Answer:
It happens because of the process of respiration in which plants take in oxygen and give out carbon dioxide. As soon as the sun rises another process called photosynthesis starts, in which carbon dioxide is taken in and oxygen is given out
Step-by-step explanation:
process: respiration, and photosynthesis
when: as soon as sun rises
why: Plants and animals, in turn, convert the food compounds by combining it with oxygen to release energy for growth and other life activities