Two factors that affect photosynthesis are sunlight levels and temperature. Sunlight is essential to photosynthesis. The energy from sunlight allows chlorophyll to extract an electron from a molecule of water. When sunlight levels are too low, photosynthesis cannot occur at a fast enough rate to keep up with the plant's needs and the plant will ultimately die. Temperature is the other factor here. Photosynthesis occurs at an optimal temperature slightly above room temperature. If the temperature goes too high, photosynthesis slows down. Similarly, low temperatures also slow down photosynthesis. If photosynthesis is too low for too long, the plant will ultimately die.