Biological classification is a dynamic and ever evolving phenomenon which keeps changing with our understanding of life forms .Justify the statements taking two examples.

Hint Linnaeus classified the living world into two kingdoms. Plantae and animalia. As the biological classification is always changing so further R.H whittaker proposed five kingdom classification for more clarification of organisms.

Complete answer: To answer this question you must know about biological classification.
Biological classification of organisms was first done by Aristotle. He classified plants to trees ,herbs ,shrubs and animals into two groups: red blood and without red blood. And it was proposed by Linnaeus in 1758 who further classified it into two kingdoms: plantae and animalia.
Further To solve this problem the organisms are classified into five kingdoms by Robert hook whittaker in 1969.it include monera, protista, fungi, plantae, and animalia based upon cell structure, organization, mode of nutrition, reproduction and phylogenetic relationships.
Earlier classification systems include bacteria, blue green algae, fungi, mosses, ferns, gymnosperms and angiosperms under plants. In which all organisms are mixed such as prokaryotes, eukaryotes, unicellular, multicellular etc. so after knowing all the other characteristics we separate these organisms into different kingdoms. This change occurs because the criteria of classification is changed .
This kind of changes will take place in the future depending upon improvement and our understanding of other characteristics as well as evolutionary relationships, so that’s how we can say biological classification is a dynamic and ever evolving phenomenon which keeps changing with our understanding of life forms.

Note:- Biological classification is also known as taxonomy in which biologists group organisms based upon their characteristics. Science has evolved over time such as since early 20th century grouping is supposed to fit the Darwinian principle and these days, molecular evolution studies, this often called as phylogenetics.