Name the layer of the atmosphere that is associated with ‘good ozone’.

OR

Mention the term used to describe a population interaction between an Orchid growing on a forest tree.

Stratosphere

Explanation:

Ozone gas is of two types: good ozone and bad ozone.
Bad ozone is formed in the lower atmosphere i.e. troposphere. It is harmful for plants and animals.
Good ozone is found in the upper atmosphere i.e. stratosphere. It protects from harmful ultraviolet rays from the sun.

OR

Commensalism

Explanation:
The interspecific interaction between Orchid and a forest tree is commensalism. Orchid grows as an epiphyte on the branch of a tree and benefits by having a habitat. In this situation, though the Orchid is benefited the tree is neither benefits nor is harmed. Such an interaction is called commensalism.