Plant cells obtain their energy by making their own food through the process of photosynthesis. Photosynthesis is a process by which carbon dioxide , water and light energy are utilized by plants to make energy-rich carbohydrates such as glucose. Plants store up the glucose as starch in their tissues. When plant cells needs energy, they simply take glucose molecules from their store of starch and use it in cellular respiration to produce ATP, the form of energy that the cell uses to function.
Animals on the other hand do not make their own food but ingest ready made food and break it down into its simplest units through the process of digestion. Complex carbohydrates are broken down to glucose units. Glucose is directly taken in by the animal cells where it is used in cellular respiration to produce ATP ,which fuels the cell activities.
<em> Plants mostly acquire carbon present in the atmosphere. ... Carbon is also removed by conversion of reduced carbon to organic tissues or carbonates to hard body parts.</em>
