The mass of a tree is primarily carbon. The carbon comes from<span> carbon dioxide used during photosynthesis. During photosynthesis, </span>plants<span> convert the sun's energy into chemical energy which is captured within the bonds of carbon molecules built from atmospheric carbon dioxide and water.</span>
Mitochondria are considered as the powerhouse of cell because they perform function cellular respiration process in a cell.
Cellular respiration is a process of converting the chemical energy present in nutrients into ATP which gives energy to organisms to carry out movement and physical actions.
Mitochondria performs cellular respiration process from which they can release energy present in food and nutrients.
Due to those reasons, mitochondria is called as powerhouse of cell.
