Which organisms are involved in the close mutualistic relationship found in lichens?

Fungus and photosynthetic algae

The correct answer is Option (2)- Fungus and photosynthetic algae

Mutualism is a type of interaction which confers benefits on both the interacting species. Lichens represent an intimate mutualistic relationship between a fungus and photosynthesising algae or cyanobacteria. Similarly, the mycorrhizae are associations between fungi and the roots of higher plants. The fungi help the plant in the absorption of essential nutrients from the soil while the plant in turn provides the fungi with energy-yielding carbohydrates.

The mutualistic relationship in lichens is considered intimate because the fungus and the photosynthetic partners are physically connected and interdependent.

Overall, the mutualistic relationship between the fungus and photosynthetic algae or cyanobacteria in lichens is characterized by reciprocal benefits. The fungus provides a habitat and protection, while the photosynthetic partners supply organic compounds through photosynthesis. This collaboration allows lichens to thrive in diverse ecological niches and represents a fascinating example of symbiosis in nature.