Ontario Grade 9 Science Practice Exam 2025 – Complete Study Resource

Photosynthesis is the process by which plants, along with some algae and bacteria, convert light energy into chemical energy in the form of glucose. During this process, chlorophyll, the green pigment present in plant cells, captures sunlight and uses that energy to transform carbon dioxide from the air and water from the soil into glucose and oxygen. This not only provides essential energy for the plant itself but also produces oxygen as a byproduct, which is vital for the survival of most living organisms on Earth.

The importance of photosynthesis extends beyond the individual plant; it plays a crucial role in the Earth's ecosystem by serving as the foundational source of energy for nearly all life forms. Through photosynthesis, plants serve as primary producers in food chains, contributing to the transfer of energy to herbivores and subsequently to carnivores. Thus, understanding photosynthesis is fundamental to grasping concepts related to energy flow in ecosystems, making the correct answer the process of converting light energy into chemical energy.