycle that produces \( \ce{NADH} \), \( \ce{FADH_2} \), ATP, and \( \ce{CO_2} \). 3. Electron Transport Chain (ETC): \( \ce{NADH} \) and \( \ce{FADH_2} \) from previous stages donate electrons to a chain of proteins in the inner mitochondrial membrane. Oxygen acts as the final electron acceptor, combining with \( \ce{H^+} \) to form water. The energy from electron transfer is used to pump \( \ce{H^+} \), creating a gradient that drives ATP synthesis (chemiosmosis), producing a large amount of ATP. Overall, glucose is oxidized to \( \ce{CO_2} \), and oxygen is reduced to water, with a net gain of around 30 - 32 ATP per glucose molecule.

Answer:

Photosynthesis produces glucose and oxygen (using carbon dioxide, water, and light). Cellular respiration uses glucose and oxygen to produce energy, carbon dioxide, and water. The oxygen from photosynthesis fuels respiration, and the carbon dioxide from respiration fuels photosynthesis, forming a cycle.

Second Question (Summarize the process of aerobic cellular respiration)