Final answer:
Plant cells expel excess oxygen and water while taking in carbon dioxide to maintain osmotic balance, facilitate photosynthesis, remove waste products, and allow for the continuous flow of water in plants.
Step-by-step explanation:
Plant cells expel excess oxygen and water while taking in carbon dioxide for multiple reasons. One reason is to maintain osmotic balance within the cell. By regulating the passage of gases, plants can control the amount of water lost through transpiration. Additionally, the removal of excess oxygen and water helps prevent the accumulation of waste products.
Furthermore, plants need to maintain a continuous flow of water upwards from the roots to the leaves for photosynthesis to occur. Stomata and guard cells regulate the opening and closing of pores called stomata on the leaves, allowing carbon dioxide to enter and exit the plant.
It is worth noting that both photosynthesis and cellular respiration are interconnected processes. While photosynthesis utilizes carbon dioxide and water to produce carbohydrates, cellular respiration metabolizes those carbohydrates to produce carbon dioxide and water.