Some orchids grow high on trees so that they can get enough light for photosynthesis. the trees are unaffected by the presence of the orchids. the relationship between the orchids and the trees is an example of

Commensalism (Symbiotic relationship)

Explanation:

Commensalism is a type of symbiotic relationship in which one species gets benefits while the other species remain unaffected.

Orchids are epiphytes which grows  on  the inner branches of trees of rainforest that helps in taking nutrients directly from the air around them and sometimes from the decaying organic matter of their host tree. Epiphytic orchids  stores water in their stems  and compensate in dry periods. Trees having rough barks that holds humus and water in it's crack supports orchids better than other trees with smooth barks.

a tetrad is the foursome during meiosis made by two homologous chromosomes that have each already replicated into a pair of sister chromatids.

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light-years

magnitude