AP BIOLOGY

Detailed explanation-1: -During photosynthesis, plants take in carbon dioxide (CO2) and water (H2O) from the air and soil. Within the plant cell, the water is oxidized, meaning it loses electrons, while the carbon dioxide is reduced, meaning it gains electrons. This transforms the water into oxygen and the carbon dioxide into glucose.

Detailed explanation-2: -Photosynthesis is the process through which plants convert sunlight, water, and carbon dioxide into oxygen and sugar energy. Photosynthesis continuously replenishes oxygen in the atmosphere. Phytoplankton produces roughly half of the oxygen, with the remainder produced by other green plants.

Detailed explanation-3: -In photosynthesis, solar energy is harvested and converted to chemical energy in the form of glucose using water and carbon dioxide. Oxygen is released as a byproduct.

Detailed explanation-4: -The oxygen released during photosynthesis is from the water. The plants will absorb water as well as carbon dioxide during photosynthesis. Later these water molecules are converted into oxygen and sugar. The oxygen is then released into the atmosphere whereas the sugar molecules are stored for energy.

Detailed explanation-5: -Scientists confirmed van Niel’s hypothesis that oxygen released from photosynthesis comes from water with the use of 18O, a heavy isotope, as a tracer to follow the fate of oxygen atoms during photosynthesis. The experiments showed that the O2 from plants was labeled with 18O only if water was the source of the tracer.