Question

All the following interaction are mutualism, except
(a) Association of algae and fungi
(b) Association of fungi and roots of higher plants
(c ) Plant and animal for pollination
(d) Association of cattle egret and grazing cattle

Answer 1

Hint: In an ecosystem, organisms live together and interact, influencing each other’s life directly or indirectly. Scientists broadly categorize these interactions into positive and negative interactions, based on the nature of the effect on each of these interacting organisms.

Complete answer:
In a positive interaction, either both or at least one of the interacting organisms gets the benefit and neither of them is harmed. Mutualism is one such positive interaction.
Mutualism is a symbiotic relationship where members of two different species interact and both get to benefit from this association. Examples include Lichens which is a close association between fungus and algae. Association of fungi and roots of higher plants also forms a mutualistic relationship, Mycorrhizae. In pollination also, an animal helps a plant in dispersing pollens and in turn gets helped with a food source.
Commensalism is another positive interaction which literally means ‘at table together.’ In this association, one gets benefits while the other organism neither benefits nor suffers. Here, usually, the host species provides a home and/or transportation for the other species.
Like, in the association of cattle egret and grazing cattle where grazing cattle is the host, helping egret to find food. The cattle while grazing, stir up the vegetation. This causes the insects to flush out of the grasses and gets caught by cattle egrets. So, an egret roaming around a grazing cattle is benefitted in terms of food that are usually difficult to find while the cattle is neither benefit nor harmed.
So, the correct answer is ‘Association of cattle egret and grazing cattle.’

Note:
- In a negative interaction, either both or at least one of the participating organisms gets harmed.
- Parasitism and Competition are examples of negative interaction.
- In parasitism, one species benefits from growth and reproduction. They are usually referred to as a parasite growing at the expense of the other species i.e the host by harming them.
- In competition, two organisms compete for space, light, nutrients and suffer as their fitness reduces.