Which of the following actions would most likely slow the respiration rate?

• A. Increasing surrounding temperatures
• B. Using more water
• C. Lowering surrounding temperatures
• D. Exposing to direct sunlight

Answer: (C)

Lowering surrounding temperatures slows the respiration rate because cellular respiration depends on enzyme activity, which decreases as temperature drops. When it’s cooler, the chemical steps of glycolysis, the citric acid cycle, and oxidative phosphorylation happen more slowly, reducing ATP production and CO2 release. The other options tend to increase or not directly slow metabolic activity: higher temperatures generally speed up respiration, direct sunlight can raise temperature or stress the plant, and simply having more water doesn’t directly slow the enzymatic processes of respiration.