Final answer:
Moving up the y-axis on a graph usually indicates an increase in the rate of photosynthesis, while moving to the right along the x-axis often signifies an increase in light intensity for graphs related to photosynthesis.
Step-by-step explanation:
As you move up the y-axis on a graph that plots the rate of photosynthesis, the rate of photosynthesis is generally increasing. Typically, an upward movement along the y-axis indicates a rise in the variable being measured—in this case, photosynthesis. As for the movement along the x-axis to the right, it would typically mean that the light intensity is increasing if the graph is plotting light intensity against the rate of photosynthesis. The greater the light intensity, the more photons are available to drive the light-dependent reactions of photosynthesis, until a saturation point is reached where the rate will no longer increase with added light.