3. Which factor least influences the rate of
   photosynthesis?
   (1) atmospheric concentration of carbon dioxide
   (2) time of day
   (3) number of chloroplasts
   (4) concentration of nitrogen in the air

The concentration of nitrogen in the air is actually not a direct factor affecting the rate of photosynthesis. While plants do need nitrogen for growth, particularly for building proteins and nucleic acids, it does not influence the photosynthetic process itself like carbon dioxide levels, light availability, or chloroplast numbers do.

In contrast, the atmospheric concentration of carbon dioxide is essential for photosynthesis, as it’s one of the raw materials that plants convert into glucose and oxygen. The time of day impacts light availability for the process, and chloroplasts are necessary organelles where photosynthesis occurs.