The by-product in plant photosynthesis is oxygen.
During photosynthesis, plants use sunlight to convert carbon dioxide and water into glucose (a type of sugar) and oxygen. This process occurs in the chloroplasts of plant cells, where the pigment chlorophyll captures sunlight and converts it into energy.
The carbon dioxide is taken in through tiny pores in the leaves called stomata, and the water is absorbed by the roots and transported to the leaves through specialized tubes called xylem. With the help of the energy from the sunlight, the carbon dioxide and water are broken down into glucose and oxygen.
The glucose is used as a source of energy for the plant, while the oxygen is released into the atmosphere as a by-product. This oxygen is essential for the survival of many organisms, including humans, as we breathe in oxygen to survive. Therefore, plants play a critical role in maintaining the balance of oxygen and carbon dioxide in the Earth's atmosphere through photosynthesis.