Question

Phenetic classification of organisms is based on?
A. Dendrogram based on DNA characteristics.
B. Sexual characteristics.
C. Observable characteristics of existing organisms.
D. The ancestral lineage of existing organisms.

Answer 1

Hint: Phenetics and cladistics are two opposite components of evolutionary biology. Both the procedures however are used to find the relationships among species. Cladistics put the focus on the ancestral traits whereas phonetics does not.

Complete answer:
The phenetic classification came into being in the year 1763 and was first given by Michel Adanson. It is a type of classification which is based on the overall similarity of the organisms. Usually, morphology or other observable traits are used to classify the organisms. This type of classification does not consider genetic similarity and evolutionary relatedness.
It came in an era where advanced methods and technology were not available. In this type of classification groups were made based on a single or few observable characters (easily observed) for example turtles, lizards, crocodiles have been placed in the same class Reptilia based on being scaly tetrapods.
DNA (deoxyribonucleic acid) was not discovered till the 1860s so it is not possible to construct a dendrogram based on a molecule yet to be discovered and more importantly the basis of phenetic classification was observable characteristics.
So, Option (a) is incorrect.
Not only the sexual characters are focused on but overall characters are compared in phonetics.
So, Option (b) is incorrect.
The idea of lineage came later in the late 1780s. Therefore this is an incorrect option.
So, Option (d) is incorrect.

Hence, the correct answer is option (C).

Note: The classification used simple observable characters. The complex basis of classification cannot be used as many important molecules like DNA were not discovered and many concepts like lineage; evolution was yet to come into existence.