In ecology, mutualism can be described as a type of biological interaction in which two organisms of different species benefit from each other. We can say that the interaction among these organisms is positive.
In the above scenario, birds benefit the humans by guiding them to the directions for beehives. In return, the birds are able to feed on the hives and bees. Hence, this scenario is an example of mutualism.
We mean that..... only some substances are allowed to enter the cell. The membrane is responsible for the permeability of substances. Not all substances are permitted.