Question

Write short notes on Lichen and Mycorrhiza.

Hint:

Lichens are an important ecological indicator, while mycorrhizal fungi enhance plant growth by aiding nutrient uptake, especially phosphorus.

Answer 1

Lichen:
Lichens are composite organisms that arise from the symbiotic association between a fungus and a photosynthetic partner, which is typically an alga or a cyanobacterium. This mutualistic relationship benefits both partners: the fungus provides protection and moisture to the photosynthetic partner, while the photosynthetic partner provides food (carbohydrates) to the fungus. Lichens are important indicators of environmental health, especially air quality, because they are sensitive to pollution, particularly sulfur dioxide. They can grow on a variety of surfaces, including rocks, tree bark, and soil. Types of Lichens:
1. Crustose: Lichens that form a crust-like appearance on the surface of the substrate.
2. Foliose: Leafy lichens that are loosely attached to the substrate.
3. Fruticose: Bushy lichens that have a more three-dimensional structure.
Mycorrhiza:
Mycorrhiza refers to a symbiotic association between fungi and the roots of plants. This relationship is beneficial for both organisms: the fungus assists the plant in nutrient uptake, especially phosphorus, while the plant provides the fungus with carbohydrates produced through photosynthesis. Mycorrhiza is crucial for the health and growth of many plants, as it helps in nutrient absorption and increases the plant's resistance to pathogens and environmental stress. Types of Mycorrhiza:
1. Ectomycorrhiza: The fungal hyphae form a dense layer around the root surface but do not penetrate the cells. Common in woody plants like pines and oaks. 2. Endomycorrhiza: The fungal hyphae penetrate the plant's root cells, forming structures such as arbuscules. Common in herbaceous plants and many crop species.