The interaction between an orchid and a mango tree represents which of the following?

Some plants have a habit of harbouring ants to save themselves from damage by other animals,which is known as:

Consider the following four statements and select the option which includes all the correct ones $:-$
$(a)$ Sparrow eating any seed is no less a predator.
$(b)$ Monarch butterfly is highly distasteful to its predator.
$(c)$ Nearly $25 \%$ of all insects are known to be phytophagous.
$(d)$ Thorns are the most common morphological defence mechanism.
Options $:-$

In which of the following can the best examples of mutualism be observed?

Define/Explain: Endoparasites.

What did Gause demonstrate regarding ecology and competition?