Cellular respiration and photosynthesis are considered a cycle because the ___ of one reaction serves as the ___ for the other reaction.

Answer 1

A cycle is a series of steps that are repeated. Cellular respiration and photosynthesis are considered a cycle because the product (end material) of one reaction serves as the starting material for the other reaction. The starting material for cellular respiration is sugar and water and the products are carbon dioxide and water. Water and carbon dioxide are starting material for photosynthesis.