Question

homework - reactions of photosynthesis (partial title). an experiment was conducted in a closed system for five days. the percent of oxygen and carbon dioxide was measured daily and recorded in the table:

	% co₂	% o₂
day 2	60	40
day 3	50	50
day 4	40	60
day 5	25	75

what process most likely occurred that would explain the results?
○ glycolysis
○ photosynthesis
○ aerobic respiration
○ anaerobic respiration

Explanation:

To determine the process, analyze the gas changes: \( \% \text{CO}_2 \) decreases (from 75 to 25) and \( \% \text{O}_2 \) increases (from 25 to 75) over 5 days.

• Glycolysis: Occurs in cytoplasm, doesn’t directly change gaseous \( \text{CO}_2/\text{O}_2 \) in a closed system. Eliminate.
• Photosynthesis: Uses \( \text{CO}_2 \) and produces \( \text{O}_2 \) (equation: \( 6\text{CO}_2 + 6\text{H}_2\text{O} \xrightarrow{\text{light}} \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \)). This matches the trend ( \( \text{CO}_2 \) down, \( \text{O}_2 \) up).
• Aerobic respiration: Uses \( \text{O}_2 \) and produces \( \text{CO}_2 \) (opposite trend). Eliminate.
• Anaerobic respiration: Produces \( \text{CO}_2 \) (e.g., fermentation) but doesn’t consume \( \text{O}_2 \); trend wouldn’t show \( \text{O}_2 \) increase. Eliminate.

Answer:

B. photosynthesis