Page 91 - Biology_F5

Biology for Advanced Level Secondary Schools

under the same taxon have features unique Importance of taxonomic hierarchy in
to that group; thus, they can be used to classification
describe the entire group. For example, (a) It provides a standard method to be
members of same species have the largest followed by taxonomists in assigning
number of characters that are more similar scientific names to a newly discovered
and they can interbreed and produce fertile species. This makes it easy to classify
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offspring. Lions fall in the species Panthera or group organisms.
leo, leopard in Panthera pardus, and tiger
Panthera tigris. Thus, lion, leopard and (b) It provides a classification system of
tiger are different species in the same genus living organisms, which expresses
Panthera. The genus comprises relatively natural or evolutionary relationship
more closely related organisms with similar among the members of the same group
morphology, structure, reproductive organs and among various organisms.
and most importantly, evolutionary history (c) It provides smooth communication
compared to those at the higher ranks. among the taxonomists, while avoiding
However, they can not interbreed to produce confusion and repetition of the species
fertile offspring. A group of related species names.
forms a genus, and a group of related genera (d) It simplifies access to information on
forms a family. A group of related families various organisms across the taxa.
forms order, while a group of related orders
forms phylum or division and a group of
ralated phyla or divisions forms a kingdom. Exercises 2.1
Kingdom Plantae contains four divisions, 1. Explain the concept of “ranks” as
namely Angiospermophyta (Angiosperm), used in classification.
Coniferophyta (Gymnosperm), Pteridophyta
or Filicinophyta (Ferns and their relatives), 2. Explain what would be the problem
and Bryophyta (Moss). if organisms were not grouped into
categories or ranks.
Kingdom Animalia is composed of the 3. A form five student classified both a
following phyla: Porifera, Cnidaria, chicken and a grasshopper into the
Platyhelminthes, Nematoda, Annelida, same group based on observable
Arthropoda, Molusca, Echinodermata, features.
and Chordata. Organisms at the rank of
kingdom have a few features in common (a) Which system of classification
compared to the organisms at lower ranks. did the student use?
This book will focus on five selected (b) What are the demerits of the
phyla of Kingdom Animalia, which are system of classification the
Platyhelminthes, Nematoda, Annelida, student used?
Arthropoda, and Chordata.

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