Photosynthesis is a redox reaction. this means that h2o is during the light reactions and co2 is during the calvin cycle. see concept

h let me think

in cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. a contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.

explanation: