Question

There exists a close association between the alga and the fungus within a lichen. The fungus

• A. provides protection, anchorage and absorption for the algae
• B. provides food for the alga
• C. fixes the atmospheric nitrogen for the alga
• D. releases oxygen for the alga.

Answer 1

The Correct Option is A

To understand the symbiotic relationship between the alga and the fungus within a lichen, we need to explore how each organism contributes to their mutual benefit.

Lichens are composite organisms composed of a fungus and a photosynthetic partner, usually an alga or cyanobacteria. Let's examine the roles of each partner:

1. Role of Alga: The alga in the lichen is responsible for photosynthesis, which produces carbohydrates and other organic substances. These nutrients are vital for the growth and sustenance of the fungal partner.
2. Role of Fungus: The primary role of the fungus is to:
   • Provide Protection: The fungal thallus envelops the algal cells, shielding them from environmental stressors like UV radiation and extreme temperatures.
   • Provide Anchorage: The fungus attaches the lichen to surfaces such as rocks, trees, or soil, keeping it stable.
   • Facilitate Absorption: The fungus absorbs water and mineral nutrients from the environment, supplying them to the alga.
   These functions ensure that the algae have a suitable environment and sufficient resources to carry out photosynthesis efficiently.

Based on these interactions, the correct answer is that the fungus provides protection, anchorage, and absorption for the algae. Other options mentioned do not accurately describe the role of the fungus in this partnership:

• The fungus does not provide food for the alga; it is the alga that photosynthesizes and provides nutrients.
• The fungus does not fix atmospheric nitrogen; this is the role of certain bacteria, not the fungi involved in lichens.
• The fungus does not release oxygen for the alga; instead, oxygen is a byproduct of the algae's photosynthesis.

Understanding these roles helps clarify the mutually beneficial relationship between algae and fungi in lichens.