DENDROLOGY

Detailed explanation-1: -The leftovers from making the plant food is another gas called oxygen. This oxygen is released from the leaves into the air. Take a look at the picture below to see this system in action. This leftover oxygen is really important because humans and other animals need this oxygen to live which we breathe in from the air.

Detailed explanation-2: -Plants take in CO2 during photosynthesis and give out oxygen into the atmosphere, while animals take in oxygen and breathe out carbon dioxide during respiration. In this way, plants and animals help each other in the exchange of gases in the atmosphere.

Detailed explanation-3: -Water has dissolved oxygen which is used by the aquatic life for respiration. Oxygen dissolves into water from two sources. The atmosphere and from plants in water. The primary source of oxygen through photosynthesis of submerged plant.

Detailed explanation-4: -This process produces oxygen as a by-product and this by-product of green life is thought to have given rise to the current atmospheric oxygen levels of around 20%. Simplified, we breathe in oxygen and carbon dioxide out, and plants do the opposite.