During cellular respiration, a glucose molecule is gradually broken down into carbon dioxide and water. Along the way, some ATP is produced directly in the reactions that transform glucose. Much more ATP, however, is produced later in a process called oxidative phosphorylation. Glucose is produced by plants through photosynthesis. In this process, the plant uses light energy from the Sun to convert carbon dioxide and water into glucose and oxygen. Algae and certain bacteria and other unicellular organisms also produce glucose through photosynthesis.
DNA replication is important because without it, cell division could not occur. With DNA replication, the set of DNA of a cell can be duplicated and then each cell that results from division can have its own entire set of DNA, and cell division can theoretically continue indefinitely.
