Basis of Classification

Unit 5

Basis of Classification

Learning Objectives

* To understand the need for dichotomous classification

* To classify animals according to their characteristic features

* To know the classification of animals and get the knowledge about invertebrates and vertebrates

* To acquire knowledge about the classification of plants

* To know the importance of five kingdom classification

* To understand the Binomial Nomenclature

Introduction

When you get ready to go to school, all your things - uniform, lunch box, water bottle, shoes etc., to be kept ready. Just imagine if all these things are not ready you will need to spend too much time to collect them. Likewise, in a grocery shop, medical shop and bakery all the items are systematically arranged. Sorting of things is very much required and important for all living beings. We see various plants and animals around us. It is estimated that about 8.7 million species of living organisms have been identified and named till now. However many scientists believe that, only a small portion of the total species existing on earth has been identified. In order to know about the behavior and relationship among organisms, that are known, biologists have classified them into two broad groups, plants and animals. Grouping of living organisms based on their common features is known as biological classification.

List out things found in your class room

Chair, Table, Black board, Chalk piece, Cupboard, Fan, Light, Switches, School bag, Lunch bag, Text book, Note book, Water bottle, Pencil box, Pencil, Pen, Rubber, Ruler, Door, Window, Writing pad, Colour pencil, Eraser, Sharpener, Compass, and Chart papers.

1. Find out one common difference among these materials to classify the above things into  two  Wooden / Non Wooden

2. Find out another difference to classify each group into two sub groups Wooden sitting materials / Wooden writing materials and Non wooden sitting material / Non wooden writing materials.

3. Continue to identify differences to classify each small subgroups into two Fixed / Portable, With arm / Without arm

There are some similarities and differences exist among these materials. So we need to observe and identify those similarities and differences to construct a dichotomous key.

The dichotomous key allows us to make quick reference and identify a particular thing. Classification provides scientists a systematic easy way of studying organisms. Classification is done using this dichotomous key. What is dichotomous key? It is a tool used to classify organisms based on their similarities and differences.

Features of dichotomous key

* A single feature that differentiate a group easily.

* One character selected to separate the group, as present or absent.

* Continue the 2nd step until only one item will remain at the end.

Dichotomy of Animals

Using a dichotomy pattern, classify the given list of animals: Ostrich, peacock, monkey, frog, toad, turtle, snake, shark, goldfish, ant, tapeworm, earthworm and leech.

1. Presence or absence of back bone, we can classify them into two groups.

2. Animals with back bone can be divided into its subgroup based on its body temperature.

3. Further classification can be done based on its difference like presence of feather or hair, scales etc.