An organism that obtains food and other requirements at the expense of another organism is called:

Describe competition.

Match the Column-$I$ and Column-$II$:

Column-$I$	Column-$II$
$(P)$ Lichens	$(i)$ Parasitism
$(Q)$ Abingdon tortoise and goat	$(ii)$ Commensalism
$(R)$ Sea anemone and clown fish	$(iii)$ Competition
$(S)$ Human and liver fluke	$(iv)$ Mutualism

The relationship between two organisms or species in which both partners derive benefit from each other is known as:

Which adaptations have parasites evolved to exhibit parasitism?

Given below are two statements:
Statement $I$: Gause's competitive exclusion principle states that two closely related species competing for different resources cannot exist indefinitely.
Statement $II$: According to Gause's principle,during competition,the inferior will be eliminated. This may be true if resources are limiting.
In the light of the above statements,choose the correct answer from the options given below :