Final answer:
The photosynthetic partner in lichens benefits from protection against excessive light by the fungal partner, which aids in safeguarding against photo-oxidative stress, allowing for optimal growth and photosynthesis.
Step-by-step explanation:
Protection from light benefits the photosynthetic partner in lichens by providing an optimal environment for its growth and survival. While the photosynthetic organisms, such as algae or cyanobacteria, are capable of capturing sunlight to perform photosynthesis, excessive light can be harmful. The fungal partner in lichens offers protection from dryness and excessive light by wrapping its hyphae around the photosynthetic cells. This protection enables the photosynthetic partner to produce carbohydrates effectively without the risk of light-induced damage, which could lead to photo-oxidative stress and ultimately impede the growth and function of the photosynthetic cells.