Science - 2019-20

BIO.6 - Classification

The student will investigate and understand bases for modern classification systems. Key concepts include

a)  structural similarities among organisms;

b)  fossil record interpretation;

c)  comparison of developmental stages in different organisms;

d)  examination of biochemical similarities and differences among organisms; and

e)  systems of classification that are adaptable to new scientific discoveries.

Bloom's Levels:  Analyze; Understand

Adopted: 2010


  • Organisms are diverse, yet share similar characteristics.
  • Life can be organized into a functional and structural hierarchy.

  • I can identify how humans are similar to other organisms.
  • I can identify which dinosaurs were similar to one another.
  • I can identify how humans are similar to other organisms.
  • I can classify a newly discovered (or new to me) organism and relate it to other, similar organisms.


  • Biological classifications are based on how organisms are related. Organisms are classified into a hierarchy of groups and subgroups based on similarities that reflect their relationships over a period of time.
  • Binomial nomenclature is a standard way of identifying a species with a scientific two-word name. The first word is the genus name and the second the species name.Species is the basic unit of classification. A species is defined as a group of organisms that has the ability to interbreed and produce fertile offspring in nature.
  • A dichotomous key is a classification tool used to identify and organize organisms using defining characteristics.
  • Information about relationships among living organisms and those that inhabited Earth in the past is gained by comparing biochemistry and developmental stages of organisms and by examining and interpreting the fossil record. This information is continually being gathered and used to modify and clarify existing classification systems.
  • Evolutionary relationships can be represented using a branching diagram called a cladogram or phylogenetic tree which are organized by shared, derived characteristics.
  • Similarities among organisms on the structural and metabolic levels are reflected in the large degree of similarity in proteins and nucleic acids of different organisms. Diversity is the product of variations in these molecules.


In order to meet this standard, it is expected that students will

a)  describe relationships based on homologous structures.

     compare structural characteristics of an extinct organism, as evidenced by its fossil record, with present, familiar organisms.

c)  recognize similarities in embryonic stages in diverse organisms in the animal kingdom, from zygote through embryo and infer relationships.

d)  compare biochemical evidence (DNA sequences, amino acid sequences) and describe relationships.

b, e) construct and utilize dichotomous keys to classify groups of objects and organisms.

     interpret a cladogram or phylogenic tree showing evolutionary relationships among organisms.

     investigate flora and fauna in field investigations and apply classification systems.


evolution, theory, fossil, artificial selection, struggle for existence, fitness, adaptation, survival of the fittest, natural selection, descent with modification, common descent, homologous structure, vestigial organ

Updated: Dec 01, 2017