DENDROLOGY

Detailed explanation-1: -Through a process called photosynthesis, leaves pull in carbon dioxide and water and use the energy of the sun to convert this into chemical compounds such as sugars that feed the tree. But as a by-product of that chemical reaction oxygen is produced and released by the tree.

Detailed explanation-2: -While trees use carbon dioxide to make their own food, they actually need oxygen (much like humans do) to process that food into energy. In order to use stored starch for growth, trees must convert the sugars back into energy through a process called respiration. Respiration requires oxygen.

Detailed explanation-3: -Plants use photosynthesis to capture carbon dioxide and then release half of it into the atmosphere through respiration. Plants also release oxygen into the atmosphere through photosynthesis.

Detailed explanation-4: -Trees release oxygen when they use energy from sunlight to make glucose from carbon dioxide and water. Like all plants, trees also use oxygen when they split glucose back down to release energy to power their metabolisms.