Organisms and Populations — BIOLOGY STD 12 Science — Question

1. Associations between fungi and plants, called mycorrhizae—The plants is benefitted by essential soil nutrients that the fungus absorbs and transfers to the plant through its roots. The fungus, in turn, derives the benefits of receiving energy-yielding carbohydrates from the plant.
2. Pollination- The flowers of a plant provide sweet, mucilaginous nectar to birds or insects in return for getting help from the birds or insets in spreading their pollen grains onto other flowers. The plant-pollinator pair often undergoes co-evolution to safeguard against the use of the nectar by other non-useful organisms.

Mutualisms differs from commensalism in that the latter provides a benefit to just one of the participating species the benefitted species being called a commensal.