Which of the following statements is NOT true of symbiosis?

Explanation

Symbiosis is a close association between two different organisms that live together. The question is asking which statement is not true of symbiosis. Option A states that symbionts must be living, and this is true because symbiosis involves living organisms. Option B states that symbiosis is an association of 'give and take', and this is also true because both organisms in a symbiotic relationship benefit from each other. Option C states that the association may involve two plants, and this is also true because symbiotic relationships can occur between any two organisms, including plants. Option D, which is the correct answer, states that the association is between two similar species. This statement is not true because symbiotic relationships can occur between different species, not just similar ones. It is important to note that symbiosis can be beneficial, harmful, or neutral to both organisms involved. Examples of symbiotic relationships include mutualism, commensalism, and parasitism. Mutualism is a type of symbiotic relationship where both organisms benefit from each other, commensalism is where one organism benefits while the other is neither helped nor harmed, and parasitism is where one organism benefits at the expense of the other. In summary, the correct answer to this question is option D, which states that symbiosis occurs only between two similar species, which is not true. Symbiotic relationships can occur between different species and can be beneficial, harmful or neutral to both organisms involved.