Biology m2

Module 2: Classification

  • Duration: 3 hours

  • Purpose: To emphasize that classification itself is not the core of biological studies; it is essential to highlight the underlying criteria used in classification.

Key Criteria for Classification

  • Morphological: Involves the study of the structure and form of organisms.

  • Biochemical: Focuses on the chemical processes and substances in organisms.

  • Ecological: Considers the interactions of organisms within their environments.

Hierarchy of Life Forms

  • A ranking system at a phenomenological level reflects a common thread of classification.

Classification Bases

  • Cellularity:

    • Unicellular: Organisms composed of a single cell.

    • Multicellular: Organisms made up of multiple cells.

  • Ultrastructure:

    • Prokaryotes: Organisms without a defined nucleus (e.g., bacteria).

    • Eukaryotes: Organisms with a defined nucleus (e.g., plants, animals).

  • Energy and Carbon Utilization:

    • Autotrophs: Organisms that produce their own food (e.g., plants using photosynthesis).

    • Heterotrophs: Organisms that consume others for energy.

    • Lithotropes: Organisms that obtain energy from inorganic compounds.

  • Ammonia Excretion Methods:

    • Aminotelic: Organisms that excrete ammonia directly.

    • Uricotelic: Organisms that excrete uric acid.

    • Ureotelic: Organisms that excrete urea.

  • Habitat:

    • Aquatic: Organisms that live in water environments.

    • Terrestrial: Organisms adapted to land.

  • Molecular Taxonomy:

    • Focuses on the genetic and molecular basis for classification, particularly the three major kingdoms of life.

Model Organisms in Biological Studies

  • Different groups provide important model organisms:

    • E. coli (bacteria)

    • S. cerevisiae (yeast)

    • D. melanogaster (fruit fly)

    • C. elegans (nematode)

    • A. thaliana (Arabidopsis plant)

    • M. musculus (house mouse)

  • Importance: Model organisms are crucial for studying biological processes and understanding various aspects of biology across different classifications.